June 16, 2025

How do you make a snapshot backup?

How do you make a snapshot backup?

This episode breaks down snapshot backup fundamentals, covering the key differences between traditional storage snapshots and cloud-based approaches. Curtis and Prasanna explain copy-on-write versus redirect-on-write methods, performance implications, and why some snapshot systems can degrade performance by up to 50%.

Learn about NetApp's redirect-on-write innovation, VMware's unique approach, and how AWS "snapshots" are actually more like traditional backups. The hosts discuss critical concepts like read-only snapshot properties, storage space management, and the importance of copying snapshots to create true backups that follow the 3-2-1 rule.

Whether you're managing traditional storage arrays or cloud infrastructure, this episode provides practical guidance on turning snapshots into effective backup strategies. Topics include performance optimization, immutable storage considerations, and real-world implementation challenges that every IT professional faces.

Speaker:

You found the backup wrap up your go-to podcast for all things

Speaker:

backup recovery and cyber recovery.

Speaker:

In this episode, we tackle a confusing phrase, snapshot backup.

Speaker:

I know what you're thinking, Curtis.

Speaker:

Isn't that an oxymoron?

Speaker:

Well, that depends on what you mean by snapshot.

Speaker:

We're gonna break down the difference between what I'm calling

Speaker:

traditional storage snapshots and what vendors like AWS call snapshots.

Speaker:

Which are actually more like backups.

Speaker:

We'll talk about copy on write?

Speaker:

Redirect on write.

Speaker:

VMware snapshots that are just weird.

Speaker:

How to turn your snapshots into actual backups that follow the 3, 2, 1 rule.

Speaker:

Uh, pretty much everything that you need to know about making.

Speaker:

A backup snapshot.

Speaker:

If you don't know who I am, I'm w Curtis Preston, AKA, Mr.

Speaker:

Backup, and I've been dealing with this topic for over 30 years, ever since.

Speaker:

I had to tell my boss that there were no backups of the production

Speaker:

database that we had just lost.

Speaker:

I don't want that to happen to me.

Speaker:

I don't want that to happen to you.

Speaker:

That's why I do this.

Speaker:

And so, enjoy this episode of the backup wrap up.

Speaker:

Welcome to the show.

Speaker:

Hi, I am w Curtis Preston, AKA, Mr. Backup, and I have with me my QOS advisor

Speaker:

Prasanna Malaiyandi how's it going?

Speaker:

Prasanna?

Speaker:

I am good Curtis, and I'm glad that we don't have a random five second lag

Speaker:

every time we talk, so That's good.

Speaker:

Yeah.

Speaker:

So, uh, we figured out, we, we were, we started to try to record this

Speaker:

and there was this massive lag.

Speaker:

Um, and, um, I realized that basically like I counted 'em real quick.

Speaker:

There are four people currently watching Netflix.

Speaker:

Uh, I was able to stop one of them, but I don't control the other ones.

Speaker:

And so you came up with the idea of, you know, what about QOS?

Speaker:

And so I, I have a firewall.

Speaker:

Um, and, uh, so I, I enabled SmartQ, I put this website on it and I

Speaker:

said, give me, gimme all the stuff.

Speaker:

Gimme everything I can.

Speaker:

And uh, so now it's, you know, beautiful.

Speaker:

So I guess that's a plug for firewall as well, not a sponsor.

Speaker:

Yep.

Speaker:

Or for any router software that actually supports proper QOS, not like most

Speaker:

Yeah.

Speaker:

consumer level ones, which don't do a great job.

Speaker:

Yeah, so this is, I I've been very happy with the, with

Speaker:

the firewall since I got it.

Speaker:

Uh, every once in a while I use something, you know, fancy on it when this is nice.

Speaker:

So, um, so, um, we haven't recorded in a while.

Speaker:

You, you went away.

Speaker:

I went away.

Speaker:

I went on vacation for the longest vacation I've been

Speaker:

on in seven years I think.

Speaker:

So I was gone out of the country for three weeks, which was nice.

Speaker:

I was off in India for a wedding, visiting family.

Speaker:

Lots of travel.

Speaker:

So much good food.

Speaker:

Curtis, um, and

Speaker:

Yeah.

Speaker:

I might be addicted to caffeine.

Speaker:

So

Speaker:

In India as you've had, right, uh, they serve in the south, they

Speaker:

serve filter coffee, which is sort of a small cup of coffee, which

Speaker:

is very, very concentrated though.

Speaker:

And, uh, I was drinking three or four a day.

Speaker:

Now this is normally someone who drinks maybe one cup of

Speaker:

coffee a day, other than when

Speaker:

Yeah.

Speaker:

office where it's maybe two.

Speaker:

So.

Speaker:

Yeah.

Speaker:

Yeah.

Speaker:

Well anyway, well welcome back to the same time zone.

Speaker:

Very excited.

Speaker:

Thank you.

Speaker:

but It is hard with the 12 and a half hour time zone difference.

Speaker:

You know, it was like

Speaker:

Yeah,

Speaker:

we get a brief window to chit chat, or in the evenings we get a brief window to chit

Speaker:

yeah, yeah.

Speaker:

I basically wake up and call you and then before I go to bed, I call you.

Speaker:

Right.

Speaker:

Um, and, um, uh, yeah, so a lot of people don't know that it's,

Speaker:

that it's 12 and a half hours time difference, which is just odd.

Speaker:

yeah, I don't know why they do the half hour.

Speaker:

Yeah, just funny.

Speaker:

Maybe they, they saved the half hour to drink the filter coffee.

Speaker:

So, uh, all right, well, today we're gonna talk about, uh, you know, and I

Speaker:

thought, you know, you thought maybe we'd covered this already, or at least

Speaker:

recently, and, and we really haven't.

Speaker:

So this is a, a word that comes up a lot in, uh, in the show.

Speaker:

And that is this word snapshot, which.

Speaker:

If, if we, if we go outside of it, it, it, it means that, you

Speaker:

know, it's, it's a picture, right?

Speaker:

That that's what the word snapshot and also.

Speaker:

There's another word that's gonna be used in this episode, which is image, which

Speaker:

is really just another word for picture.

Speaker:

But in our world, an image is very different than a snapshot.

Speaker:

And as you've often heard me say, words mean things.

Speaker:

And um, I want to make sure that this is sort of a, I'm gonna

Speaker:

call it snapshots basic episode.

Speaker:

So if you're, if you're just wondering what you know, what are snapshots, what

Speaker:

are the different types of snapshots?

Speaker:

Both what I'm gonna call the traditional snapshot, which is the ones that you and

Speaker:

I, you know, grew up on, if you will, and then something that is relatively new.

Speaker:

Again, comparatively speaking, new, uh, that is also being called

Speaker:

snapshots, which is actually something completely different.

Speaker:

So, um, uh, and then what purpose they serve, uh, et

Speaker:

cetera, et cetera, et cetera.

Speaker:

Any, any other sort of introductory things you can think of before we get started?

Speaker:

no.

Speaker:

I also did like your analogy of a snapshot is like a picture

Speaker:

that you would take right

Speaker:

Yeah.

Speaker:

of like tech, right?

Speaker:

And,

Speaker:

Yeah.

Speaker:

thing to add is that's important is it captures a moment in time.

Speaker:

Yes.

Speaker:

Right.

Speaker:

A

Speaker:

One moment in time.

Speaker:

Sorry,

Speaker:

and

Speaker:

go ahead.

Speaker:

but, so we're not referring to a video or whatever Apple calls

Speaker:

their eight second or six second

Speaker:

Yeah,

Speaker:

that they send over.

Speaker:

Right.

Speaker:

That's not what we're referring to.

Speaker:

It's a single

Speaker:

Yeah.

Speaker:

Yeah.

Speaker:

So first let's talk about what I'm gonna call the traditional snapshot

Speaker:

and, um, which I, another word, it's funny now that I think about it.

Speaker:

This other word that I'm gonna use is also sort of like, um, it's

Speaker:

also a word that is used outside.

Speaker:

Id to also mean.

Speaker:

You know, looking at a thing, right?

Speaker:

And, uh, the word that I'm gonna use is view.

Speaker:

Mm-hmm.

Speaker:

So, uh, if anybody has any experience in databases.

Speaker:

Right.

Speaker:

There is this concept called a view, which is a different view into the database,

Speaker:

which gives you, it looks different than, um, than the, the, the entire database.

Speaker:

Right.

Speaker:

It is a, it is a view, a a particular point of view, if

Speaker:

you will, into the database.

Speaker:

I don't want to go too much into that for two reasons.

Speaker:

One is not really relevant.

Speaker:

Two, I will probably mess up the description, but, um.

Speaker:

Because it's one of those areas where it's right at the edge of my, of my experience.

Speaker:

I am not a DBA, um, but I've often had to pretend to be one

Speaker:

in order to back up databases.

Speaker:

But this goes to your concept or your, the, the point that you were

Speaker:

making is that a snapshot, uh, is a view of the storage at a particular

Speaker:

point in time, so it is a view of your typically file system, but also

Speaker:

it could just be a volume, right?

Speaker:

A virtual volume at a particular point in time and what your, when

Speaker:

you look at that snapshot, the actual blocks that you are looking at, or

Speaker:

you're copying or you're accessing.

Speaker:

What you are looking at.

Speaker:

Is going to like where the blocks come from is going to be based on how the

Speaker:

snapshot is actually being delivered.

Speaker:

Sometimes you are going to be looking at the blocks from

Speaker:

the original storage device.

Speaker:

Sometimes you're going to be looking at blocks from some

Speaker:

sort of cash snapshot area.

Speaker:

Mm-hmm.

Speaker:

Um, and so this view that you're looking at is this sort of virtual

Speaker:

view of a particular point in time and it just keeps track of everything.

Speaker:

And it says, okay, at this point in time they go to ask for this block.

Speaker:

It knows what was where.

Speaker:

So it goes, at this point in time, block A was.

Speaker:

You know, at this status, well block A is still that status over on the original

Speaker:

storage device, so we're gonna go get it.

Speaker:

Or if you ask for block B, you go, block B was this status, and we can

Speaker:

see that that status has changed.

Speaker:

And so we're gonna get that block from the snapshot area.

Speaker:

Um,

Speaker:

And

Speaker:

go ahead.

Speaker:

does a different implementation.

Speaker:

Yeah.

Speaker:

think most of.

Speaker:

As of what I know right now is they're all kind of, all the blocks

Speaker:

are shared, and like you said, as things change, new copies are created

Speaker:

that contain the updated version.

Speaker:

But there's all this metadata and mapping, all this stuff is what

Speaker:

the storage vendors, that's really like what they focus on, right?

Speaker:

Is how do they make it fast?

Speaker:

How do they make sure that you have that plausible point in time view to look at.

Speaker:

Yeah.

Speaker:

And, uh, we're gonna talk about, uh, like a couple of different

Speaker:

ways that this actually happens.

Speaker:

Uh, but the, but when you think about the way I described how that works,

Speaker:

the important thing to understand is I said that if you grab blocks, one

Speaker:

part of the, you know, one set of blocks where you're going to get those

Speaker:

blocks from is from the original.

Speaker:

Thing, right?

Speaker:

The, the device, the volume, et cetera.

Speaker:

And the other way is you're gonna get blocks from the snapshot area, but

Speaker:

the, but the thing that you should infer from that is that in order for

Speaker:

the snapshot to function, you need the original device to continue to be

Speaker:

Mm-hmm.

Speaker:

functional and et cetera, et cetera, et cetera.

Speaker:

Yeah.

Speaker:

Yeah.

Speaker:

Um,

Speaker:

thing to

Speaker:

yeah.

Speaker:

that's important for snapshots Curtis

Speaker:

Mm-hmm.

Speaker:

is that snapshots are read only, right?

Speaker:

Which is a critical fundamental, uh, the, the property of a snapshot, right?

Speaker:

Just like a

Speaker:

Yes.

Speaker:

you take a picture, you're not modifying that picture,

Speaker:

Right.

Speaker:

Good point, good point.

Speaker:

Um, and because otherwise it wouldn't be a snapshot of that point in time.

Speaker:

Now you can take a snapshot and you can make it read, right?

Speaker:

But at that point, it's really no longer a snapshot, right?

Speaker:

Um, it is a completely different sort of function.

Speaker:

Yeah, and typically for those ones do have that snapshot, and then

Speaker:

normally when you make it read, write, you're creating a new entity.

Speaker:

So the snapshot still exists, but then the all the writes go

Speaker:

Correct,

Speaker:

entity.

Speaker:

correct.

Speaker:

Correct.

Speaker:

Um, so there are.

Speaker:

Two different ways that snapshots, again, traditional snapshots are typically done.

Speaker:

And there's what I'm gonna call, um, sort of the the traditional Traditional, okay.

Speaker:

And that is this concept.

Speaker:

And this is pre NetApp, basically right before NetApp started doing snapshots.

Speaker:

'cause NetApp really kind of reinvented snapshots and, and how they work, right?

Speaker:

Before NetApp, you had what was called the copy on write Snapshot and where

Speaker:

it gets, or CCOW copy on write Snapshot and where it gets that, that name is

Speaker:

that you, you have a block, right?

Speaker:

When, when you make the snapshot at the very beginning of making the snapshot,

Speaker:

all blocks are in the original device.

Speaker:

Because nothing has changed.

Speaker:

The moment you go to do something, you go to update, you know, a block.

Speaker:

The question is what happens now?

Speaker:

So in a copy on write situation, the um.

Speaker:

We're going to, before we change that block, we're going to copy that block out

Speaker:

to the snapshot area so that later when we go to, um, access that block, we say, oh,

Speaker:

we need the block from this point in time.

Speaker:

That block, at that point in time, is only available over

Speaker:

in the snapshot area, right.

Speaker:

What's important to understand is that when you go to update a, a block

Speaker:

with a copy on write, um, snapshot, it has to do a right of that block.

Speaker:

It has to move the data, then copy, you know, write that.

Speaker:

Old block in the snapshot area, and then it's gonna write the

Speaker:

new version of that block.

Speaker:

So there are three IO operations for every right operation

Speaker:

in a copy on write snapshot.

Speaker:

And then the more snapshots you have.

Speaker:

And the more, and the longer you keep them, the more, uh, of your blocks

Speaker:

that you're going to have to copy every time you, uh, write new data.

Speaker:

Is that, how did I do with that explanation?

Speaker:

yeah, you did.

Speaker:

Well, um, the other thing also is at some point you end up with a

Speaker:

Yeah.

Speaker:

As well, just because of how writes are being done.

Speaker:

And remember all the time, these aren't just small blocks, right?

Speaker:

So even if you go modify, say a hundred bytes in a block, you still

Speaker:

have to write that entire block back,

Speaker:

Yeah.

Speaker:

Yeah.

Speaker:

sort of the underlying building block for the file system.

Speaker:

And

Speaker:

Right.

Speaker:

this could lead to a lot of wasted reads and writes and IO that you're consuming.

Speaker:

Are you, did you just say that the block is the basic building block?

Speaker:

It is funny, the words that we use, right?

Speaker:

Um, yeah.

Speaker:

And so, um, what's it, I, I think one of the most important things to understand

Speaker:

about a copy on write Snapshot set up is that over time, if you have a lot of

Speaker:

snapshots and you keep those snapshots for a significant amount of time.

Speaker:

The performance of your primary array because it's having to do all of this

Speaker:

copying, you know, on, you know, on write.

Speaker:

The performance of that, both the read performance and the, and

Speaker:

especially the write performance can be significantly degraded over time.

Speaker:

Yeah, and I'm just thinking, don't know any systems to my

Speaker:

Mm-hmm.

Speaker:

that still use copy on write.

Speaker:

I am sure there are some, but I, but I would agree with you that

Speaker:

most newer storage vendors realize sort of the evil of copy on write.

Speaker:

You know, the, the, you know, it's, it's, I. It's, it's, it's sort of like

Speaker:

the famous Maya Angelou quote, right?

Speaker:

Like, we did what we did when we knew what we knew, but now we know

Speaker:

different and we do different.

Speaker:

Right?

Speaker:

Uh, that's a, that's a massive, uh, I'm sure misquote of, but I think I

Speaker:

got, I think I got the concept there.

Speaker:

And I remember being at a large, very large oil and gas company

Speaker:

and we were, um, you know.

Speaker:

Helping them do a, it was an, it was a RFP, right?

Speaker:

Um, for, for just a massive, uh, storage change.

Speaker:

Right.

Speaker:

And, um, they knew how many snapshots they wanted to create, and they knew

Speaker:

how long they wanted to create them.

Speaker:

They were already a, a NetApp customer.

Speaker:

The, the problem with being a NetApp customer was they knew every.

Speaker:

Bad thing about NetApp, right?

Speaker:

They, they, they could see right through the stuff that they said that was bs.

Speaker:

Right.

Speaker:

You know, every vendor has got some amount of bs, but they were a customer,

Speaker:

so they knew everything that NetApp, you know, they knew every blemish about

Speaker:

NetApp, but they, and they were bringing in other vendors to see if perhaps they

Speaker:

could get what they get from NetApp.

Speaker:

Uh, while changing the vendor.

Speaker:

And one of the things that they want is they wanted 90 days of user

Speaker:

browsable snapshots, and they had all this data to show how much money

Speaker:

that that was saving them because of the number of user generated

Speaker:

restorers that were happening, right?

Speaker:

Because one of the great things about having snapshots is that if you give

Speaker:

them access, your users can just go to the right area and they can see their

Speaker:

directory from a different point in time.

Speaker:

Right?

Speaker:

And so they, they had all this data that showed that they had all these user.

Speaker:

Generated restores and um, uh, and so they said we want 90 days

Speaker:

of user browsable snapshots.

Speaker:

I won't name the vendor, but let's just say it's a fundamental law of physics.

Speaker:

Um.

Speaker:

That vendor said, uh, if you do that, you know, you're, you're, you're, 'cause

Speaker:

they were, you know, they were doing copy on write snapshots at the time, and

Speaker:

they basically said, you're going to have a significant performance degradation.

Speaker:

And they, and they asked them like, how bad, and they just sort of, you know.

Speaker:

Spitball the number, and they said it was 50%, like a 50% performance

Speaker:

degradation, but they're like, we actually don't know because no one does

Speaker:

that, no one does that with our storage.

Speaker:

Right.

Speaker:

Um, and, um, uh, yeah, so it's, it's a really big deal.

Speaker:

Right.

Speaker:

So that is,

Speaker:

Yeah.

Speaker:

I. Copy on.

Speaker:

Right?

Speaker:

Which is the old school way of doing snapshots.

Speaker:

And if you're currently having any problems with your snapshots,

Speaker:

maybe you investigate and see if they're copy on write?

Speaker:

That's gonna be your core problem, right?

Speaker:

Um, and, and it's gonna fall under the category of

Speaker:

doctorate hurts when I do this.

Speaker:

Well, don't do that.

Speaker:

You need to do fewer snapshots or whatever.

Speaker:

I just realized there is one vendor that still does copy on.

Speaker:

write.

Speaker:

And do you know what that is?

Speaker:

Who?

Speaker:

Microsoft with VSS Snapshots?

Speaker:

VSS.

Speaker:

The volume shadow services.

Speaker:

Yeah.

Speaker:

Yeah.

Speaker:

Yeah.

Speaker:

I was just thinking about that.

Speaker:

I'm like, there has to be someone, and I was like, oh, yep.

Speaker:

Yeah.

Speaker:

And, and by the way, that brings up a, a really good, uh, thing that maybe

Speaker:

we should have covered earlier on.

Speaker:

And why do you, why do you make snapshots?

Speaker:

Right?

Speaker:

There's two reasons.

Speaker:

And VSS is the second reason.

Speaker:

The first reason is that it acts as sort of, kind of like a backup

Speaker:

Mm-hmm.

Speaker:

that it gives you this view, this place that you can go get and get the file

Speaker:

the way it looked three weeks ago, three months ago, six months ago, whatever.

Speaker:

However long you keep your snapshot.

Speaker:

Go ahead.

Speaker:

can we call it little B backup?

Speaker:

Because, because here, here's my

Speaker:

I what you're saying?

Speaker:

Yeah.

Speaker:

gets, because it doesn't follow the traditional

Speaker:

Yeah.

Speaker:

backup of 3, 2, 1 rule and everything

Speaker:

Yeah, that's why I'm saying it's kind of like a backup, right?

Speaker:

Yeah.

Speaker:

Um, it, it's not really a backup until you copy that snapshot

Speaker:

to some other location, right?

Speaker:

So, and it also needs to be managed and all that kind of stuff,

Speaker:

and you need to know what's in it and all that kind of thing.

Speaker:

Anyway, but to, to follow the 3, 2, 1 rule, you need to at least

Speaker:

copy it to another location.

Speaker:

Hopefully that location is offsite and now we got three

Speaker:

copies and two locations we got.

Speaker:

Okay.

Speaker:

So, um, actually, if all you're doing is.

Speaker:

Snapshot of replication, you're actually not following 3, 2, 1 either because

Speaker:

it's not, you don't follow the two, you don't have, you know, 'cause the two is

Speaker:

meant to be two different risk profiles.

Speaker:

And if you, if you go from one filer to another filer and you're, yeah.

Speaker:

Okay.

Speaker:

Um.

Speaker:

The second reason that you make a snapshot and VSS falls under this

Speaker:

typically, and that is what you're doing, is you're creating a stable

Speaker:

point in time that is now read only that you can then use to back up.

Speaker:

Mm-hmm.

Speaker:

You can point your backup.

Speaker:

And most backup vendors that are, that support windows, they integrate with VSS.

Speaker:

And what VSS do?

Speaker:

You, you, you talk to VSS and, , basically, you know, quick

Speaker:

summary there, there's, there's this concept of a, of a VSS writer.

Speaker:

You talk to the VSS and you say, Hey, I'm here to do a backup.

Speaker:

What kind of, um, you know, what kind of stuff do you have?

Speaker:

And they're like, we have SQL Server.

Speaker:

You're like, okay, do a snapshot for SQL Server, and then you, and then

Speaker:

that gives you a, a stable point in time to back up this, this device that

Speaker:

otherwise is moving around, right?

Speaker:

So it, it gives you a read.

Speaker:

Only copy that isn't changing while you're backing it up.

Speaker:

And then if you're just there to do a backup, it actually immediately

Speaker:

deletes the snapshot as soon as you're done with the backup.

Speaker:

Right.

Speaker:

So that's the second reason that we use a, a snapshot, which is

Speaker:

just to create a stable point in time from which we're gonna run.

Speaker:

I'll call it a big B backup to use your, to use your, your terminology.

Speaker:

All right.

Speaker:

So that's copy on write?

Speaker:

Uh, do you wanna describe, redirect on write.

Speaker:

Yeah.

Speaker:

So this is basically what NetApp does

Speaker:

Yeah.

Speaker:

Although they would say no 'cause they say there's a slightly

Speaker:

different, but that's okay.

Speaker:

You know?

Speaker:

Yeah.

Speaker:

NetApp is probably most famous for this with its write anywhere file layout

Speaker:

Yeah.

Speaker:

right?

Speaker:

Which basically says when you're going to actually do your writes, you don't

Speaker:

need to overwrite the existing block.

Speaker:

Right.

Speaker:

gonna pick any other random block, and then you're just

Speaker:

gonna keep track of where it is.

Speaker:

So all new writes go to all new blocks, so you don't have to ever

Speaker:

worry about going and updating all the metadata and copying data out, and so

Speaker:

you're efficient in your write code.

Speaker:

Pap and managing snapshots becomes a lot easier.

Speaker:

And so the where the term redirect on write, is instead of overriding the

Speaker:

block in its current location, you're just gonna redirect that, write?

Speaker:

Put it in another location, and then your snapshot manager just needs to keep

Speaker:

track of where the old location was.

Speaker:

So the big difference between a redirect on write, so there's a,

Speaker:

there's a plus and minus here.

Speaker:

The plus is much better performance,

Speaker:

Yep.

Speaker:

right?

Speaker:

Which is why.

Speaker:

Pretty much most vendors have gone with that as the newer.

Speaker:

Um, the downside is snapshot data and production data all

Speaker:

in the same volume, right?

Speaker:

There's no snapshot area.

Speaker:

It's, it's everything.

Speaker:

So if you keep snapshots too long, you can actually fill up your, your

Speaker:

volume, um, and have a problem.

Speaker:

Yeah.

Speaker:

And they, that's why they do try to do things like setting up a

Speaker:

snapshot reserve space so you can automatically start deleting it

Speaker:

once it gets to certain too high.

Speaker:

But yeah, there are cases where that could also still be problematic.

Speaker:

So,

Speaker:

Yeah.

Speaker:

And, and this is why, because you can do snapshots essentially.

Speaker:

With impunity, you can do as many snapshots as you want, as often

Speaker:

as you want, without, um, and, and keeping them as long as you

Speaker:

want without any zero performance.

Speaker:

Issues as long as you keep enough storage around for your snapshots, right?

Speaker:

Uh, 'cause then we start getting low on blocks and we start, you know,

Speaker:

then we, that, that, that, that, that's a totally different problem.

Speaker:

So as long as you have enough space for your, uh, for everything,

Speaker:

then you shouldn't have any performance from redirect on write?

Speaker:

Snapshots.

Speaker:

Yep.

Speaker:

And I think with it now, I think the latest NetApp snapshot limit

Speaker:

is I think a thousand snapshots.

Speaker:

It used to be 2 55 for a while, but

Speaker:

Yeah, the,

Speaker:

a

Speaker:

the famous 2 55 and yeah.

Speaker:

Yep.

Speaker:

It's funny how that number just sort of, well, 2 56 really is the number,

Speaker:

but 2 55 is, we can't do 2 56.

Speaker:

We can do two.

Speaker:

Well, it's 2 55 because active is always zero.

Speaker:

Oh, there you go.

Speaker:

There you go.

Speaker:

Yeah.

Speaker:

Yeah.

Speaker:

Um, so that's redirect on write.

Speaker:

And that, you know, and we, we really talked about it very quickly, but

Speaker:

basically it means that you can have as many snapshots as you want, as long as you

Speaker:

want without any performance degradation.

Speaker:

So that's generally what you find in most common, uh, snapshot providers right now.

Speaker:

other thing I wanna also mention, copy on write?

Speaker:

Versus redirect on write.

Speaker:

Mm-hmm.

Speaker:

discs, it made a huge benefit For Flash.

Speaker:

It makes an even bigger impact with Flash there are issues around

Speaker:

right amplifications when you're

Speaker:

Mm-hmm.

Speaker:

um, as well as how many wear cycles you can have on your flash.

Speaker:

And so redirect on write is actually much better, both from a performance

Speaker:

and longevity perspective for Flash

Speaker:

Right.

Speaker:

was on disc.

Speaker:

So

Speaker:

So the prob the problem there is that you're worried that you're having

Speaker:

too many writes to one cell, and each individual cell in, um, flash has.

Speaker:

A limited number of times that it can be overwritten, right?

Speaker:

And so the worry that you have is if you have too many writes to the same block,

Speaker:

you actually end, uh, to the same cell.

Speaker:

You actually end up, that cell can become, uh, no longer usable

Speaker:

but basically each cell has a finite number of times that you

Speaker:

can overwrite that cell and you hit that and that cell is done.

Speaker:

And now you know, it's like a bad block on a, or a bad sector on a disc, and

Speaker:

you gotta move on to the next sector.

Speaker:

and, and one other thing to mention too is I know so far when we talk about

Speaker:

writes, people are probably thinking, oh, you're just writing a block of data.

Speaker:

But remember with that block, you have a bunch of metadata

Speaker:

associated with it, right?

Speaker:

Indirect blocks that point to other blocks that contain metadata and everything else.

Speaker:

That all needs to be updated by a file system.

Speaker:

So even just doing like a hundred byte right,

Speaker:

Mm-hmm.

Speaker:

require, say.

Speaker:

20 other blocks to be updated as

Speaker:

Right, right.

Speaker:

Exactly.

Speaker:

Yeah.

Speaker:

So those, so those are the two sort of what I'd call traditional snapshots.

Speaker:

Right.

Speaker:

Um, and now, and the second one is now what I would call

Speaker:

sort of the standard snapshot.

Speaker:

yeah.

Speaker:

is a third.

Speaker:

Really weird way that his snapshots are done, which I'm

Speaker:

just gonna cover really quick.

Speaker:

And that is VMware.

Speaker:

So they do a, um, I, I believe it's a copy on write, but what's real

Speaker:

actually, actually they do a, I'm gonna call it a weird on write?

Speaker:

So what they do when you write a new block.

Speaker:

They don't write the block to the, and and by the way, this is my understanding

Speaker:

of the way VMware's, um, snapshots work.

Speaker:

If I am now wrong, please tell me, but this is, I've checked repeatedly and this.

Speaker:

I believe is still the case.

Speaker:

So what would happen is when you take a snapshot in VMware, usually for backup

Speaker:

purposes, um, when you go to write a new block in VMware, it doesn't write

Speaker:

the new block in the production area.

Speaker:

It writes the new block over in the snapshot area, leaves the

Speaker:

original version of the block on the disc, and then it stays that way.

Speaker:

Until you delete the snapshot, in which case it updates all the blocks to the new,

Speaker:

Yep.

Speaker:

thing.

Speaker:

And, and, which is why, and, and I, I administered VMware for, for

Speaker:

a while at least not really in a production environment, but, but

Speaker:

you know, in a lab for a while before I realized this was the case.

Speaker:

And so it means, what that really means in practice is you really can't use.

Speaker:

At all.

Speaker:

You can't use VMware snapshots the way you can use NetApp snapshots

Speaker:

or even copy on write snapshots because the performance is way worse.

Speaker:

Right.

Speaker:

Uh, at some point you go to delete snapshots and you think deleting

Speaker:

snapshots would be a nice thing, except when you delete the snapshot, there's

Speaker:

this flurry of IO activity to update the primary volume with any of those blocks

Speaker:

that are now the, the current block.

Speaker:

It's the messiest thing I've ever seen.

Speaker:

So two things to add.

Speaker:

One is for VMware, it's okay if you keep those snapshots around.

Speaker:

For a short duration.

Speaker:

For a short duration.

Speaker:

Yeah.

Speaker:

for a short

Speaker:

Yeah.

Speaker:

it's fine, but don't think about using it for like that 90 day user restore use

Speaker:

Mm-hmm.

Speaker:

that you were mentioning earlier,

Speaker:

it for a day or so.

Speaker:

Right.

Speaker:

And then delete it.

Speaker:

Right.

Speaker:

Make that a normal part of your thing.

Speaker:

Exactly.

Speaker:

And then the second point is with all of these snapshots, VSS VMware, most

Speaker:

of them support two modes of operation.

Speaker:

One is sort of a software based snapshot approach where they're

Speaker:

dealing with all of this.

Speaker:

So like Curtis mentioned with VMware, right?

Speaker:

They're keeping track of everything.

Speaker:

The second thing, second way that they also support it, is they

Speaker:

integrate with the storage vendors.

Speaker:

So when you go say VMware, go take a snapshot.

Speaker:

VMware will do some things and then it'll call into the underlying storage

Speaker:

provider and say, okay, now go do a hardware snapshot and lock in that data.

Speaker:

In which case then you don't have all of these issues that Curtis just

Speaker:

Exactly.

Speaker:

That's a really good point.

Speaker:

Thanks for, uh, bringing that up.

Speaker:

Right.

Speaker:

So VSS and VMware and maybe other sort of software level snapshots, they

Speaker:

do have this concept of talking to a storage array and then putting that

Speaker:

storage array, making, making, letting the storage array do the hard work.

Speaker:

Right.

Speaker:

Which is, which is.

Speaker:

I, I think certainly the preferred way to do snapshots is to do it in, in hardware.

Speaker:

Yeah.

Speaker:

. So the final way of snapshots, and this is the snapshots that most of you

Speaker:

know, because most of you are very, you are your head's in the clouds, right?

Speaker:

And that is, and, and I'm, I blame Jeff Bezos, um, because it

Speaker:

was Amazon, I believe that first started using the term snapshot.

Speaker:

To actually refer to something completely different.

Speaker:

If you go into a, you know, if you go to a number, it used to just be

Speaker:

like EBS, the Elastic Block storage.

Speaker:

Right.

Speaker:

Um, that, or you take, uh, a snapshot of a EC2 E image.

Speaker:

Yeah.

Speaker:

RDS Right.

Speaker:

You know.

Speaker:

If you take a snapshot, as I made quotes in the air, it doesn't do

Speaker:

anything like what we just said.

Speaker:

It creates what I would call an image copy, right?

Speaker:

Of that thing that you just took a snapshot of and it creates a

Speaker:

basically bite for bite copy of that.

Speaker:

And typically, I think it's, I'll just speak in terms of a, you know, AWS,

Speaker:

it creates that bite for bite copy in.

Speaker:

S3, right?

Speaker:

It stores it in a special reserve area in S3, and so when you create a snapshot

Speaker:

in pretty much anything in Amazon, what you're actually creating is a backup.

Speaker:

You're creating an image copy of that device.

Speaker:

You're putting it in S3.

Speaker:

Um, you can even, um, you can often specify where an S3, right, so you

Speaker:

can specify that you want that backup to go to another region, for example.

Speaker:

Um, and you can also copy these snapshots around, um, and, um, yeah,

Speaker:

But you can't access it directly via S3,

Speaker:

correct, correct.

Speaker:

Like, yeah, that's why I was saying it's like a special, like reserve area.

Speaker:

NS three.

Speaker:

Yeah.

Speaker:

it's

Speaker:

That's for, that's for a lot of safe safety reasons, right?

Speaker:

Yeah.

Speaker:

It's called a snapshot, but it honors a lot of our backup

Speaker:

with a big B requirements.

Speaker:

Yeah, because it's an actual copy, you can specify that it be sent to a, to

Speaker:

another region, to another account.

Speaker:

Right?

Speaker:

And that's what I wanted.

Speaker:

I want it in another account.

Speaker:

I want it in another region.

Speaker:

I don't want you to just do an EBS snapshot, for example, to the

Speaker:

same availability zone, uh, that.

Speaker:

Isn't, doesn't really follow the basic 3, 2, 1 rule, which is

Speaker:

something we talk about a lot.

Speaker:

Yeah.

Speaker:

But I do, I do think it's important to understand that a snapshot in,

Speaker:

in A AWS is so much, most, so much closer to what I would call a backup.

Speaker:

In fact, depending on how you do it, it definitely is a backup

Speaker:

than what we typically talk about when we say snapshots.

Speaker:

Right.

Speaker:

And, and it's interesting because there are vendors that have made

Speaker:

a, a deal of, you know, they're like snapshots are not backup.

Speaker:

And they've been saying that for so long that they continue to say that.

Speaker:

When what we're really talking about is AWS when it really is

Speaker:

a snap, it really is a backup.

Speaker:

it's interesting you bring this point up because think other vendors, other

Speaker:

traditional storage vendors are also now starting to go the same route

Speaker:

where they're saying our snapshots can now be offloaded into object storage.

Speaker:

Right.

Speaker:

Yes.

Speaker:

I, yeah, I have seen some of the, some vendors do that.

Speaker:

Yeah.

Speaker:

Right, which is very similar to what AWS has been doing, but I think

Speaker:

they still call them snapshots.

Speaker:

Right?

Speaker:

So

Speaker:

Yeah.

Speaker:

of this, you have to, I think it's important as administrator, an IT

Speaker:

person to really ask the question.

Speaker:

When someone says snapshot, what do they mean?

Speaker:

Yeah.

Speaker:

Right.

Speaker:

I'm gonna, and we had, we used the phrase snapshot backup in this,

Speaker:

um, in the title of this episode.

Speaker:

And this is a snapshot backup, right?

Speaker:

So it, it's some would see snapshot backup as like a, like a oxymoron,

Speaker:

like, like military intelligence, you know, um, that, you know,

Speaker:

two words that can't go together.

Speaker:

But if by snapshot you mean what they do in AWS and I. Similar, uh,

Speaker:

you know, other cloud vendors, then I'm fine with calling that a backup.

Speaker:

Just make sure, so the question is, how do you make a snapshot backup?

Speaker:

Well, there's two ways.

Speaker:

One is if you're talking the traditional type of, you know, storage snapshots,

Speaker:

you need to copy that snapshot to another, uh, storage array.

Speaker:

Hopefully one that's offsite.

Speaker:

Um, hopefully one, you know, my dream would be.

Speaker:

Is to another vendor or you, then you, you, you change the

Speaker:

form of the snapshot, right?

Speaker:

You know, you're doing, you're doing, you know, filer to filer and then you're,

Speaker:

you're backing that up to some other, uh.

Speaker:

Object store

Speaker:

system, right?

Speaker:

Yeah.

Speaker:

might do NDMP, who, you know somewhere, uh, Steven, uh,

Speaker:

his, his ears are perking up.

Speaker:

Um, the, um, uh, anyway, but if it's, but if it's, if it's a cloud vendor,

Speaker:

typically, and again, I can really only speak with, with authority and

Speaker:

AWS, but from what I've seen, the other cloud vendors are very similar.

Speaker:

When you take a snapshot in AWS, you're actually taking a backup.

Speaker:

And when you're doing that.

Speaker:

You can use AWS backup to sort of control all of this, which is AWS backup is

Speaker:

really just a control plane for all the other stuff that's going on, and

Speaker:

you can make sure that you know that you're following the 3, 2, 1 rules.

Speaker:

You have a different account, different availability zone, different region even.

Speaker:

Um, yes, it makes it cost more, but it actually makes it a real backup.

Speaker:

So, questions for you.

Speaker:

Yeah.

Speaker:

So you mentioned that sort of doing snapshots, replicating it from

Speaker:

one filer to another filer doesn't quite meet the rules of the two.

Speaker:

Right?

Speaker:

In 3, 2, 1, backup.

Speaker:

Uh, in the 3, 2, 1 rule.

Speaker:

What if so many of these vendors now allow you to run virtualized

Speaker:

instances in public clouds?

Speaker:

Mm-hmm.

Speaker:

So I could run a NetApp instance in AWS

Speaker:

Yeah.

Speaker:

My answer is no.

Speaker:

I.

Speaker:

because it's still the same software version.

Speaker:

Yeah.

Speaker:

Okay.

Speaker:

Yeah.

Speaker:

Now AWS

Speaker:

it's better.

Speaker:

Better, you know, good, better, best.

Speaker:

It's better than the other thing because at least it

Speaker:

isolates you from the hardware.

Speaker:

But it's still, the os still the same os.

Speaker:

And would you also consider the same like AWS offers file systems, right?

Speaker:

So they have like support for NetApp by FSX.

Speaker:

Would you consider replicate if it's, I'm not even sure

Speaker:

Yeah, I don't, I don't know.

Speaker:

I don't know if I can speak to that.

Speaker:

Right.

Speaker:

I don't know if I can speak to that.

Speaker:

Right.

Speaker:

And then, and then

Speaker:

do you have to be for the two is my question.

Speaker:

I, I, again, you're, you're just trying to, it, it's sort of a

Speaker:

good, better, best thing, right?

Speaker:

The, the, the more different you can be, the better you are.

Speaker:

It's difficult in this cloud world, right.

Speaker:

Um, the, um, and some would say, well, isn't a w aren't AWS snapshots the same?

Speaker:

And it's like.

Speaker:

They're actually a little bit different because it is a full image

Speaker:

copy, um, and it's stored in S3.

Speaker:

If something were to happen to your EBS volume because of a bug in EBS,

Speaker:

you could still use that snapshot, which is stored in a completely

Speaker:

different system, which wouldn't have the same bug and store that in.

Speaker:

You could restore that into EBS.

Speaker:

that your volume wasn't corrupted by some EBS bug

Speaker:

Well, but you're, but S3 isn't EBS.

Speaker:

no.

Speaker:

But when

Speaker:

Oh, you mean, you mean before?

Speaker:

Well, if it was created, if it was created, if it was corrupted

Speaker:

by the EBSB, then you know Yeah.

Speaker:

You're, that's gonna happen no matter what you do.

Speaker:

So, so the I, I like where you're going, Curtis.

Speaker:

I think there's also sort of the practicality aspect that we have to

Speaker:

also look out for, because ideally, like you said, right vendor, you

Speaker:

have multiple vendors, right?

Speaker:

You're using different technologies, but then you have to balance that with

Speaker:

pr, sort of the practicality, right?

Speaker:

Are you gonna be able to understand all these various technologies,

Speaker:

build out the skillsets, integrate it, pay for it, right?

Speaker:

We all know how small backup budgets are versus production budgets.

Speaker:

Yeah.

Speaker:

Yeah, yeah,

Speaker:

just.

Speaker:

And, and I've always tried, you know, throughout my career to try to be.

Speaker:

To say, look, if you're asking me my opinion, you know I'm

Speaker:

giving, I'm giving you the bar.

Speaker:

Right, right.

Speaker:

And you know, and I understand that people have to, they have to, they have

Speaker:

to live in the real world where, where backup is not the most important thing.

Speaker:

Ah, it hurts me to say that.

Speaker:

Um, right.

Speaker:

Um,

Speaker:

but at the same time, maybe there are certain use cases where

Speaker:

you can focus on it because of the high value of the data or

Speaker:

Yeah.

Speaker:

like that, where it is important to have

Speaker:

Yeah,

Speaker:

type solution.

Speaker:

also want to add, you know, we talk a lot about the 3, 2, 1 rule, and I

Speaker:

say that because the 3, 2, 1, like if it doesn't follow the 3, 2, 1 rule

Speaker:

and it's just not a backup, right?

Speaker:

I'll say the number one.

Speaker:

Number two, I think I'd be remiss to say that also I. You know,

Speaker:

we're starting to talk about things like the 3, 3, 2, 1, 1 0.

Speaker:

You know, you do want at least one of your backups, your copies

Speaker:

to be on immutable storage.

Speaker:

Right.

Speaker:

To be on truly immutable storage.

Speaker:

One that even you can't delete even if you want to.

Speaker:

Right.

Speaker:

Um, because only then is that backup, uh, protected against a ransomware attack.

Speaker:

Yeah.

Speaker:

Or a, or a, or a direct bad actor.

Speaker:

You know, a, um, what's the, what do, what do we call it?

Speaker:

Um.

Speaker:

threat.

Speaker:

Thank you.

Speaker:

You know?

Speaker:

No, there's a. Uh, uh, a rogue admin, right?

Speaker:

Uh, you know, a rogue admin, either a rogue admin, right?

Speaker:

'cause there have been rogue admin stories, you know, uh, but also someone

Speaker:

who is able to gain access to your administrative account and then go

Speaker:

and delete all your backups you need.

Speaker:

Only if even you can't delete it, even if you want to, is a backup, truly immutable.

Speaker:

Um, and so you can do that with snapshots.

Speaker:

You just need to copy them into something else.

Speaker:

Yeah.

Speaker:

All right.

Speaker:

This was fun.

Speaker:

Yay.

Speaker:

Welcome back, Curtis.

Speaker:

Yeah.

Speaker:

And our, our lag wasn't too bad on our thing.

Speaker:

Hopefully our QOS did its job and hopefully our recording, uh, works.

Speaker:

And with that, that is a wrap.