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.
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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.