The Backup Blog

The Remote Office: CDP or Backup?

A colleague sent me the following link the other day: The Case Against Tape Backup. The link gets you to a white paper written by Double Take Software, which argues that using tape for remote office backup is a bad idea.

Their conclusion? That instead of tape, we should employ CDP software, and that this is much more cost effective.

Unfortunately the paper is deeply flawed. Don't get me wrong, I would be very happy if the general conclusions they drew were true. I would be just as happy if they were content to conclude only that tape was bad--meaning too expensive and too unreliable. 

However, they are not content to reach such a conclusion, and in their attempt to make the leap from "tape is bad" to "CDP is good" they go dramatically awry in two respects. First, they posit a false dichotomy. It is not like the only alternative to tape is CDP for remote backup. And, in fact, some of the solutions that they (conveniently) ignore, are substantially less expensive than their proposed CDP solution. Second, their financial reasoning is pretty badly flawed. And I have never been a fan of make your own solution look good by falsely making the alternative solution look bad.

However, I do think that following through the line of reasoning in the white paper is pretty interesting--and by doing so we can expose some better data about the costs of remote office backup and the alternatives to tape.

Putting The Pieces Together: Deduplication Technologies

Disclaimer: everything that follows is my opinion. In no way should it be mistaken for any sort of official EMC position. Any resemblance to that is purely coincidental.

Amidst the chaos and confusion of the EMC offer to buy Data Domain, I think the biggest unanswered question has been: why would EMC want to have three or four or five different deduplication technologies?

Truthfully, I think the question has a profoundly simple answer: because backup sucks.

Mmmm, irony.

Don't believe me? Show of hands: how many people actually like their existing backup application?

Given the name of this blog, and that I have spent the last 15 years plus on backup and recovery, I think I can appreciate the irony as well as any.

Even more ironic when we remember that Data Domain's original slogan was: tape sucks.

And by the way, there is a back handed answer in there as to why it makes sense for Data Domain to be acquired by somebody. If you claim that tape sucks, and you try to "fix" this with another piece of hardware, all you are really doing is building a better tape drive. You are trying to be StorageTek, only better. Where better means faster and cheaper. But does a faster and cheaper tape drive make backup suck less? Maybe. But probably not nearly as much as it could--if you had a broader perspective and reach with your technology roadmap, one that includes CDP, primary storage, a backup application, and some virtualization capability. More on what I would do with all that later. But one final question: if your objective is to fix backup, completely, and you think that you need access to all those components to do that, who is going to be in a better position to do this? EMC? Or NetApp?

Having said that, the biggest obstacle to fixing backup is not technology. It is inertia. It is cultural. It is fear of change. It is ingrained process. It is the fact that we have done things one way for so long that the reason we are going things has been forgotten.

Actual Deduplication Ratios

Or, does deduplication give you what you want?

I thought it would be an interesting exercise to try to correlate the voting in my poll (in the right hand column) with the actual results achieved by deduplication users. This should give us some indication of whether the technology is meeting the expectations of users.

So, after 199 votes, the results are in. The results were pretty consistent by geographic region, with about 2/3 of the votes coming from the USA (which pretty closely mirrors world-wide adoption of deduplication technologies).

Deduplication APIs?

Curtis Preston raised an interesting point over at Backup Central regarding the need for a common set of standards for the interaction of deduplication appliances and backup applications.

Now, on one hand I agree with Curtis' basic premise (even if I do slightly disagree with some of his historical characterizations). In fact, I have twice made pleas on this blog to similar effect, here and here. Having said that, I will readily admit that W. Curtis Preston is taking the request to the next level. Rather than just ask backup application vendors to implement the means to take advantage of the target side replica of a deduplication appliance, he is asking to community to have a common set of APIs, an open standard, around this.

So, a couple of things. First: everything in this post is strictly my opinion. Nothing in here has been read, endorsed, or reviewed by anybody else at EMC. Having said that: Mr. Preston is right. This is needed, and needed badly. I have been saying it for a while, and his request is the logical extension of the arguments I have made before. So rather than arguing with Curtis about history or debating how to do this, let me state clearly which I think such an effort should achieve, with the hope that this can constructively advance the conversation.

Backup and the Downturn

I haven't talked about the downturn at all, because, well, a) it is just depressing, and b) there doesn't seem to be much point. However, I did see an interesting article over at Search Storage that mentions that backup is the last service likely to be touched or impacted negatively by spending cuts.

I guess that is good news for those of us that have specialized in the area. Anecdotally, I can vouch that I have been no less busy for the last couple of quarters than I have been in previous years during year end. If anybody has any experiences to share in that regard, please post up. It would be interesting to build a picture of our backup and recovery industry from participants that would show how much (or how little) the current economic slowdown is impacting us.

Deduplication and Replication

Some time ago I wrote a post Peace, Love and Revolution about the issues that replicating deduplication appliances causes with backup applications. Some six months later, I thought it would be good to update the state of the nation and see what progress has been made.

To quickly refresh, the issue is this: how do you restore data from a deduplication appliance that is the target for replication--when it is the appliances that is managing the replication process and not the backup application. (And to be fair, this is not an issue unique to deduplication: the exact same problems apply if you are just using virtual tape. The issue just happens to be more pressing with deduplication because if it is "just" virtual tape, I can use the backup application to manage replication and not cost myself any bandwidth; with deduplication, if I use the backup application I miss out on the 95% bandwidth savings that deduplication replication promises.)

So They Do Understand...

It took a while, but the nice folks over at NetApp have attempted to describe what exactly Tape Smart Sizing does. I could be wrong, but I think they agree with me. I guess since I agreed with them that using single parity RAID on a VTL with 1 TB drives is dangerous (yes their Near Store VTL does exactly that...) they decided to return the favor? Perhaps...

In any event, Absolute Architect decided to pen a response which was completely complementary to my analysis. To the best of my understanding, she agrees that Tape Smart Sizing is a "confusing ... technology that won't remotely impact your life" (her words). Which pretty closely echoes my claim that it is "unnecessary and irrelevant". And I mean that literally. For most, if not all organizations, the "feature" is either unnecessary, irrelevant, or both.

Much like a square wheel bike.

Do square wheels work? Yes, if the ground is shaped like an inverted catenary. Are square wheels necessary or relevant? Not even remotely.

The analogy is perfect. Does Tape Smart sizing work? Yes. Is Tape Smart Sizing necessary or relevant? Not even remotely.

The good stuff is always in the why.

Tape Smart Sizing: Another NetApp Myth

One of the more interesting replies to my recent discussion of NetApp's dangerous VTL--which NetApp apparently feels is likely to cause significant loss of backup data--concerned the concept of "tape smart sizing". To quote NetApp's CTO: "I can also confirm that Tape Smart Sizing works exactly as advertised."

Since I dismissed it as little more than a David Blaine type trick, it might be useful to ask: what exactly is advertised? Again, just quoting NetApp:

"[tape smart sizing] sample[s] the data for compressibility as it’s being written to the VTL and then dynamically adjust the size of that virtual tape to match the estimated compressed capacity of the physical tape it will be written to. The LTO-3 virtual tape is now automatically adjusted depending on what type of data is being written to it and how it will compress in the Real-Tape World. Welcome to not wasting money or space on extra physical tapes when using a VTL."

Incidentally, NetApp also claims that:

Every other VTL out there requires you to to set a fixed size on the virtual tape when configuring the virtual library.

The consequence of this is, according to NetApp, that if you write 200 GB data that is 2:1 compressible to any other VTL, you will use 200 GB of disk space; write it to tape, and you use 100 GB of tape (because tape is compressed). So, it seems that you would require 2 virtual LTO-1 cartridges. Take those 2 virtual cartridges, and they will each half fill a physical cartridge. Thus, wasted tape.

So we have two different bloggers claiming that tape smart sizing is useful, and unique in terms of its ability to save space of physical media. Basically, that "every other VTL" will require that you waste physical tape space as described above.

Let me state this unequivocally, and for the record: this is not true. EMC's virtual tape products have no such issue.

If Tape is Dead...

Then it should be starring in a George Romero movie.

I saw this little snippit over on blocksandfiles: Quantum just sold their 20,000th i500. That is a lot of tape drives and robots.

Lets put this in perspective.

Speaking in very rough numbers, I think there are three vendors of virtual tape solutions and deduplication solutions that claim to have sold more than 5,000 systems: EMC, IBM, and Sun. As I have remarked before, IBM and Sun base that claim primarily on sales of mainframe virtual tape systems--if you look at their performance in the open systems world, the numbers are far less impressive. Probably by an order of magnitude or so.

Other vendors have sold so few VTLs that they are essentially insignificant in the numbers game: NetApp, Copan, Sepaton, etc. don't amount of much. (Note that this isn't a comment on the technical merits of their products, just an observation, based on limited data, about their sales success.)

Toronto Seminar

This August 27th I will be speaking in Toronto, Canada on the subject of deduplication. The session will focus on two key technologies: source deduplication--embodied in Avamar for our purposes, and target deduplication--with the EMC 3D deduplication appliances. I will spend some time as well on how each of these technologies is relevant to VMware backup. Finally, I will talk briefly about Total Cost of Ownership of these new deduplication solutions versus traditional backup solutions that use tape.

Yes, it is partially a marketing session, but it will be technical--maybe not to the degree that I sometimes get into in this blog, but certainly not the typical marketing fluff either. Of course, you are welcome to grab me after the session, and we can take the conversation up a notch or down a notch, which ever is your preference. Or you can just show up and heckle!

Follow the "continue reading" link for a full description, or just click here to register.