The Backup Blog

Welcome Aboard Data Domain

As of this morning, it is official, EMC has acquired a majority intrest in Data Domain, and from here forward they will be run as an product division within EMC, with the DD structure remaining intact, and Frank Slootman will head the new division.

So first things first: welcome aboard to all Data Domain employees and customers. As I have said here previously, I think EMC is a great place to work, and I believe that you will all find that to be the case too. To Data Domain customers--I think you will find EMC has a lot to offer, that we really care about our customers, and that we have a lot to talk about.

Having said that, I think most people will have two big questions for EMC: 1) How do DD and Avamar fit together? And why do you guys now have two different deduplication technologies? 2) How is DD going to fit within a unified product line?

The answers here I will give are my personal answers. This shouldn't be mistaken for some sort of official EMC statement, or any sort of look into our product roadmap! Having said that...

In answers to the first question(s): my firm belief is that source deduplication (Avamar) and target deduplication (Data Domain) are entirely complementary. Complementary in both a business sense, and a technology sense.

EMC DL and Oracle RMAN Filters

The second new feature of the DL that I would like to highlight this week is even more straight forward than the last: Oracle Filters. These Oracle Filters give the DL a nearly 2:1 capacity advantage over competitive systems when backing up Oracle RMAN data streams.

To understand what the Oracle Filter is, we need to step back a second and understand how deduplication works. When a data stream is sent to a deduplication appliance, to achieve optimal deduplication efficiency, that appliance should apply a filter that is specific to the type of backup application and data type that is being backed up.

Deduplication Efficiency

There are a lot of different deduplication choices these days. And lots of ways to shove these technologies into places they weren't meant to go (or shouldn't have been). Even if we focus just on deduplication for backup--and this is the backup blog!--then there are still a couple big choices to make.

The biggest choice, of course, is do you want to deduplicate at the source or the target?

In EMC product terms, do you want to use Avamar or DL3D? Just for fun, lets note that there are no real significant alternatives in the source deduplication space these days (as it is my perception that Symantec's PureDisk is retreating to a target based model). On the target side, Data Domain retains a strong position but continues to lose significant market share to EMC.

DL4000 3D Explained, Part 3

In an effort to respond to the observations of W. Curtis Preston in his posts here, here and his comments here; and additionally in an effort to satisfy those of you who wanted a more direct response to those observations, I post some (final?!) comments below. Two comments first:

1. The dialogue has been going on for a long time, and the material comes from a few different sources. So the responses are more point form, and may move from point to point without a lot of regard for the previous point--there is no longer any strong unifying theme.
2. All the material below should, in my opinion, be placed firmly in the context of my VTL: What Matters? post. I feel quite strongly that those are the over-riding concerns, and that the following material is interesting primarily in terms of its' ability to determine how well the device meets the criteria described in "What Matters?"

With that said, on with the show!

VTL: What Matters?

As a result of some of the longish posts, comments, and replies about the architecture and functionality of DL4000s with deduplication that I engaged in with Curtis Preston and others, I got to thinking.

My feeling was that Curtis was wrong, but not for any specific technical reason.

Sure, some of his points were wrong in my estimation. Some were right.

But even accounting for that, I had the feeling that the sum of his argument was more wrong than right, and more wrong than I could account for by simply saying that this or that specific point was wrong.

Put another way: the whole of his argument was less than the sum of its parts.

But why exactly he was wrong is, I think, interesting.

Mr. Preston is wrong because the discussion is not relevant. Not cogent to why somebody might choose to buy a particular virtual tape library, or deduplication device. So ultimately, it comes down to not so much that he is wrong, but that the whole discussion fundamentally misses the point, and is not relevant.

It doesn't pass the "so what?" test.

EMC and Quantum Strengthen Relationship

EMC and Quantum announced today that they were strengthening their relationship as EMC loaned Quantum $100m to refinance debt.

The significant thing about this is, to my mind, that it is a loan. Not a purchase of stock, not a take over or partial take over or any such thing. It is a loan, made to a partner that supplies EMC with some very important technology: deduplication software for backup.

The other important aspect of this is that it comes on the heels of a very successful quarter for Quantum; the EMC loan is a clear reflection of the confidence we have in the company and their technology. For Quantum, this allows them to focus on their technology, and growing their business.

The market seems to have reacted positively, as QTM is up 90% as of the time of this writing.

Does Global Deduplication Matter?

Curtis Preston penned something last week asking if global deduplication matters. I am not sure if Curtis would count me in the group that questions global deduplication's reality, or not...

Of course I believe it is real!

The real issues are actually two-fold: does it matter, and if so, how much?

Mr. Preston claims that it only matters if you back up more than 10-20 TB. Well, that is a pretty broad range. I would actually amend this to a more specific number: for a single EMC DL3000 that is 18 TB (12 hours of deduplication), and for a DL4000 with deduplication enabled it is 30 TB. Why the larger number? Because with deferred deduplication and faster ingest speeds, it is perfectly legitimate to deduplicate throughout the day. For the sake of operational realities, I am assuming you are deduplicating for 20 hours with this number. That still leaves ample time for other niceties, like restore, for example.

DL3D Adds OST Support

This one sort of snuck out the door: with the latest version of the DL3D code, EMC has added support for Symantec's OST initiative.

OST is a way for Symantec NetBackup to address "disk as disk" rather than as virtual tape. More important than this, in my mind, is the ability of an OST enabled device to replicate in a much more intelligent way, and in a way that tightly integrates with the backup application.

What do you need from Symantec? Well you need NetBackup v6.5. And you need the OST plug-in installed on any media server that is going to connect to the DL3D. Connection over IP (only) is supported. And in Symantec's parlance, the DL3D becomes a "storage server".

This storage server contains Logical Storage Units which are available to Media Servers. The Media Servers then access the pool of deduplicated storage on the DL3D as they would any other NFS or CIFS attached storage.

Why Do We Build A DL4000 3D?

I have had a lot of comments, mostly constructive, on some of posts about performance and the EDL 4000 3D. (The translation of that product name, by the way, is the EMC Disk Library 4000 with deduplication.) W. Curtis Preston has been one of the most vocal critics, and while I think he is dead wrong--nothing personal, Curtis, that is just my opinion of your opinion--I don't think his comments are so trivial that I am going to dismiss them out of hand. I also suspect that they are roughly congruent with the initial reaction some users might have to the device.

So I wanted to take the opportunity to address some of these comments in a more structured fashion than just the back-and-forth in the comments section. Giving Mr. Preston his due, I will quote him directly and then respond to the objections.

Avamar on a Roll

Avamar has done exceptionally well over the last year. The product has definitely come along, and happens to be hitting its stride at the same time that customers are realizing how problematic certain types of backup are: VMware in particular. All this has contributed to massive growth, and a sudden realization that source based deduplication is a powerful alternative to target based deduplication. It turns out that we at EMC aren't the only ones who feel this way. From a recent analyst report on Data Domain, we have the following:

"analysts see a problem looming on Data Domain's horizon: competition. Since data protection software is a highly saturated market, Slootman says the players are in a "ground war" over space in the data center. And EMC's (EMC) purchase of deduplication startup Avamar Technologies two years ago brought one of the data center's behemoths into the picture... Data Domain is still the dominant player in the field, and the company has kept innovating to ensure a superior offering."

So lets take a look at this. The analyst is acknowledging that Avamar is competing effectively against DD. And we are. Avamar works, and works very well. What is more, Avamar offers a couple of compelling values that DD can't: significantly reduced I/O and CPU utilization on the backup host. DD does nothing for either--you still use the same amount of CPU, the same amount of network bandwidth, and you are still tied to the mediocre capabilities of a traditional backup application in the VMware world.