Microsoft Data Protection Manager: Pros and cons

Now that Data Protection Manager (DPM) is available, what can it do and what are its limitations? talked with a Microsoft DPM official to get some answers.

NEW YORK -- After a year of hype, Microsoft Corp. is finally shipping its disk-based backup product, Data Protection Manager (DPM) 2006, which analysts say is rudimentary at best, but will meet the needs of small Windows shops.

Unveiled at Storage Decisions today, DPM costs $950 per server, which includes agents for three file servers. Put simply, the product sits between the file servers being backed up and a traditional tape system. Once installed and configured, it can take up to eight snapshots per day of those file servers, enabling users to recover directly from disk instead of the tiresome process of recovering from tape.

Ben Matheson, group product manager for DPM, answered some of our questions about the product.

Architecture issues

Right now, DPM backs up files only. When will it support Exchange and SQL Server?

Ben Matheson: In version 2.0.

When's that coming out?

Matheson: It is two years away -- second half of 2007.

Is the three-host limit to each DPM server a technical limitation or a licensing issue? How much do additional host licenses cost and what is the maximum limit number of file servers each DPM server can support?

Matheson: The three agent per DPM server only refers to the number of agents that come licensed/bundled with the DPM boxed product. There is no technical limit to the number of agents a DPM server can support. You can easily buy more agents (ERP roughly $150 each) to scale up to protecting more file servers with DPM. There is no hard coded limit to the number of agents each DPM server can support.

How do you manage multiple DPMs? Can you configure them all from one console?

Matheson: There is a DPM pack for Microsoft Operations Manager (MOM), which is a monitoring product that works with all your servers: file servers, Exchange servers, SQL servers. You have to 'terminal server in' to manage configuration and setup. Eventually, we will add more advanced functionality for multiple machine management, but for now you have to "TS in.".

How many DPM servers can MOM manager?

Matheson: MOM can monitor hundreds of servers. So if the company can backup 30 file servers per DPM server you can easily see how even having a MOM server manage 10 DPM servers – that gives you 300 file servers being monitored – so it can really scale up easily. MOM wont be the bottleneck on this.

Windows Server 2003 lets you create local Volume Shadow Copy Services (VSS) snapshots on your file server. Why do you need DPM to do recovery?

Matheson: DPM builds upon the shadow copy services. There are drawbacks to snapshots that are maintained on the same physical server. If there's a failure, you lose all snapshots. By replicating to DPM, users get another tier of protection for shared folders. DPM protects against hardware failures as well as accidental deletion of files. It also centralizes backups to one server, making backup more efficient from a scheduling standpoint. Also, VSS is only available on Windows 2003.

Matheson: Disk-based backup improves data recovery for users, but it also means they need to buy more disk storage, which adds up. Does DPM server support single instancing?

Matheson: We do not. It will be available in Storage Server R2 at the end of the first quarter, 2006. It will be turned on by default and recognizes files that are the same, only storing them once.

Can DPM back up files that are in use? If it can, how do you maintain consistency of these files?

Matheson: Absolutely. We have a file system filter agent that does not get disrupted by open files. The agent sits on the file server, and any time you write to that file system, we grab the bytes and record changes to the protected data in a synchronization log on each protected volume. During synchronization, these changes are transferred to a transfer log on the DPM server and then applied to the replica to synchronize the replica with the data sources.

This comes with the product at no extra charge, unlike other products on the market. We replicate the log to DPM server every hour.

OK, so if I replicate at noon, and my server blows up at 12:30 [p.m.], I lose 30 minutes of data. Is that right?

Matheson: Correct. But with a tape-based solution, you'd have lost a whole day. We have check-pointing in the product, too -- meaning that if the network fails at 12.02 [p.m.], DPM knows when the last server was replicated and doesn't have to start over again.

What happens if a backup from DPM to tape, using a third-party product, fails? Does DPM know?

Matheson: You have to reply on tools inherent in your tape backup product for that. There are three vendors providing the archive component for DPM -- Yosemite Technologies, Computer Associates and CommVault. You will have to reply on their management console if the jobs failed. Veritas will have a Backup Exec agent for DPM, too.

What is the limit on the number of snapshots? Why is there a limit?

Matheson: It can take up to eight snapshots per day and a maximum of 64 per volume. If you took one per day, you could keep three months worth [of snapshots on DPM]. If you took three per day, you could keep one month. We did some research and found that 90% of recoveries happen within a month. Depending on what customers tell us, we will modify this.

What happens to the old snapshot once it reaches the limit?

Matheson: It's a first-in first-out process.

Recovery process

Thinking about the recovery process, let's say I have 10,000 files on DPM that I want to restore back to my file server. How long will it take?

Matheson: Depends on how big your files are, how fast your network is. We've done benchmarks against tape backup and DPM is 12X faster than tape. The test showed DPM could restore a 100 MB file in 30 seconds. Whereas it took a tape system five minutes and 48 seconds to restore the same 100 MB file. And that was with the tape already in the drive and queued up. More often than not, you'd probably have to go off site to get that tape, which could take hours.

Can I do policy-based recovery? For example, I want to recover all files that my accounting team had been working on in the last 24 hours.

Matheson: No we don't have that functionality. If we hear that customers want that, we will develop it.

Licensing issues

Does installing DPM mean I require fewer backup licenses on my file servers?

Matheson: Yes, that's correct.

Does this mean Microsoft is trying to take Veritas out of the backup business?

Matheson: No, we never focus on the competition. We are focused on the customer. Lots of people are entering the disk-based backup market, which says that there is a lot of pain in tape-based backup. Customers need a better solution.

The reality is that you are taking away license revenue from Veritas.

Matheson: Could be.

Are you going to let customers download DPM as was the case with the beta, or are you only going to sell it through your OEM partners?

Matheson: The evaluation period for DPM is time-bombed. Customers can download it, but after 120 days, they have to purchase a new license or stop using it. It will be available through all our traditional channels, like CDW and TechData. Our OEM partners so far include HP, Quantum and Fujitsu Siemens, who will see preconfigured appliances based on DPM.

How many DPM betas were downloaded?

Matheson: Sixty thousand.

Users have to maintain and manage yet another Microsoft server. Could this not have been part of Windows?

Matheson: As a feature, I guess it could have been. The industry has a separate standalone product based on backup. Customers can use shadow copy for shared folders in Windows 2003, but for a centralized model, DPM is the way to go.

Why would I buy DPM when Veritas sells a similar product that takes snaps of heterogeneous servers for the same price?

Matheson: I haven't seen Veritas' pricing. But we offer an incredible amount of value, including integration with other Microsoft Windows Server products. For example, integration with Active Directory to discover all servers in the environment, to provide the right security levels so that users have access to the right files, integration with MOM, end-user recovery from Windows client, the stack of our products -- works well. Customers don't want something that's rip and replace.

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