DPM protects your data by using an agent to monitor changes to the data. The catch is that the agent is a requirement, and it won't work on just any server.
If your data is stored on a server running Windows 2000 with Service Pack 4 or higher, or if it's stored on a Windows 2003 Server, you shouldn't have any problems. But if your data is stored on an NT, Unix, Linux or NetWare server, you're out of luck. Since the DPM agent is not compatible with these types of servers, you cannot use DPM to protect the data they contain.
The same thing goes for network-attached storage (NAS). DPM cannot protect data stored on a NAS server. However, Windows Storage Server may be an exception, since it is based on Windows Server 2003 code and may possibly support DPM. (Note: I have not been able to locate any documentation that confirms or denies this.)
Now let's talk about the server itself. There are stringent requirements for the server. DPM requires the server to be running Windows Server 2003 with Service Pack 1 or higher (the 64-bit edition of Windows Server 2003 is not currently). The server must also have a minimum of two hard drives (either individual drives or arrays defined as a volume).
One of these drives is reserved for the Windows operating system and for the DPM
The server's role is also important. The server cannot be a domain controller, but must be a member of a domain. Likewise, you cannot run any applications on the DPM server other than DPM itself and standard applications such as anti-virus software.
DPM has some pretty hefty hardware requirements, and that's without taking into account the fact that Microsoft has traditionally been notorious for understating the hardware recommendations for its software. Microsoft recommends a server with a 1 GHz or faster processor, 1 GB of RAM, and disk space that is two to three times the size of the protected data.
Personally, I think Microsoft's recommendations might be a tad optimistic. I have not tried running DPM on a computer with a 1 GHz CPU, but I know it runs smoothly on my 3.2 GHz Pentium 4 server. I initially tried running DPM with 1 GB of RAM. DPM functioned flawlessly, but the user interface was a little slow. Giving the server another gigabyte of memory helped the speed issue.
Now for the disk space issue. Having a store available that is two to three times the size of the data that you are protecting is realistic, but you need to consider some other issues before deciding how much disk space to purchase.
One issue is that DPM stores multiple versions of each protected file. Suppose you make a change to a Word document. DPM keeps the original version of the file on hand along with the new version. DPM only records the bytes that have changed in the new version rather than recording the whole file so that it can save disk space, but frequently changing files still tends to consume a lot of space. The point is, you want to have enough free disk space that you can maintain a month's worth of file changes. DPM will work with less disk space, but the less disk space you have, the fewer file versions it maintains.
Another thing to consider: You shouldn't base your estimate on the amount of data you're protecting today. You will be protecting more data tomorrow, and you need to plan for that growth. I recommend estimating how much data you will have on hand a year from now and planning your disk space requirements based on that figure rather than on the size of your current data store.
One last issue regarding disk space is the requirement for two hard drives. Earlier I mentioned that one hard drive was reserved for the Windows operating system and for the DPM system files. That doesn't mean you can get away with using a small hard drive as the system drive. As I've said, it is important that you perform tape backups against your DPM server. But to do so, your server's system drive must have enough room for DPM-aware backup software and to store temporary copies of the DPM and the report database.
Microsoft recommends that your system drive contain free space equal to at least double the size of these databases. That's not as bad as it sounds. Granted I have a small office, but right now my databases amount to about 40 MB and I am protecting roughly 160 GB of data. However, most of this data is static; organizations with lots of constantly changing data can probably expect much larger databases.
As you can see, it is important to plan out your DPM server prior to actually deploying it. In my next story, I will walk you through the deployment process.
In my story Why DPM is replacing traditional disk-to-tape backups, I discussed the advantages that disk-based backup has over tape backups. A second story Deploying DPM requires server and storage planning, looked at some of the planning that needs to go into a DPM deployment prior to purchasing a server or attempting an installation.
Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server and IIS. He has served as CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. He writes regularly for SearchWinSystems.com and other TechTarget sites.
More information from SearchWinSystems.com
- Tip: Watch Deploying DPM requires server, storage planning
- Topics: Backups
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This was first published in May 2006