Remote storage disaster recovery for Windows 2000 networks

If data is saved on remote storage tapes, you're safe, right? Well, maybe not. Brien Posey reminds you can things can go wrong when tapes are constantly overwritten, and he explains how to avoid and recover from storage disasters.

By Brien M. Posey | Posted Sep 12, 2000
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When it comes to working with remote storage, many administrators have a false sense of security. After all, we've always been taught that if it's on tape, it must be safe. Remember that a remote storage tape functions differently from a backup tape. Remote storage tapes are constantly being overwritten and are usually constantly available online. Backup tapes, on the other hand, are written to and then removed and stored in a safe place. Because of the nature of remote storage, a lot can go wrong. This is even more true when you consider that the Windows 2000 implementation of remote storage is new, and administrators are more likely to make a mistake then they would be if they were using familiar technology. In this article, I'll discuss some of the things that can go wrong with remote storage media and some techniques you can use to recover from such disasters.

Backing up Windows 2000

I've seen many instances in which network administrators backed up the data from a server, but not the operating system. If you're using remote storage, this isn't a practice that you want to engage in. Sure, the biggest part of backing up remote storage deals with the tapes; but a copy of the remote storage database actually resides at %SYSTEMROOT%\SYSTEM32\REMOTESTORAGE. A duplicate copy of this database also resides on the remote storage tape. However, if you were to lose the main copy, the process of retrieving the copy from tape is extremely long and complicated. If you get desperate and have to pull the copy from tape, you can find instructions for doing so in the Microsoft Knowledge Base.

Single tape drive techniques

Backing up and restoring remote storage is easiest if you have two identical tape drives. However, you can still make a backup on systems containing a single tape drive. To do so, you'll have to use a tape drive attached to another machine to back up remote storage. In such a situation, you can back up remote storage files in the same manner you would back up any other files. (It's important to do this from time to time even if you have multiple tape drives, because you can't restore the remote storage database to another computer.) If you ever need to restore files from remote storage to another system because of low hard disk space, the restoration will work only if the files were backed up using this method.

Multiple tape drive techniques

If you have two identical tape drives attached to the server, you can actually copy your remote storage tapes. Keep in mind that I recommend still performing your normal nightly backup, just as you would on a single tape drive system. However, making copies of the remote storage tapes is a good way to supplement your disaster recovery library. The great part about doing this is that if you have a really big disaster, you can restore your operating system (and the remote storage database that it contains) from tape. After that's done, you don't have to worry about restoring the remote storage tape. Instead, you can just insert the copy you made, click a few buttons, and you're back in business.

Working with remote storage media

Multiple media masters
It's possible to have more than one media master. For example, you would have multiple media masters if you had too much data in remote storage to fit onto a single tape. A group of media masters is referred to as a master set.
When using remote storage, the tape that contains all the remote storage files is called the media master. Keep in mind that the media master is basically unprotected from any sort of calamity. After all, you can't set up a RAID array for remote storage media. Because of this fact, Microsoft has built into Windows 2000 the ability to create media copies, which are copies of the media master.

Creating media copies is a simple process. Windows 2000 doesn't require you to go through a complex copy process. Instead, simply specify the number of copies you want, and Windows does the rest. All you have to do is make sure the free media pool contains enough blank tapes to create the number of copies you've requested. (This is where a tape auto loader comes in handy.)

To create a media copy set, open the Microsoft Management Console (MMC) and load the Remote Storage snap-in. Next, right-click on the Remote Storage root and select the Properties command from the resulting context menu. Select the Media Copies tab from the resulting properties sheet and specify the number of copies you want to up to a maximum of three copies.

Before we move on, suppose for a moment that you decide you are creating too many copies. If this is the case, you can go into the MMC and lower the number of media copies you want to create. However, doing this doesn't affect any of the tapes you've already created--they are all still valid. If you need to reclaim some tapes, you need to follow the following procedure to delete them.

To delete a media copy, open the MMC and select the Media folder. Next, right-click on the media master that's associated with the media copy you want to delete, and select the Media Copies command from the resulting context menu. Select the media copy you want to delete and click Delete Copy.

Now that you know a bit about how to work with media copies, let's assume that your media master gets eaten by a hungry tape drive. After replacing the drive, you'll need to turn your most recent media copy into a media master. To do so, open the MMC and load the Remote Storage snap-in. Next, open the Media folder, right-click on the most recently synchronized media copy, and select the Media Copies command. Go to the Recovery tab and click the Recreate Master button. It's that easy.

Other tasks

So far, I've discussed procedures for backing up remote storage files under a variety of conditions. However, all the backups in the world won't do you any good unless the data you're backing up is good. I recommend that you occasionally verify the integrity of your remote storage system. Doing so involves checking out the place holders and cached files to make sure they are still linked to their corresponding files on the tape.

When you set up Remote Storage, it automatically creates a validation schedule. Normally, the default validation schedule is enough to keep things running smoothly. However, you can use the Remote Storage MMC snap-in to check out this schedule. If need be, set the schedule to run more frequently. If you're implementing Remote Storage on multiple volumes, you should also check to make sure that the consistency check is being run against all necessary volumes.

Final words of caution

In the previous above, I explained the remote storage validation process. However, if you just lost a hard disk and have to reload Windows 2000 from scratch, don't be too hasty about performing the validation process. If you use incremental or differential backups, be sure that you've restored each backup before running the validation. //

Brien M. Posey is an MCSE who works as a freelance writer and as the Director of Information Systems for a national chain of health care facilities. His past experience includes working as a network engineer for the Department of Defense. Because of the extremely high volume of e-mail that Brien receives, it's impossible for him to respond to every message, although he does read them all.

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