TECH LINE: Disk Signature Disaster
\nSaving yourself some pain when replacing failed cluster disks.<\/p>\n
By Chris Wolf<\/p>\n
Chris: We recently had a hard disk fail on or Windows 2003
\ncluster and it was an absolute nightmare. I replaced the failed
\ndisk and could not get the cluster server to recognize the new
\ndisk in order to restore the missing disk files from backup. I
\nassigned the same drive letter to the new disk, but each time I
\nwould try and bring the disk resource online, it would fail.
\n<\/p>\n
Since we were in a pinch, we decided to scrap the cluster and
\nstart again from scratch. After rebuilding the cluster, we were
\nable to restore files to the two cluster virtual servers from
\nbackup. I’m sure there has to be an easier way to recover a
\nfailed cluster. What else could I have done?
\n— James<\/p>\n
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After talking with James, I learned that his cluster ran two
\nvirtual servers: a virtual file server and a virtual print
\nserver. Each virtual server resided in its own group on the
\ncluster. With this relatively simple setup, rebuilding his
\ncluster did not take a long time. Since the point of having a
\ncluster is high availability, taking down an entire cluster is
\nnever the best option. The reason James had this problem is due
\nto how Microsoft Cluster Service (MSCS) treats disk signatures. <\/p>\n
The MSCS associates physical disk resources by the disk
\nsignature that’s written to each physical disk when the disk is
\ninitialized by a Windows OS. If you replace a physical disk
\nwithin the cluster, the Cluster service will see the original
\ndisk as failed and will not even see the new disk. To have the
\nnew disk seen as the original disk, the original disk’s
\nsignature reference in the cluster configuration must match the
\nnew disk. While there are a few tools that can do this, by far
\nthe easiest method is to associate the new disk with the failed
\ndisk is by running the Server Cluster Recovery Utility. <\/p>\n
The Server Cluster Recovery Utility is included in the Windows
\nServer 2003 Resource Kit and can be downloaded from Microsoft at
\nhttp:\/\/www.microsoft.com\/downloads . This tool is especially
\nuseful when replacing a shared cluster disk or in a disaster
\nrecovery scenario when a cluster is being rebuilt using new
\nphysical disk resources. Oftentimes, after a cluster quorum is
\nrestored, physical disk resources will still not be able to come
\nonline. That’s because the signature for the disks stored in the
\ncluster configuration does not match the signature of the new
\ndisks. In these instances, the Server Cluster Recovery Utility
\ncan be used to return the disks to a usable state. <\/p>\n
To use the Server Cluster Recovery Utility, first install the
\nreplacement disk and use Disk Management to initialize and
\nformat the new disk as NTFS. Then go to Cluster Administrator
\nand create a new resource for the newly added physical disk.
\nHere are the steps:<\/p>\n
1. In Cluster Administrator, right-click the Resources
\n container, select New, and then click Resource.
\n2. In the New Resource dialog box, enter a name for the
\n new resource, select “Physical Disk” as the resource
\n type, and then select the group in which to
\n associate the resource.
\n3. Select the possible owners for the disk (same as
\n original disk) and click Next.
\n4. In the Dependencies dialog box, click Next.
\n5. The newly added disk should be displayed in the Disk
\n drop-down menu. Select the disk and click Finish.<\/p>\n
With the newly installed disk associated with the cluster, you can
\nnow use it to replace the failed disk resource. To do this, first
\nensure that the Windows Server 2003 Resource Kit Tools are
\ninstalled on the node you plan to perform the procedure on and
\nthen follow these steps:<\/p>\n
1. Run clusterrecovery.exe to open the Server Cluster
\n Recovery Utility.
\n2. Once the tool opens, enter the name of your cluster
\n in the Cluster Name field. Then select the “Replace
\n a physical disk resource” radio button and
\n click Next.
\n3. Select the original (failed) disk in the “Old
\n physical disk resource” drop-down menu and then
\n select the new physical disk from the “New physical
\n disk resource” drop-down menu. Then click Replace.
\n4. Next you are given a friendly reminder from the
\n Server Cluster Recovery Utility to delete the
\n original disk resource and then change the drive
\n letter of the new disk resource so that it matches
\n the drive letter assigned to the original (failed)
\n disk. Click OK.
\n5. Click Exit to close the Server Cluster
\n Recovery Utility.
\n6. In Cluster Administrator, locate the failed disk
\n resource. The failed disk resource will be easy to
\n spot in Cluster Administrator because it will have
\n the word “(lost)” next to its name. Right-click on
\n the lost resource and select Delete. When prompted
\n to confirm, click Yes.
\n7. Use Disk Management to change the drive letter
\n associated with the new disk. <\/p>\n
At this point, you can bring the virtual server resources back
\nonline and restore the original virtual server data from backup. <\/p>\n
Note that some resources may fail to come online. For example, a
\nFile Share resource will fail if the original folder that the
\nresource is associated with is not present. After the backup is
\nrestored, you will be able to bring all resources in the group
\n(virtual server) online. Also keep in mind that depending on how
\nyour enterprise back-up software is configured, you’ll most
\nlikely need to reinstall your back-up agent software into the
\nvirtual server in order to perform the restore. <\/p>\n
Before the days of the Server Cluster Recovery Utility, cluster
\ndisk recovery was fraught with pain. As soon as I would hear of
\na problem, my mind would instantly fill up with the burnt tooth
\nsmell that serves as an ominous sign at most dentist offices.
\nNow when I hear of a cluster disk failure, I just smile from
\near to ear. This could mean that either I’m comforted by the
\nease of the Server Cluster Recovery Utility, or that my sanity
\nis starting to return! <\/p>\n","protected":false},"excerpt":{"rendered":"
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