| Written by Mitch Ross,
on 05-03-2007 15:25
|
Servers running DFS and Windows 2003 R2 experience very slow backups, and sometimes no backups at all.
  Symantec changed how they select and backup files on servers running DFS (DFSR), on Windows 2003 R2. Previously, files could be selected just as any other file. Starting with 10d Hotfix 29 & 31 (both of which are included in SP2), and all levels of 11d, Backup Exec requires the use of the "DFSR Writer" when backing up and restoring folders used by DFS. Implications of this are: - Files replicated by DFS can on longer be directly backed up (i.e. D:\DSFRoot\Data\*.*)
- Attempts to do so fail without an error message or warning. Jobs show a byte count of a few Kb of overhead, but 0 bytes of data.
- The new "proper" way to select DFS replicated is convoluted and not obvious. Folders are buried 4 levels under "Shadow Copy Components", even if you don't run Shadow Copy on that server. See http://seer.entsupport.symantec.com/docs/281856.htm
- The new method results in drastic performance drops (Between 40% - 90% slower in tests). On one of our production servers, a nightly backup job went from 5 hours to over 22 hours.
- Backup performance with new method is highly impacted by users accessing the server.
- Backups from the new method now cannot be redirected when restoring
- Depending on your post-31 hotfix level, the new selections may disappear and all DFS backups fail after the first backup. See http://seer.entsupport.symantec.com/docs/284186.htm
Workarounds- Don't upgrade to SP2, Hotfix 29, Hotfix 31, or 11d.
- Stop the "DFS Replication" service when backups are running, using pre & post commands
Misc Comments:Many calls to Symantec support (after trying to connect for about 8 business days...) finally led to the comment that "we have to do it this way", and "using the DSFR writer is much, much slower", with the only reasoning being that Microsoft said so. See also http://seer.entsupport.symantec.com/docs/281856.htm There are no notes from Symantec about the implications of not using Hotfixes 29 & 31 on a DFSR server, nor the implications of backups run with a stopped "DFS Replication" service. Associated ArticlesThere is a real-world hint at Backing up DFS data. Last update : 03-07-2007 10:03
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