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Re: Slow performance on file system backup even to disk

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I didn't want to go into too much detail unless this was something you wanted to pursue outside of the normal case creation process

 

1. You said about running Disk Agent (VBDA) in stand-alone mode - how do i do this?

I would probably need to see a session report of a slow backup (hopefully with the option 'Display Statistical Info' enabled) and the OS-type and version of what you are backing up.  From this, I would have you run, from the command line of the affected erver:

 

   vbda -vol [volume] -trees [what is being backed up] --out [nul output] -profile

 

So, for example, to check the backup of the \Users folder on the D: partition  on a Windows system

 

  vbda -vol /D -trees /Users -out nul -profile

 

This would have the effect of not accessing the IDB or any device

 

2. then try backing up the same sample to a local 'nul' device to see if it is a network issue - How do i do this?

First, this has to be an apples-to-apples comparison, which means you are going to test against the same set of files used in test #1.  In your 'global' file, find this line

 

# FileMediumCapacity=MaxSizeInMBytes

 

Make a copy of thsi line on one of the lines, uncomment it and remove teh 'space that follows, and set the value somewhat over the amount you are testing with.  So, for example, if you are testing with 750MB

 

FileMediumCapacity=800

# FileMediumCapacity=MaxSizeInMBytes

 

Save the file, stop and restart DP

 

ON the Disk Agent you are testing with, create a 'file-type standalone' device in the Drive tab use 'nul' (Windows) or /dev/null (UNIX) as the destination file

 

Create a backup specification, with the option 'Display Statistical Info' enabled, and using the 'nul' device as a destination.  Run your backup, in the session report, compare the Statistics against what you got from backing up to VBDA.  This will write to the IDB, but will not go across the network, and will not use a Backup Device

 

Change the test backup specification to use a Normal writer, run the backup, and, again, display statistical Info, and compare it to the first 2 tests

 

4. Distributed File Media Format (DFMF) is only used in a very limited setting, and it usually causes more trouble that it si worth (for exampe, you can't delete media), and I recommend against using this option - So if you don't use DFMF what mode do you suggest? do you mean we should be using a VTL?

No, DFMF is a checkbox.  YOu either select it to use DFMF, or don't select it, so as not to use DFMF

DFMF is required when doing Advanced Incremental Backups with the intention on converting them to Full Backups. Very few people use this, those who do preferring to create Synthetic Full Backps method

 

If you want to send me a session report, but not expose it to the community, you can send it to me directly at

 

    r.clark@hp.com


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