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Basics – no_striped_recover

Posted by Preston on 2009-04-03

With the introduction of the advanced file type (adv_file) device in NetWorker, changes were made to support striped recoveries. This is a recovery where if all the savesets required to facilitate a recovery are online, NetWorker commences parallel reads, speeding up the process considerably. This applies both for file and tape based devices. Both in theory and in practice, it usually works great, but there is at least one key exception I’m aware of.

For many releases of NetWorker, striped recovery can fail on Linux if more media needs to be mounted than there are devices to read from. For instance, if you have a recovery that needs to read data from 4 tapes, but you only have 3 tape drives available, in many instances of NetWorker on Linux you’ll get the situation where NetWorker will mount 2 or 3 of the tapes, but then appear to just “hang” the recovery before it starts.

Thankfully, there’s actually a relatively easy solution.

Within the /nsr/debug directory, you can create the file:

no_striped_recover

At that point, NetWorker will revert to the traditional recovery style – reading in sequence from each volume, starting at the oldest saveset required and coming forward to the newest saveset required, pulling the requisite chunks of data from each saveset.

If you’re wondering, the content of the file is irrelevant; thus, you can simply:

# touch /nsr/debug/no_striped_recover

If the recovery is actually running, you’ll need to cancel it and run it again – note that you do not have to restart the NetWorker server though.

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