I am experienceing very slow backups of DFS
Incrementals are backing up around 870000 files and 45Gb or data, but are taking around 5+ hrs, reported speed at the end of the backup is 2395KB/sec, all other backups run with out issue and complete in expected times. i have checked the logs and can see the following
Feb 16, 2022 1:10:23 AM - Info bptm (pid=960) waited for full buffer 86594 times, delayed 1189821 times
Feb 16, 2022 1:10:24 AM - Info bptm (pid=960) EXITING with status 0 <----------
Feb 16, 2022 1:10:24 AM - Info bpbrm (pid=5880) validating image for client
Feb 16, 2022 1:10:26 AM - Info bpbkar32 (pid=9644) done. status: 1: the requested operation was partially successful
Feb 16, 2022 1:10:26 AM - end writing; write time: 5:09:56
Reading online i can see that this could be pointing to a client side issue, but so far have not been able to pin down the root cause, the DFS is on a VM which has RDM, i have checked with the SAN performance and all is acceptable
Would anyone have any pointers as to what could be causing this issue.
Unfortunately DFS backups are painful. They are the classic case where Microsoft created a product and the day before releasing someone said, "Hey, how do we back this thing up ?"
Since the backup jobs go through the registry there is very little you can do directly to speed them up - they tend to have all of the pain points of a Fileserver backup with tons of small files, slow directory traverse, and slow overall throughput.
While you could look into tuning those buffer settings for size & number, unless you have a dedicated Media Server for just this one client you may speed this one up and slow a different unrelated backup job down.
My recommendation would be that if your job is only taking 5 hours during an 8 hour overnight window & completing successfully, I would call it a win and leave it alone.
If you really want to sink additional time into the issue here's a few technotes on configuring the policy for Accelerator but I would be really hesitant about implementations that require an Admin to notify you when they add/remove replication folders.
How to configure DFSR backups to use Accelerator with NetBackup versions
Incremental backups of DFSR data using Accelerator back up too many files
Best of luck!
Great post from @jnardello
And from the deep pits of my mind I recall that :
And for slow backup, do not use tape. Send backup to disk first, and then stage to tape.