Slow incremental fileserver backups - how to troubleshoot?

[JaySt]

I'm seeing very slow incremental fileserver backups using VAW. Fileserver has a data drive of 6TB, which took 17 hours to complete during a full backup.
Incremental backup run for ~30 hours, have a data read amount close to 3TB but a transfered data amount of < 200GB.

Any tips on troubleshooting this one? i'm not sure why VAW is scanning 3TB of data every incremental job and also why this backup is only transfering <200GB eventually.

[Dima P.]

Hi JaySt,

What backup mode are you using? Do you have throttling option enabled?

[JaySt]

i'm using the "entire computer" mode. No throttling enabled.

[vClintWyckoff]

Jay-
VAW has to determine which files have changed since the previous backup to create the VIB file. To do this VAW checks the files in the MFT to see if the file has changed since the previous backup, if the file has changed then its included within the VIB. IMO, and in your scenario it makes sense that the full backup is quicker - its straightforward, backup everything - whereas with the incremental needs to determine what's changed versus what's not and 6TB on a file server is a lot of files.

It sounds like this is a physical file server, what are the specs of the server and backup target? Also, to clarify you're running the GA version of VAW 2.0.0.700?

[JaySt]

But MFT checks are mostly quite fast right? To me, the weird thing is the job logs show a data read amount of 3TB (half the volume) and less than 200GB is actually transferred. If some kind of daily process would touch 3TB of files (which causes them to be read if i understand correctly?), how can the actual VIB be so small after in that case? Is VAW scanning all changed files (as marked changed in the MFT by who-knows-what) and looks for blocklevel changes maybe? (i'm not fully aware of the scheduled tasks that take place on the fileserver and what they do, i did not setup this fileserver myself, so i cannot rule out such a process "interferes" with the backup just yet)

It's a virtual machine on a Hyper-V host, having a in-guest iSCSI connection to the data volumes running on the SAN. 1Gbit iSCSI. 16GB RAM VM, running 2vCPU's
yes i'm using the latest VAW build currently available.

[vClintWyckoff]

Probably the best course of action would be to contact support and then come back with the case number so the devs can track.

[JaySt]

Yeah i'll create a case soon. will post back when i know more.