wbadmin.exe start backup -allcritical -quiet -backuptarget:\\server_name\bmrshare
I have to say for a purely Microsoft-based backup solution, backing up a purely Microsoft server, it is ridiculous that it can't calculate the BMR automatically and effectively. If an end-user can do it manually using a Microsoft tool, then a mature, premium Microsoft backup product should be able to. So if I have 100 servers to back up with BMR, Microsoft expects me to run 100 trial manual backups just to figure this out?????!
As I understand it, the issue is that DPM doesn't directly do the BMR backup, it basically calls wbadmin and uses that to perform the actual backup on the protected server. Therefore if wbadmin isn't able to determine the space required (without running a backup to another source first like above) then neither is DPM. Since the BMR backup excludes user files, wbadmin and DPM can't simply look at the amount of space used on C:\ to get a figure. It presumably needs to scan through all the files on there and determine which are system files and which are user files.
I would like clarification on the statement "make sure that the same amount of disk space or more have been allocated to the replica volume".
Our replica volumes are set to grow automatically and there is ample unallocated space in the storage pool. So why am I getting an insufficient disk space error when I know there is plenty of room for the BMR. Other articles have stated that the BMR doesn't get saved locally WSB (blogs.technet.com/.../troubleshooting-data-protection-manager-system-state-and-bare-metal-backup.aspx), so if that's the case why am I getting this error? Is there something in DPM that needs to be adjusted to manually increase the replica volume?
eroseland: DPM will only grow the volumes by 25% each time (see technet.microsoft.com/.../ff399717.aspx), so if that increase isn't enough to encompass the space requirements then you'll continue to get an error. Eg, if DPM has guessed that you'll need 10GB, but there's actually 50GB requiring backup, then it will fail due to insufficient disk space. If it grows automatically it will grown to 12.5GB, which still isn't enough and it'll fail. Then again it will grown, but now to 15.63GB, and again it will fail.
To avoid that you need to determine the required space for the volume and configure that accordingly, in those occasions where the estimate made by DPM turns out to be wrong.