none
why no BMR on workgroup machine? RRS feed

  • Question

  • Bare Metal Restore (BMR) option is not supported by DPM on workgroup machines as detailed here (https://technet.microsoft.com/en-us/library/hh757801.aspx).  Anyone knows what the technical limitation is, just trying to understand the reason why the option is missing.  
    Friday, June 12, 2015 6:43 PM

Answers

  • Interesting question! I'll point out firstly that I don't know if this is the reason, and if someone does know for certain I'd be interested in knowing as well, but I suspect it's due to the way that BMR backups are done compared to other backups controlled via DPM.

    For instance, with a System State backup the data is backed up locally on the server via WSB, and then once completed it's transferred to the DPM server. BMR however handles it slightly differently. Rather than backup the data locally, DPM instructs BMR to backup the data direct to the DPM server. There's a good writeup on the process here http://blogs.technet.com/b/dpm/archive/2013/05/16/dpm-and-system-state-backup-explained.aspx but the important bit is :

    "How does this differ from a BMR backup? Well, with BMR (which inherently captures a system state as part of the process), the backup job will be done directly to a share on the DPM server. What happens is that the DPM server shares out the replica volume for that BMR backup and when it calls WSB, it just tells it to not use the drive with the most free space, but instead use the share that it has created for this job."

    So I suspect the issue is that with a non-BMR backup DPM simply needs the required permissions to connect and access the protected server to do the backup. With a BMR backup however the protected server also needs permissions and access direct to the DPM server to allow it to perform the backup, and while the former is easy to allow in a Workgroup setup, it's harder to securely allow that for the latter.

    So in short I suspect the reason is that the supported DPM workgroup backups only really need one-way authentication, but BMR backups require two-way authentication and they haven't included support for that (or perhaps more likely there's simply no way to instruct WSB in how to do that authentication with the current WSB build).

    Friday, June 12, 2015 8:41 PM