Saturday 1 June 2013

DPM and Manual Replicas. Not quite as intuitive as the rest of Data Protection Manager!

We don't tend to post here very often anymore, mostly because it's rare there's anything much to say since we moved away from Backup Exec (which seems to be just as bad as ever when I recently evaluated it to see if it had improved).

Data Protection Manager does, on the whole do a damn good job of making backups work reliably. There are some annoying quirks and on the whole when it does have a problem of some sort it tends to be communication with server issues, and the error numbers, messages and explanations are pretty hopeless in many cases, which does take the shine off an otherwise decent product.

But one area that we have recently been exploring in more depth is the "Manual Replica" feature. Traditionally we've not really had any need to get initial replicas via anything but the LAN/WAN links already in place, but more recently we had a few scenarios where it sounded like it could be a winner.

The process is pretty much undocumented as far as TechNet goes - there is a vague explanation but it doesn't cover several obvious and common scenarios whatsoever.

The basic principle is that you literally "copy" the source drives files to another media - like a removable hard disc, then copy them onto the DPM server. 

Sounds simple right?

The first stage is - assuming you've got a couple of good tools that let you grab "in use" files or get via some VSS handiness, and can add an NTFS formatted drive etc. In practice it is the second part - getting it into DPM - that far more convoluted as you have to know the replica path, you have to mount it so you can access it to copy files and then you can copy the files.

The hassle lies in having to get the replica path from DPM's admin console (easy), copying that to clipboard and into notepad or similar (easy), extracting the volume ID (easy as long as you know which bit is the volume ID), and then finding the actual volume ID windows has via mountvol (time consuming to do when you have a lot of volumes), and not that easy. Finally you need to mount that volume so you can access it, browse to the "Full" folder and copy the files (only easy once you know how).

All of this would be relatively simple if the documentation was decent, but it isn't.

What makes it more bizarre is that the process of getting the IDs and mounting volumes is something that could be done within the UI if they wanted pretty easily, or at least via some DPM powershell.

Since this wasn't the case (and isn't as of the latest build), one of my colleagues and I knocked up a little script to make the last part a bit neater - essentially we feed a script the DPM volume string, and the drive letter we want to mount as, and the script queries the system volumes, finds the matching one and mounts it. Voila!.

Copy the files, then run a consistency check on the manual replica, which will then complete the job and let ongoing backups happen.

So we're done now right? Well not quite.

All of the above assumes you're creating a manual replica of a file storage volume (eg a typical "drive"). There doesn't appear to be any documentation on the TechNet site for any release of DPM that explains how you create manual replicas for resources like SQL Server, Exchange - it suggests you can, and you can make those resources go into "manual replica creation pending" but it does not make it at all clear how you actually achieve this.

So my simple request to Microsoft is PLEASE provide better documentation in this area, and perhaps throw in a couple scripts to simplify the process so we can just "get on with it" - as a general rule the Server 2012 and DPM 2012 releases do exactly that so it'd be good to see that last bit work too.