Data Backup and Recovery

SnapDrive cannot create SnapShot on LUN mapped as RAW volume


Hello, all!

As stated in the title, I've setup a 54Mb test LUN to map to a Windows 2003 platform as a RAW volume/device. I did that from MMC (initialized, no drive letter assigned, not formated) as SnapDrive usually formats it to NTFS by default...

Anway, I wanted to see whether SnapDrive 5.0.1 could still perform SnapShot creation on it, as it could be used as a storage option for Oracle RAC, but I got an error saying:

Unable to create snapshot of a virtual disk.

Failure in checking policies.

Error: Snapshot creation of virtual disks cannot occur at this time. This situation can be caused by the virtual disk being offline, ot this disk has a VLD type, or not owned by this computer.

Here's a screenshot, click on it to see it in full:

I haven't much experience with this type of management. Any thoughts on how to fix or work around this issue?





How was the LUN created? Was it created and managed by SnapDrive?

I can create a snapshot on a LUN without drive letter. But the LUN was created by SnapDrive and is managed by SD. Therefore, it was NTFS formatted. By the way, I'm using SDW v6.0.

Hope that helps,



Hello Wei,

Like i said, I didn't use SnapDrive because in Widnows it always formats LUNs with NTFS.

I've created the LUN manually with FilerView and connected it through MMC console, so that it would remain RAW (unformated). I could assign a drive letter to it but there was no need, SnapDrive recognized it...

It just won't take a snapshot and I don't see why not. All it does is temporarily place the disk offline, flush the system's memory buffers and takes a snapshot. It shouldn't matter much what type of data is being written at the time, or not.



If I understand correctly, you are trying to snapshot an unformatted LUN via SnapDrive.

It's not doable in my opinion, as SnapDrive is responsible for putting file system in a consistent state before snapshot is taken. As there is no file system on the LUN, there is no way to flush anything to disk.

Why not snapshot the volume on the filer side? (well, obvious question is - why take a snapshot if there is no data in the LUN? or is it?)



There should be data on the LUN, as Oracle RAC would use it for read/write - but that's a job for Oracle DBA. All I'm supposed to do is provide the raw volumes.

And yes, from that perspective, I guess SnapDrive cannot be used for creating snapshots. I suppose they'll have to use a script to bring the database down, followed by a snapshot on filer side and than back again.


There is SnapManager for Oracle on Windows product, but I believe it won't work with raw LUNs, as it relies on SnapDrive, so we are back to square 1.

Oracle in general is well scriptable (at least on UNIX ;-), so I guess a DBA can even accomplish hot backups (by putting DB in a hot-backup mode before triggering snapshot on the filer side).



I guess that'll have to do. 🙂 Thanx, Radek!