Business Copy EVA and Windows 2003

[Joseph Salzer_5]

I am looking to see if someone can clarify whether or not you can present/mount a Snapshot
( Not snapclone) to a windows host where the parent vdisk is currently presented/mounted.

I know this is possible in HP-UX because I do it all the time. I seem to remember that Windows 2003, does not support mounting the Snapshot on the same host while the parent vdisk is mounted. In other words, the snapshot can only be mounted on a different host.

If it is possible to mount the snapshot on the same host as the parent, what is the proper way to do so? I have tried several ways, but windows always detects the snap as a "foreign disk" evan after importing it.

Thanks,
Joseph

[Uwe Zessin · Accepted solution]

It is still not possible and it does not matter if you use a snapshot or a snapclone. Both appear as 'identical copies' of the parent virtal disk including the disk signature.

[Joseph Salzer_5]

Thanks Uwe, that pretty much answers my question.

The only reason I specifed Snapshot and not Snapclone is because once the SnapClone process is complete it becomes its own entity indenpendent of the parent copy. This would allow you to mount/present the snapclone on the same host as the parent. Or am I wrong and Windows won't even allow you do this?

Thanks again for your input.

Joseph

[Uwe Zessin]

Joseph,

I have just checked and at least in CV-EVA (don't have a BC-EVA setup in the lab right now) I can present a snapshot to the same host as the parent disk. Not surprising as you already wrote that one can do that with HP-UX, although one must be careful, because you have to deal with duplicate identifiers of PVs and VGs as well.

From a logical view, the host does not see a difference between a snapshot and a snapclone - both are 'point of time copies'.

[L. B. Andersen]

You should ask HPQ for some kind of EVA / VSS (volume shadow copy)interface.

This should enable the requested functionality, as long as it is W2K3.

rgds


lars

[Joseph Salzer_5]

Uwe, Are you able to use the snapshot after presenting it to the host in your environment? If so, how are you accoplishing this?

Yes, under HP-UX I do it all the time and it works great, assuming you do it properly (vgchgid, vgimport, etc. etc.)

L.B. If I am not mistaken, the installation of the BC Host Agent on a system where Volume Shadow Copy Services are used is not supported. I've checked the BC 2.3 Admin guide and it says the following: "BC does not support installing BC host agent software on Windows Server 2003 hosts using Volume Shadow Copy Services, because of interoperability issues"

[Uwe Zessin]

Hello Joseph,

I am not running BC in a production environment, but I just did a short test:

- two servers running Windows 2000
- both have a single virtual disk mapped
- create a snapshot from one VD and present it to the other server using CV-EVA
- on the other server, just do a 'rescan disks' and the snapshot pops up like a normal disk
- of course, I can put new data on the snapshot because it is writeable by default (else, the NTFS cannot be mounted -- tried it and the system 'acts strange')
- yes, I know that the data is gone once I delete the snapshot ;-)


I haven't tried presenting the snapshot to the same server - I did this some years ago and it completely screwed up the system (it was the last action during a storage training and I wanted to see what it looks like).

[Vladimir Vlcek]

Hello,

I think that same disk signatures on parent and coppied disk avoids correct utilization of such configuration. Even if you successfully connect copied disk problems may start a little bit later when you try to work with it. If it is possible connect cloned disk to different system first and change signature for example with dumpcfg utility from resource kit (dumpcfg -S), than you can present it back to the original server.

Vladimir