VM Snapshots: Will my RDM be affected?

[mgaccess]

Hi, I have a 20G vmdk for my OS (linux) and a couple of large physical RDM disks (data only) presented to the guest via iSCSI and mounted in /mnt. I need to apply some OS and Application updates on the 20G vmdk and would like to snap it before I do so. I'm a bit nervous because I am not sure how the RDM disks will react when I take a snapshot and when I delete the snapshot. Will the snap just ignore the RDM disks? Thank you.

Oh, I'm running ESXi 4.0

[geddam]

Since OS disk is a vmdk file, you will be able to take a snapshot and apply updates as required and then commit as well. They are physically isolated disks although they are logically linked by single OS. Snapshot requires a queiscing of filesystem at OS level. So there should be no issues.

Thanks,,

Ramesh. Geddam,

VCP 3&4, MCTS(Hyper-V), SNIA SCP.

Please award points, if helpful

http://communities.vmware.com/blogs/rameshgeddam

[AntonVZhbankov]

If you have RDMs in Virtual mode then snapshot process will treat RDM disks as usual vmdk, with deltas etc.

---

MCSA, MCTS, VCP, VMware vExpert '2009

http://blog.vadmin.ru

[geddam]

I believe the question here is for OS disk which is VMDK, but not data drive which is an RDM, So, creating snap for OS disk will not affect RDM...it doesn;t matter whether RDM is in physical compatibility mode or virtual compatibility mode. Correct me if I am wrong Anton!

Thanks,,

Ramesh. Geddam,

VCP 3&4, MCTS(Hyper-V), SNIA SCP.

Please award points, if helpful

http://communities.vmware.com/blogs/rameshgeddam

[AntonVZhbankov]

Snapshot is created for entire VM (i.e. all disks), you can not choose which disks include to snapshot.

---

MCSA, MCTS, VCP, VMware vExpert '2009

http://blog.vadmin.ru

[JimKnopf99]

Hi,

which VMware License do you have.

I would prefer to install the VDR.

There you can Backup your VM and you can easy manage which partition (vmdk) you backup.

Then you are safe. There is a possiblity to check the Backup as well.

Frank

[geddam]

Agreed! But this is possible. This is what I have tried and works well for me.

As this is a OS disk....

1. Detach RDM;s from VM.

2. Take a snapshot for OS disk.

3. Apply the required changes

4. Delete or revert snapshot and re-attach RDMs

Hope this helps

Thanks,,

Ramesh. Geddam,

VCP 3&4, MCTS(Hyper-V), SNIA SCP.

Please award points, if helpful

http://communities.vmware.com/blogs/rameshgeddam

[a_p_]

I read your post a couple of times and I'm not sure on how you actually access the LUNs.

As AntonVZhbankov mentioned, all virtual disks (vmdk) as well as all RDMs running in virtual compatibility (vRDM) mode are affected by a snapshot. RDMs in physical compatibility mode (pRDM) are mot affected by snapshots.

Now, when talking about RDM's, this is when you present the LUNs to the ESX(i) host(s) and assign them as virtual disks to the VM using edit settings.

However, what confused me is:

... RDM disks (data only) presented to the guest via iSCSI ...

If that means you use a software iSCSI initiator within your VM to access the LUNs directly, then they will also not be snapshotted.

André

[AntonVZhbankov]

>If that means you use a software iSCSI initiator within your VM to access the LUNs directly, then they will also not be snapshotted.

In this case these LUNs are not actually RDM :smileyhappy:

---

MCSA, MCTS Hyper-V, VCP 3/4, VMware vExpert '2009

http://blog.vadmin.ru

[mgaccess]

Thank you all for your replies. Conclusion: I should be able to take a snapshot of the vmdk without affecting any of the RDM disks.

@a.p sorry for the confusion. What you said is exactly what I am doing... "present LUNs to the ESX(i) host(s) and assign them as virtual disks to the VM

using edit settings"

I'm not familar with virtual RDM's - kinda sound like an oxymoron :smileyhappy: