EVA4100 and VMware (Snapcloning question)

[Digex]

Anyone running Vmware ESX 3.5 with a lun on a EVA4100? I was wondering if you could use snapcloning to backup the entire lun to another disk group or tape and what is required to do so like shutdown all virtual machines etc?

[Uwe Zessin]

Certainly you can snap a VMFS - for the EVA it is a collection of data blocks. The EVA will not care if the clone is directed to the same or another disk group.

Unfortunately, there is no synchronization between the activity of the VMs and the snap, so all data is crash-consistent unless you do shutdown all VMs first.

How to proceed from there?
You do need an ESX server to mount the VMFS and access any files, but I am sure you know that. Now, if you present the clone to the original server, it will most likely not work:

- you cannot present it at the original LUN address

- if you present a VMFS on a different LUN address, ESX detects this and refuses to mount, to prevent data corruption due to identical file system signatures.

You can make the data available if you set the LVM.EnableResignature system parameter and do a rescan.

WARNING! WARNING! WARNING! WARNING! WARNING!

Make sure that the LVM.DisallowSnapshotLUN parameter is not active when you are operating with clones!!!


Have you thought about using VCB? The current version does have a VSS hardware provider for Windows VMs.

[Digex]

Im looking into VCB now and need to find some way of doing backups of vm's without spending too much extra. I like Veeam Backup but the extra cost is not what we want to spend right now. What ways can you use VCB? Does it backup to tape or to another datastore?

[Uwe Zessin]

You can use VCB inside the service console to take an 'image' backup of the VMDK files and the remaining file which make up the VM. The result can be stored on a VMFS datastore or an ext3 filesystem. (Maybe on an NFS-mount, too -- a CIFS-mount is not recommended, because the SC can hang).

Another way is to map the VMFS datastores to a Windows 'proxy' server. From here you can, too, take an 'image' backup similar to the one in the service console and store it on a (local) NTFS.

Another possibility is to do a 'file backup' of Windows VMs. The proxy can map to the VMDKs of a VM and mount these filesystems to a local mountpoint, e.g.
C:\mnt\vm-win1\letters\c\...
C:\mnt\vm-win1\letters\d\...

There are enabler modules for a number of backup packages including HP dataprotector to do the pre- and post-exec stuff (take a VM snapshot, mount the volume / unmount the volume, delete the VM snapshot).