VCB mounting question

[beckhamk]

I would like to verify what vmware means exactly when the VCB documentation says that a windows volume is mounted on the proxy server for backup.

Does this mean:

A) the vm's volume being backed up is setup kind like a mapped drive (unc shared) that the backup proxy server backs up?

or

B) the vm's entire volume is copied to the drive on backup proxy server. Then the backup is ran locally against the proxy's own disk copies of the vm's files?

[velinov · Accepted solution]

(B) is the way it works:

As you thought the vm's entire volume gets snapshoted and then is copied to the drive on backup proxy server. Then the backup (Backup Exec for example) is ran locally against the proxy's own disk copies of the vm's files... as simple as that...

[beckhamk]

wow - that doesnt make alot of sense. Why would all of that data get copied onto the backup proxy only to be backedup again?! I really thought this worked like option A). So what happens if you do not have enough disk space on the proxy server for the vm drive image to be copied?

[kix1979]

The file system CAN be mounted as a remote drive for backup. The VMDK files can NOT be mounted and must be exported to the local disk before being sent to tape as there is no NDMP support.

[depping]

kix is right, velinov half.

with VCB you have 2 options. File level and fullvm level backups:

1) file-level -> vcb mounts the vmdk on the proxy host to a directory, for instance c:\mnt. you will see a directory structure beneath it with the name of the VM and a directory for every disk. with a backup agent you can backup specific files of the VM

2) full-vm -> when you use fullvm, the complete vm gets dumped. or better said the vmdk and the files necessary to start the VM.

[velinov]

I agree that there are two options as you pointed out, For me the only useful option is the one that dumps the VMDK on the proxy, the file-level backup can actually be done by any backup software out there.

[beckhamk]

So just to be clear when the vmdk file is mounted/dumped as a directory structure on the backup proxy server, we have to have plenty of drive space for that mount to be dumped correct?

IE: if we only have a 36gb drive and the vmdk file we want to mount is 50gb in size, then we can not performan a file level backup is that correct?

What happens with full vm images? do we have to have enough diskspace for the entire vm file to be temp stored for the backup program to backup the data?

[kix1979]

So just to be clear when the vmdk file is

mounted/dumped as a directory structure on the backup

proxy server, we have to have plenty of drive space

for that mount to be dumped correct?

If you are mounting the file structure, you require NO space on the backup proxy. Only when you are doing an image level export do you need to have space.

IE: if we only have a 36gb drive and the vmdk file

we want to mount is 50gb in size, then we can not

performan a file level backup is that correct?

What happens with full vm images? do we have to have

enough diskspace for the entire vm file to be temp

stored for the backup program to backup the data?

Correct, you need to have enough free space for your largest VMs and then some, because odds are you will be streaming multiple VMs to be backed up at a time.

Kix

[GBromage]

IE: if we only have a 36gb drive and the vmdk file

we want to mount is 50gb in size, then we can not

performan a file level backup is that correct?

That's true, yes. There is an option to compress the disk as it mounts. So, if you have a 50Gb VMDK and only, say, 20Gb of it was used, then you might be able to mount it on a 36Gb drive.

Used[/b], in this case, is defined as the number of disk pages in the raw VDMK file that aren't made up entirely of zeroes.

If the data on the virtual drive is reasonably dynamic, you can improve your compression by running a utility like SDELETE across it to zero out the unused space.

If you search the forums here for the word SDELETE you'll come across some excellent discussions about it.

Greg

[depping]

sdelete works like a charm, saved me 100gb on a total of 550 at the last VCB project i did.