Space required for replication

[egroeg]

Dear forum.

Is there anyway to determine what space is required on the native storage lun disk to conduct a successful replication.

At present, my SAN is full, and I have a 2TB data disk on one of my VMWare VMs which the fat VMDK that consumes 99.9% of the disk.

Problem is that when I try to replicate, there is no space on the SAN LUN to create the snapshot and move this over.

Before I start jiggling LUN space around, can anyone tell me how much sparce space you need on the LUN to allow a successful replication for a 2TB vmdk?

Regards
George.

[Alexey D.]

Hello George,

Typically snapshot size could be 10-20% of size of a disk, but this number highly depends on VM's activity. So, it's hard to be precise with these estimations.

[Gostev]

Yes, it is best to make sure you have at least 10% of free disk space to be on a safe side. Snapshot growth depends VM disk activity and time backup job runs (which in turn depends on the amount of changes the job needs to process during the given run). Full backup of very large server may take hours or even days when backing up over slow connection, so if your server is very chatty, snapshot can grow big (10-20%). Incremental runs are generally much faster, so if you "survive" incremental run, you typically do not need to worry any longer, as those take 10-15 mins or less for average server, so snapshot does not stay too long.

[egroeg]

Ok - thanks Gostev.

One more quick question.

My windows guest fat VMDK is 2TB. If I change the size of my LUN on the iSCSI San to be say 2.3TB, but leave the Windows VMDK at 2.0 TB, will this affect VMWare on the disk?

I presume not as all I am doing is increasing the size of the LUN from the iSCSI SAN web gui....

Thanks in advance.

[Vitaliy S.]

will this affect VMWare on the disk?

I'm not sure I follow you, but your VM shouldn't be affected by this change (if you mean it).

[egroeg]

Yes Vitaly, that is what I mean.

I just wanted to be certain that the expansion of my LUN at the SAN level wouldn't affect the VMWare.