Comprehensive data protection for all workloads
Post Reply
cparker4486
Expert
Posts: 231
Liked: 18 times
Joined: Dec 07, 2009 5:09 pm
Full Name: Chris
Contact:

Do backups create dirty blocks on SAN?

Post by cparker4486 »

Hello,

The Snapshot Reserve Space on my EqualLogic SAN is being used up much more quickly than I would expect it to be and I wonder if this is due to Veeam making the virtual machine file blocks dirty.

I'm not talking about the vbk/vrb files that Veeam generates I'm talking about the virtual machine files themselves.
-- Chris
Gostev
Chief Product Officer
Posts: 31748
Liked: 7251 times
Joined: Jan 01, 2006 1:01 am
Location: Baar, Switzerland
Contact:

Re: Do backups create dirty blocks on SAN?

Post by Gostev »

Hi Chris, no - our product is read-only as it comes to pulling VM snapshot data from the storage during backup. Thanks.
tsightler
VP, Product Management
Posts: 6029
Liked: 2856 times
Joined: Jun 05, 2009 12:57 pm
Full Name: Tom Sightler
Contact:

Re: Do backups create dirty blocks on SAN?

Post by tsightler »

Equallogic snapshots eat space like a bear coming out of hibernation because, unless they've changed something in recent code versions, they use a 16MB block size. That means a single 4K block changed on a filesystem will cause a 16MB stripe copy for the snapshot. Just do a Google search about it and you'll get plenty of hits, here's just one example:

http://communities.vmware.com/message/1712215

However, if you are taking snapshots of the VMFS volumes then of course Veeam creating VMware snapshots will cause some additional growth as well because, while the snapshots are open, writes have to go into new files which reside on additional areas of the VMFS volume rather than back to the original VMDK location. But generally, snapshot growth on Equallogic is a problem whether you're using Veeam or not.
Post Reply

Who is online

Users browsing this forum: cgsm, denispirvulescu, Google [Bot] and 134 guests