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I currently have a FreeNAS server with three 500GB drives setup in a RAIDZ array. It's currently used to serve an iSCSI extent to my Citrix XenServer Pool. When I created the extent I gave it the entire pool so it's size is reported as 913GB but I'm only using like 20GB.

I've just been given 4 SSDs to replace the 500GB drives and I want to know what's the easiest way how to backup the VMs and restore them on a new RAIDZ array that I'm going to create. My intention is to use the same physical server, but I don't have enough SATA ports to plug them all in.

So my original idea was to backup the extent file that was created, but it's size is reported at 913GB! I'm really at a loss considering all of the options available to me, what is going to be the easiest way to backup and migrate this data?

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Well you can't shrink the pool unfortunately so unless you can reduce the size of the extent down to DATA+a little then you will simply export each VM and then import to the new (smaller) SSD pool. – Joshua D'Alton Mar 18 '11 at 4:36
up vote 0 down vote accepted

Iam not sure I totally understand you question.

But i'll try to answer anyway,

dont backup the iscsi lun it self - backup the vms

or even better - backup the vms to nfs/ext3 repository ( it will use thin provision )

check out this great script to backup vms:

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