On 01/22/13 16:02, Sašo Kiselkov wrote:
On 01/22/2013 05:00 PM, casper....@oracle.com wrote:
Some vendors call this (and thins like it) "Thin Provisioning", I'd say
it is more "accurate communication between 'disk' and filesystem" about
in use blocks.

In some cases, users of disks are charged by bytes in use; when not using
SCSI UNMAP, a set of disks used for a zpool will in the end be charged for
the whole reservation; this becomes costly when your standard usage is
much less than your peak usage.

Thin provisioning can now be used for zpools as long as the underlying
LUNs have support for SCSI UNMAP

Looks like an interesting technical solution to a political problem :D

There is also a technical problem too: because if you can't inform the backing store that you no longer need the blocks it can't free them either so they get stuck in snapshots unnecessarily.

Darren J Moffat
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