> Should be safe to skip the defrag. Layout on the virtual disk is probably > only loosely related to the layout of the zvol in the pool which is much more > about when the blocks were written, not where.
I’m just trying it out on a burner KVM zone at the moment, which I’ve purposely fragmented (the NTFS filesystem). Looks good so far. > Be aware that while you can clean up the current state of a zvol, if you > don't delete old snapshots, you're not actually getting your storage back. We keep the snapshots on the CN for 24 hours, so any benefits would have a ~24 hour latency, I understand. This isn’t really to free space up for use by something else, but rather to allow ZFS as much of the pool to work with as possible for the sake of performance. Thanks for the link, that’s a useful tool! Favourited :) > On 18 Jan 2017, at 16:33, Nahum Shalman <[email protected]> wrote: > > On Wed, Jan 18, 2017 at 11:02 AM, Adam Richmond-Gordon > <[email protected] <mailto:[email protected]>> wrote: > I am assuming you skip the defrag section of this, or will sdelete only zero > out the last contiguous block of “free” space? > > Should be safe to skip the defrag. Layout on the virtual disk is probably > only loosely related to the layout of the zvol in the pool which is much more > about when the blocks were written, not where. > > I only ask as we snapshot our KVM zones frequently, so any kind of defrag > would probably fill the zpool pretty quickly! > > Be aware that while you can clean up the current state of a zvol, if you > don't delete old snapshots, you're not actually getting your storage back. > Take a look at "usedsnap" on the zvol to get a sense of how much your > snapshots are costing you, and look at the "used" on each snapshot to see how > much each is uniquely saving. > I did a very short writeup about how to figure out how much is currently > being held by more than one snapshot here: > https://blog.shalman.org/used-space-hidden-in-snapshots/ > <https://blog.shalman.org/used-space-hidden-in-snapshots/> > > -Nahum > smartos-discuss | Archives > <https://www.listbox.com/member/archive/184463/=now> > <https://www.listbox.com/member/archive/rss/184463/28443474-1732e24d> | > Modify <https://www.listbox.com/member/?&;> Your Subscription > <http://www.listbox.com/> ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
