Re: ZFS reservations for type=volume
- Reply: Michael Jung : "RE: ZFS reservations for type=volume"
- In reply to: Alan Somers : "Re: ZFS reservations for type=volume"
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Date: Thu, 21 Apr 2022 21:58:34 UTC
(My FBSD dev env isn't booted, but Linux and FBSD are the same in this regard...) # zpool list workspace NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT workspace 35.4T 12.9T 22.5T - - 3% 36% 1.00x DEGRADED - # zfs create workspace/testme # zfs list workspace workspace/testme NAME USED AVAIL REFER MOUNTPOINT workspace 13.0T 21.5T 48.9G /workspace workspace/testme 96K 21.5T 96K /workspace/testme # df -h /workspace/testme /workspace/ Filesystem Size Used Avail Use% Mounted on workspace/testme 22T 128K 22T 1% /workspace/testme workspace 22T 49G 22T 1% /workspace # zfs set reservation=1T workspace/testme # zpool list workspace NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT workspace 35.4T 12.9T 22.5T - - 3% 36% 1.00x DEGRADED - # zfs list workspace NAME USED AVAIL REFER MOUNTPOINT workspace 14.0T 20.5T 48.9G /workspace workspace/testme 96K 21.5T 96K /workspace/testme # df -h /workspace/testme /workspace/ Filesystem Size Used Avail Use% Mounted on workspace/testme 22T 128K 22T 1% /workspace/testme workspace 21T 49G 21T 1% /workspace # That is, AIUI, reservation counts against the USED/AVAIL/FREE shown by "zfs list" or "df" of everything not the reservation-holder , not against the "ALLOC" shown by zpool list...unless it's actually allocated, of course. - Rich On Thu, Apr 21, 2022 at 5:46 PM Alan Somers <asomers@freebsd.org> wrote: > Isn't 1.52T the "AVAIL" value, and 24.6T is the "USED"? > > On Thu, Apr 21, 2022 at 2:56 PM Michael Jung > <mikej@paymentallianceintl.com> wrote: > > > > Ok that makes sense... so even though running ZFS since 9.x I'll ask the > newbie question.. > > > > If it contributes to the parents "used" value why is not reflected here > in "USED" or in "AVAIL"? > > > > I would expect USED to be my reservation amount of 15.6T + whatever > space was > > being used by other things on the pool. "USED" still sits at 1.52T. > > > > NAME TYPE USED AVAIL RATIO COMPRESS RESERV REFRESERV VOLSIZE > > raid-5400-1 24.6T 1.52T 23.1T - - 2% 6% 1.00x ONLINE > > > > Thanks again. > > > > -----Original Message----- > > From: Alan Somers [mailto:asomers@freebsd.org] > > Sent: Thursday, April 21, 2022 4:40 PM > > To: Michael Jung <mikej@paymentallianceintl.com> > > Cc: freebsd-fs <freebsd-fs@freebsd.org> > > Subject: Re: ZFS reservations for type=volume > > > > A dataset's reservation is local. It doesn't contribute to its parent's > reservation. Otherwise, you wouldn't be able to separately set a > reservation on the parent. But it _does_ contribute to the parent's "used" > value. In that way, you're prevented from reserving too much data on the > parent's children. > > -Alan > > > > On Thu, Apr 21, 2022 at 2:28 PM Michael Jung < > mikej@paymentallianceintl.com> wrote: > > > > > > I have a zfs block dataset raid-5400-1/esxi-store1 that I share as an > > > iscsi target and that works great. I have set a reservation > > > > > > on that block device equal to its size so that is not sparse and thus > > > while I could over provision guests on the provided LUN, > > > > > > the storage presented as the LUN capacity will always be available. At > least this is what I want to achieve. > > > > > > > > > > > > What I find strange is that the reservation does not seem to be > > > applied to the ZFS pool ‘raid-5400-1’. Do you really need > > > > > > to set your maximum reservation at the pool level, and then apply > > > reservations to all datasets on that volume? And if so > > > > > > I would assume you could never set reservations for datasets totaling > more than what was reserved for the pool ‘raid-5400-1’. > > > > > > > > > > > > I could build out a test environment and figure out constraints but > I’d really like to know the “how it is supposed to work” > > > > > > not the “how I find it to work”. > > > > > > > > > > > > Thanks in advance. > > > > > > > > > > > > FreeBSD 14.0-CURRENT #4 main-n253875-8e72f458c6d: > > > > > > > > > > > > (this is a raidz2 pool – not my draid pool) > > > > > > > > > > > > > > > > > > root@draid:/usr/src/contrib/bearssl # zfs list -o > > > name,type,used,avail,ratio,compression,reservation,refreservation,vols > > > ize raid-5400-1 > > > > > > NAME TYPE USED AVAIL RATIO COMPRESS RESERV REFRESERV VOLSIZE > > > > > > raid-5400-1 filesystem 18.0T 2.08T 1.36x on none none - <- no > reservation @pool > > > > > > root@draid:/usr/src/contrib/bearssl # > > > > > > > > > > > > root@draid:/usr/src/contrib/bearssl # zfs list -o > > > name,type,used,avail,ratio,compression,reservation,refreservation,vols > > > ize raid-5400-1/esxi-store1 > > > > > > NAME TYPE USED AVAIL RATIO COMPRESS RESERV REFRESERV VOLSIZE > > > > > > raid-5400-1/esxi-store1 volume 16.9T 18.5T 1.78x zstd 15.6T 16.9T > 15.6T <- reservation @dataset > > > > > > > > > > > > root@draid:/usr/src/contrib/bearssl # zpool list > > > > > > NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT > > > > > > ccache 9.50G 9.10G 406M - - 88% 95% 1.00x ONLINE - > > > > > > raid-5400-1 24.6T 1.52T 23.1T - - 2% 6% 1.00x ONLINE - <- Free does > not reflect reservation @pool > > > > > > tank 18.5T 605G 17.9T - - 0% 3% 1.00x ONLINE - > > > > > > zfsroot 103G 33.3G 69.7G - - 31% 32% 1.00x ONLINE - > > > > > > root@draid:/usr/src/contrib/bearssl # > > > > > > > > > > > > > > > > > > CONFIDENTIALITY NOTE: This message is intended only for the use of the > > > individual or entity to whom it is addressed and may contain > > > information that is privileged, confidential, and exempt from > > > disclosure under applicable law. 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