Date: Thu, 21 Apr 2022 14:40:29 -0600 From: Alan Somers <asomers@freebsd.org> To: Michael Jung <mikej@paymentallianceintl.com> Cc: freebsd-fs <freebsd-fs@freebsd.org> Subject: Re: ZFS reservations for type=volume Message-ID: <CAOtMX2jyBH7k1rGZdP3PvHs7j8k=p97XOqJ9GyORaDHxavKtYQ@mail.gmail.com> In-Reply-To: <94c10113c3964b1bbd3f4ddf934c23cd@MAIL-HUB.pai.local> References: <94c10113c3964b1bbd3f4ddf934c23cd@MAIL-HUB.pai.local>
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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 isc= si 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 whi= le I could over provision guests on the provided LUN, > > the storage presented as the LUN capacity will always be available. At l= east this is what I want to achieve. > > > > What I find strange is that the reservation does not seem to be applied t= o the ZFS pool =E2=80=98raid-5400-1=E2=80=99. Do you really need > > to set your maximum reservation at the pool level, and then apply reserva= tions to all datasets on that volume? And if so > > I would assume you could never set reservations for datasets totaling mor= e than what was reserved for the pool =E2=80=98raid-5400-1=E2=80=99. > > > > I could build out a test environment and figure out constraints but I=E2= =80=99d really like to know the =E2=80=9Chow it is supposed to work=E2=80= =9D > > not the =E2=80=9Chow I find it to work=E2=80=9D. > > > > Thanks in advance. > > > > FreeBSD 14.0-CURRENT #4 main-n253875-8e72f458c6d: > > > > (this is a raidz2 pool =E2=80=93 not my draid pool) > > > > > > root@draid:/usr/src/contrib/bearssl # zfs list -o name,type,used,avail,ra= tio,compression,reservation,refreservation,volsize 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,ra= tio,compression,reservation,refreservation,volsize raid-5400-1/esxi-store1 > > NAME TYPE USED AVAIL RATIO COMPRESS RESER= V 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. If the reader > of this message is not the intended recipient, you are hereby > notified that any dissemination, distribution or copying > of this communication is strictly prohibited. If you have > received this transmission in error, please notify us by > telephone at (502) 212-4000 or notify us at: PAI, Dept. 99, > 2101 High Wickham Place, Suite 101, Louisville, KY 40245 > > > > > > Disclaimer > > The information contained in this communication from the sender is confid= ential. It is intended solely for use by the recipient and others authorize= d to receive it. If you are not the recipient, you are hereby notified that= any disclosure, copying, distribution or taking action in relation of the = contents of this information is strictly prohibited and may be unlawful. > > This email has been scanned for viruses and malware, and may have been au= tomatically archived by Mimecast, a leader in email security and cyber resi= lience. Mimecast integrates email defenses with brand protection, security = awareness training, web security, compliance and other essential capabiliti= es. Mimecast helps protect large and small organizations from malicious act= ivity, human error and technology failure; and to lead the movement toward = building a more resilient world. To find out more, visit our website.
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