Date: Tue, 26 Apr 2016 16:27:57 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> To: krad <kraduk@gmail.com> Cc: jg@internetx.com, FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: How to speed up slow zpool scrub? Message-ID: <571F7AED.2040500@quip.cz> In-Reply-To: <CALfReyc9ki3-wEhkvvv=4TR28Nk0H0SvH8FAW=ev7H7Zu0oQoA@mail.gmail.com> References: <571F62AD.6080005@quip.cz> <571F687D.8040103@internetx.com> <571F6EA4.90800@quip.cz> <CALfReyc9ki3-wEhkvvv=4TR28Nk0H0SvH8FAW=ev7H7Zu0oQoA@mail.gmail.com>
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krad wrote on 04/26/2016 16:02: > Erk, i would try to move your system off those data disks as you have > two pools competing for the disk spindles. This is never ideal. You can > by all means backup your os to those data pools but keep them on > separate physical mediums. A couple of small SSD would do the trick > nicely and could probably be added with no down time. You would probably > want to find a suitable window though to make sure the box reboots > nicely though. The system pool is really small - only 15GB and scrub is done relatively fast. This machine cannot handle additional disks so I cannot move system to other devices anyway. I tried system on USB flashdisk (read only) in the past but it was slow and USB disk broke early. > On 26 April 2016 at 14:35, Miroslav Lachman <000.fbsd@quip.cz > <mailto:000.fbsd@quip.cz>> wrote: > > InterNetX - Juergen Gotteswinter wrote on 04/26/2016 15:09: > > to speed up the scrub itself you can try > > sysctl -w vfs.zfs.scrub_delay = 4 (default, 0 means higher prio) > > > I will try it in the idle times > > but be careful as this can cause a serious performance impact, > the value > can be changed on the fly > > your pool is raidz, mirror ? dedup is hopefully disabled? > > > I forgot to mention it. Disks are partitioned to four partitions: > > # gpart show -l ada0 > => 34 7814037101 ada0 GPT (3.6T) > 34 6 - free - (3.0K) > 40 1024 1 boot0 (512K) > 1064 10485760 2 swap0 (5.0G) > 10486824 31457280 3 disk0sys (15G) > 41944104 7769948160 4 disk0tank0 (3.6T) > 7811892264 2144871 - free - (1.0G) > > diskXsys partitions are used for base system pool which is 4-way mirror > > diskXtank0 partitions are used for data storage as RAIDZ > > # zpool list > NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH > ALTROOT > sys 14.9G 11.0G 3.92G - 79% 73% 1.00x ONLINE - > tank0 14.4T 10.8T 3.56T - 19% 75% 1.00x ONLINE - > > > # zpool status -v > pool: sys > state: ONLINE > scan: scrub repaired 0 in 1h2m with 0 errors on Sun Apr 24 > 04:03:54 2016 > config: > > NAME STATE READ WRITE CKSUM > sys ONLINE 0 0 0 > mirror-0 ONLINE 0 0 0 > gpt/disk0sys ONLINE 0 0 0 > gpt/disk1sys ONLINE 0 0 0 > gpt/disk2sys ONLINE 0 0 0 > gpt/disk3sys ONLINE 0 0 0 > > errors: No known data errors > > pool: tank0 > state: ONLINE > scan: scrub in progress since Sun Apr 24 03:01:35 2016 > 7.63T scanned out of 10.6T at 36.7M/s, 23h32m to go > 0 repaired, 71.98% done > config: > > NAME STATE READ WRITE CKSUM > tank0 ONLINE 0 0 0 > raidz1-0 ONLINE 0 0 0 > gpt/disk0tank0 ONLINE 0 0 0 > gpt/disk1tank0 ONLINE 0 0 0 > gpt/disk2tank0 ONLINE 0 0 0 > gpt/disk3tank0 ONLINE 0 0 0 > > errors: No known data errors > > > # zdb | grep ashift > ashift: 12 > ashift: 12 > > > Thank you for your informations. > >
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