Date: Thu, 28 Apr 2016 09:52:45 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> To: Steven Hartland <killing@multiplay.co.uk>, freebsd-fs@freebsd.org, Adam Nowacki <nowakpl@platinum.linux.pl> Subject: Re: How to speed up slow zpool scrub? Message-ID: <5721C14D.8@quip.cz> In-Reply-To: <572124CC.6050808@multiplay.co.uk> References: <698816653.2698619.1461685653634.JavaMail.yahoo.ref@mail.yahoo.com> <698816653.2698619.1461685653634.JavaMail.yahoo@mail.yahoo.com> <571F9897.2070008@quip.cz> <571FEB34.7040305@andyit.com.au> <56C0A956-F134-4A8D-A8B6-B93DCA045BE4@pk1048.com> <084201d1a03e$d2158fe0$7640afa0$@andyit.com.au> <5720AAF8.4090900@quip.cz> <5720F890.3040600@platinum.linux.pl> <572100C9.8010606@quip.cz> <57211EFF.4000000@platinum.linux.pl> <572124CC.6050808@multiplay.co.uk>
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Steven Hartland wrote on 04/27/2016 22:45:
>
>
> On 27/04/2016 21:20, Adam Nowacki wrote:
[...]
>>>> 2) some data blocks do not span all disks (metadata, small files,
>>>> compression)
>>>> End result is that zfs can't always read from all disks during scrub so
>>>> disk utilization is going to be less than 100% even when going at full
>>>> speed.
>>> Thank you for the explanation.
>> Try increasing vfs.zfs.top_maxinflight to 100 or more.
>>
> If your on a recent version vfs.zfs.vdev.scrub_max_active is usually the
> most pertinent change to make.
Thank you to both of you. It seems that vfs.zfs.top_maxinflight=128 did
higher disk utilization (about 90%).
Scrubbing is over after 4 days so I will play with these sysctls next time
# zpool status -v tank0
pool: tank0
state: ONLINE
scan: scrub repaired 0 in 96h27m with 0 errors on Thu Apr 28 03:29:21
2016
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
Thank you!
Miroslav Lachman
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