Date: Wed, 27 Apr 2016 14:05:12 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> To: Andy Farkas <andyf@andyit.com.au>, 'PK1048' <paul@pk1048.com> Cc: freebsd-fs@freebsd.org Subject: Re: How to speed up slow zpool scrub? Message-ID: <5720AAF8.4090900@quip.cz> In-Reply-To: <084201d1a03e$d2158fe0$7640afa0$@andyit.com.au> 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>
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Andy Farkas wrote on 04/27/2016 06:39:
>> -----Original Message-----
>> From: PK1048 [mailto:paul@pk1048.com]
>> Sent: Wednesday, 27 April 2016 12:34 PM
>> To: Andy Farkas <andyf@andyit.com.au>
>> Cc: freebsd-fs@freebsd.org
>> Subject: Re: How to speed up slow zpool scrub?
>>
>> ...
>> Scrubs (and resilver) operations are essentially all random I/O. Those
>> drives are low end, low performance, desktop drives.
>
> Yes, the system is an old low end, low performance desktop. That was
> my point, that it took 25 hours to scrub 7.52T and not 4 days like the
> OP is saying.
Thank you for output of your zpool scrub. It is definitely faster than mine.
To: Paul pk1048
Mine scrub does not repair anything. Drives are OK (in SMART).
CPU is about 70%-90% idle during scrub + rsync backup and drives are
about 60%-70% busy according to iostat:
root@kiwi ~/# iostat -x -w 10 ada0 ada1 ada2 ada3
extended device statistics
device r/s w/s kr/s kw/s qlen svc_t %b
ada0 70.1 17.9 1747.0 802.4 0 7.0 24
ada1 70.1 17.9 1747.1 802.4 0 7.0 25
ada2 66.9 17.1 1686.4 791.3 4 6.5 23
ada3 66.9 16.9 1686.3 790.1 2 6.6 23
extended device statistics
device r/s w/s kr/s kw/s qlen svc_t %b
ada0 93.6 13.0 576.4 244.0 0 21.6 70
ada1 98.6 12.9 587.2 246.4 2 20.5 71
ada2 87.9 15.3 566.0 242.4 3 20.5 67
ada3 84.9 14.5 549.2 237.2 3 20.4 66
extended device statistics
device r/s w/s kr/s kw/s qlen svc_t %b
ada0 98.7 42.5 1924.7 2536.3 1 26.3 86
ada1 99.1 45.5 1931.5 2671.5 1 23.8 87
ada2 94.2 44.9 1840.7 2720.3 0 20.1 76
ada3 93.6 42.7 1807.9 2607.1 0 18.7 75
extended device statistics
device r/s w/s kr/s kw/s qlen svc_t %b
ada0 108.2 28.2 1092.6 1316.6 2 17.3 68
ada1 101.6 26.3 1053.8 1183.4 3 15.5 67
ada2 98.6 26.0 1000.2 1126.2 2 12.2 57
ada3 104.0 24.0 1015.8 1080.6 3 14.1 60
extended device statistics
device r/s w/s kr/s kw/s qlen svc_t %b
ada0 116.0 18.5 821.8 807.8 0 12.9 62
ada1 117.2 18.5 822.2 807.0 0 13.5 63
ada2 110.8 20.9 743.0 803.8 0 11.1 58
ada3 108.2 20.0 688.2 755.0 2 11.3 55
extended device statistics
device r/s w/s kr/s kw/s qlen svc_t %b
ada0 121.8 16.6 602.1 526.9 3 9.2 52
ada1 122.2 16.5 606.9 528.5 4 9.8 54
ada2 117.0 14.6 601.7 524.9 2 11.3 60
ada3 120.6 13.5 610.1 491.3 0 11.4 61
I really don't know why it cannot go faster if nothing is loaded for 100%.
Miroslav Lachman
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