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Gmane

From: Christ Schlacta <aarcane-s0m2ZJPhe3VAfugRpC6u6w <at> public.gmane.org>
Subject: Re: Speed up a scrub
Newsgroups: gmane.linux.file-systems.zfs.user
Date: Thursday 29th September 2011 20:01:58 UTC (over 7 years ago)
On 9/29/2011 10:53, Brian Behlendorf wrote:
> You could try increasing zfs_top_maxinflight.  This is used to limit the
> number of outstanding scrub/resilver requests per-top-level vdev.
> Increasing this may allow more outstanding reads to the disks unless
> they are already saturated.
>
even with zfs_top_maxinflight I'm still getting really low speeds.  
Behold the following output:

Those are all the values I've currently set, and can't get zfs to go 
faster than about 13MB for a scrub even with the maximum value for all 
(that I know of) relevant limits, and 0 for all (that I know of) 
relevant delays.  I think I might smell a bug, but if there's anything I 
can test first before I file a report, let me know~


[email protected]:/sys/module/zfs/parameters# cat zfs_top_maxinflight
2147483647
[email protected]:/sys/module/zfs/parameters# cat zfs_scrub_delay
0
[email protected]ity:/sys/module/zfs/parameters# cat zfs_resilver_delay
0
[email protected]:/sys/module/zfs/parameters# cat zfs_scan_idle
0
[email protected]:/sys/module/zfs/parameters# cat zfs_scrub_limit
2147483647
[email protected]:/sys/module/zfs/parameters# zpool scrub -s tank
[email protected]:/sys/module/zfs/parameters# zpool scrub tank
[email protected]:/sys/module/zfs/parameters# sleep 60;
[email protected]:/sys/module/zfs/parameters# zpool iostat tank 1 10
                capacity     operations    bandwidth
pool        alloc   free   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
tank        4.25T  1.20T    107     23  1.94M   295K
tank        4.25T  1.20T    113      0  13.1M      0
tank        4.25T  1.20T    140      0  13.2M      0
tank        4.25T  1.20T    113      0  12.2M      0
tank        4.25T  1.20T    123      0  12.2M      0
tank        4.25T  1.20T    103      0  11.5M      0
tank        4.25T  1.20T    120     89  9.93M   235K
tank        4.25T  1.20T    105      0  11.3M      0
tank        4.25T  1.20T    113      0  12.4M      0
tank        4.25T  1.20T    126      0  12.4M      0
[email protected]:/sys/module/zfs/parameters# dd if=/tank/1.2.GB.file 
of=/dev/null bs=8192
143236+1 records in
143236+1 records out
1173393094 bytes (1.2 GB) copied, 6.15325 s, 191 MB/s
[email protected]:/sys/module/zfs/parameters#
 
CD: 41ms