[developer] RE: [zfs] RE: granularity of performance penalty from resilvering

[Steven Hartland]

These are availabe on FreeBSD as well via sysctls:
* vfs.zfs.resilver_delay
* vfs.zfs.scrub_delay
* vfs.zfs.top_maxinflight
* vfs.zfs.resilver_min_time_ms

     Regards
     Steve

On 21/10/2015 02:35, Fred Liu wrote:
>
> Yeah. I want to go the other way. Plus, these settings are only 
> applicable in illumos.
>
> Therefore I decide to give up the hybrid( ssd+sata) solution to 
> underpin applications which need decent RAS.
>
> I am gonna go all-flash array.
>
> Thanks.
>
> Fred
>
> *From:*Jason Matthews [mailto:jason at broken.net]
> *Sent:* 星期三, 十月21, 2015 9:05
> *To:* zfs at lists.illumos.org; Fred Liu; 
> zfs-discuss at list.zfsonlinux.org; developer; freebsd-fs; zfs-discuss
> *Subject:* Re: [zfs] RE: granularity of performance penalty from 
> resilvering
>
>
>
> you could look at these tunables (not the settings themselves)...
>
> these settings actually make resilvers have a higher priority. You 
> obviously would want to go the other way.
>
> j.
>
> |* Prioritize resilvering by setting the delay to zero|
> |set zfs:zfs_resilver_delay = 0 |
>
> * Prioritize scrubs by setting the delay to zero
> set zfs:zfs_scrub_delay = 0
>
> |* resilver for five seconds per TXG|
> |set zfs:zfs_resilver_min_time_ms = 5000|
>
>
> |echo zfs_resilver_delay/w0 | mdb -kw|
> |echo zfs_scrub_delay/w0 |mdb -kw|
> |echo zfs_top_maxinflight/w7f |mdb -kw|
> |echo zfs_resilver_min_time_ms/w1388 |mdb -kw|
>
> On 10/19/2015 11:49 PM, Fred Liu wrote:
>
>     Yes, “zpool scrub –s” can stop the resilvering.
>
>     *From:*Fred Liu
>     *Sent:* 星 期二, 十月20, 2015 12:15
>     *To:* 'zfs-discuss at list.zfsonlinux.org
>     <mailto:zfs-discuss at list.zfsonlinux.org>'; developer; illumos-zfs;
>     freebsd-fs; zfs-discuss
>     *Subject:* granularity of performance penalty from resilvering
>
>     Sorry if is a duplicate thread.
>
>     The last suffering has been lasted for two weeks for we replaced a
>     6TB HDD.
>
>     There should be some IO throttle measure from ZFS software stack.
>     At least, we can try to stop resilvering like scrubbing
>
>     if the realization is quiet complicated.
>
>     Besides that, will nice zil/cache be relief?
>
>     Thanks.
>
>     Fred
>
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