Re: Software RAID level 1 issue

[Paul Clements <Paul.Clements@SteelEye.com>]

3tcdgwg3 wrote:
> 
> This feature works only for raid1, or both raid1 and raid5?

These sysctls work for all md devices, and indeed, they apply to _all_
md devices in the system, they're not per-device.

(of course, by all md devices I mean all md devices that need to do
recovery...which is the raid1 and raid5 ones)

--
Paul


> ----- Original Message -----
> From: "Paul Clements" <Paul.Clements@SteelEye.com>
> To: "3tcdgwg3" <3tcdgwg3@prodigy.net>
> Cc: "Stef Telford" <stef@chronozon.artofdns.com>; "'Greg Rasberry'"
> <rgreg-r@pacbell.net>; "'Linux raid mailing list'"
> <linux-raid@vger.kernel.org>
> Sent: Friday, May 30, 2003 1:31 PM
> Subject: Re: Software RAID level 1 issue
> 
> > 3tcdgwg3 wrote:
> >
> > > If there is a plan to do a "intelligent resync", like some of the raid
> > > controller
> > > vendors offer?  The resync process will be hold on, if there are IO
> requests
> > > from upper level, and resumed when there is no IO.  By doing that, the
> > > system
> > > performance always be on the top.  I am very interested in  having
> something
> > > like that.
> >
> > This wasn't exactly what I meant by intelligent resync, but...I think
> > what you're asking about is something that the md driver already does to
> > some extent. It will slow down a resync if there is active I/O on the
> > device. This can even be tuned by the user by manipulating a couple of
> > kernel sysctls:
> >
> > apache:~# cat /proc/sys/dev/raid/speed_limit_min
> > 100
> >
> > apache:~# cat /proc/sys/dev/raid/speed_limit_max
> > 10000
> >
> > apache:~# echo 1000000 > /proc/sys/dev/raid/speed_limit_max
> >
> > apache:~# cat /proc/sys/dev/raid/speed_limit_max
> > 1000000
> >
> >
> > These are in KB/s.
> >
> > The "min" refers to the maximum I/O bandwidth that will be consumed by
> > resyncs before the resyncs get throttled, when there is other I/O
> > activity on the device.
> >
> > The "max" refers to the maximum I/O bandwidth that will be consumed by
> > resyncs before the resyncs get throttled, even if there is no other I/O
> > activity on the device.
> >
> > --
> > Paul
> 
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