[ale] Linux Raid

[Joe Steele]

On Wednesday, October 02, 2002 4:10 PM, Robert L. Harris wrote:
> Perfect.
>
> I'm reading the Software-RAID HOWTO on linux.org and searched both the
> html and pdf versions for "min" and it's not referenced in there.  Any
> other suggestions other than reading kernel driver source?  :>
>

I suggest you read the kern...  Oops.  Sorry, you said you didn't want 
that suggestion.


WARNING -- WARNING -- WARNING:  If you have a strong aversion for reading 
the kernel source, then read no further.





OK.  You've been warned ...

>From linux/drivers/md/md.c:

   /*
    * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
    * is 100 KB/sec, so the extra system load does not show up that much.
    * Increase it if you want to have more _guaranteed_ speed. Note that
    * the RAID driver will use the maximum available bandwith if the IO
    * subsystem is idle. There is also an 'absolute maximum' reconstruction
    * speed limit - in case reconstruction slows down your system despite
    * idle IO detection.
    *
    * you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
    */

   static int sysctl_speed_limit_min = 100;
   static int sysctl_speed_limit_max = 100000;


Now that wasn't so bad, was it?  :)

--Joe
(I know -- asking for "suggestions other than" does not really mean a 
person has any aversion to reading kernel source)


>
> Thus spake Danny Cox (danscox at mindspring.com):
>
> > Subject: Re: [ale] Linux Raid
> > From: Danny Cox <danscox at mindspring.com>
> > To: "Robert L. Harris" <Robert.L.Harris at rdlg.net>
> > Cc: Atlanta Linux Enthusiasts <ale at ale.org>
> > X-Mailer: Ximian Evolution 1.0.8
> > Date: 02 Oct 2002 15:53:43 -0400
> >
> > Robert,
> >
> > On Wed, 2002-10-02 at 15:42, Robert L. Harris wrote:
> > > The neat feature is the 'go ahead and use the raid once built, we'll
> > > sync slowly in the background'...  Does anyone know if there is a way to
> > > force a fast sync with maximum IO bandwidth?  I can't find any way of
> > > doing this.
> >
> >     Sure.  See /proc/sys/dev/raid/speed_limit_min and _max.  Do a "echo
> > 10000 >/proc/sys/dev/raid/speed_limit_min" as root, and it'll speed up
> > quite a bit.
> >
> >     See the Software-RAID HOWTO for more info.
> >

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