[ale] Linux Raid

[Robert L. Harris]

  Ok, that probably didn't come out right then.  I'm looking for a more
indepth document than the HOWTO without having to read all the source
involved.  Something between the two.

Thus spake Joe Steele (joe at madewell.com):

> From: Joe Steele <joe at madewell.com>
> To: "'Robert L. Harris'" <Robert.L.Harris at rdlg.net>
> Cc: Atlanta Linux Enthusiasts <ale at ale.org>
> Date: Wed, 2 Oct 2002 19:12:52 -0400
> Subject: RE: [ale] Linux Raid
> 
> 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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:wq!
---------------------------------------------------------------------------
Robert L. Harris                
                               
DISCLAIMER:
      These are MY OPINIONS ALONE.  I speak for no-one else.
FYI:
 perl -e 'print $i=pack(c5,(41*2),sqrt(7056),(unpack(c,H)-2),oct(115),10);'


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