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Date: Thu, 24 May 2001 20:00:01 +0000
From: =?us-ascii?Q?Jos=E9_Luis_Domingo_L=F3pez?= <jdomingo@internautas.org>
Subject: Re: [linux-lvm] Raid5 sync problem
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On Thursday, 24 May 2001, at 11:04:27 -0600,
Andreas Dilger wrote:

> Kaj-Michael Lang writes:
> [...]
> This is the "RAID5 speed limit" which only kicks in if you have I/O to
> the volume while you are resyncing.  You can change a parameter somewhere
> in the RAID code which increases the minimum speed at which resync is
> done on active volumes (at the expense of performance for other apps).
> 
Under 2.4.x there are two "tunnables" on /proc, namely:
/proc/sys/dev/raid/speed_limit_min
/proc/sys/dev/raid/speed_limit_max

Both are expressed in KB/s. The latter sets the maximun array
reconstruction speed for RAID-1,4,5 (taking available IO), and the former
sets the minimun "guaranteed" reconstruction speed.

At least on my 2.4.4, "minumun speed" is set to 100 KB/s, and "maximun
speed" equals 100000 KB/s, but it seems that array reconstruction always
operate at the minimun guaranteed speed, 100 KB/s.

So echo "5000" > /proc/sys/dev/raid/speed_limit_min should help
determining whether this speed limit is causing the problems described.

-- 
Jos� Luis Domingo L�pez
Linux Registered User #189436     Debian GNU/Linux Potato (P166 64 MB RAM)
 
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