Re: RAID Sync Speeds

From: Chris Boot
Date: Mon May 22 2006 - 13:01:56 EST

On 22 May 2006, at 14:05, Rainer Shiz wrote:

I have a general question on operating software RAIDs in linux.
I am running md RAID in linux 2.6.12 kernel. I observed that the
sync speeds
were always much closer to /proc/sys/dev/raid/speed_limit_min value,
/proc/sys/dev/raid/speed_limit_max value. I agree that disk activity
(I/O) and
other system usage will bring down sync speeds. But I want sync speeds
to be
higher at whatever cost. So I thought I will just set max value to
500000 and leave the min at 5000. But with idle disk activity and
idle system usage, I still see sync speeds around 5300Kb/s only.

So Is the 2.6 kernel designed to sync at speeds closer to min than max?

Please advise.

I must admit I keep my settings on the default (1000/200000) and get whatever my disks can handle, usually 50-70MB/sec. All this is on a completely idle system, doing anything disk bound at all will lower these numbers significantly. This is on various SATA controllers, all with Seagate drives.


Chris Boot

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