Re: RAID Sync Speeds

[Chris Boot <bootc@bootc.net>]

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

> Hi,
>    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,
> than
> /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
> around
> 500000 and leave the min at 5000. But with idle disk activity and
> otherwise
> 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.

HTH,
Chris

-- 
Chris Boot
bootc@bootc.net
http://www.bootc.net/