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Re: "Misbehaving" hard disk or weird RAIDframe problem

On 12 Jan 2009, at 19:12, Greg Oster wrote:
What happens if you do both of the above dd's simultaneously?

No problems.

Do you see the same levels of performance, or does it drop off

Both harddisks deliver data at over 75MB/s.

Is the write cache turned off on one of the drives?


Yes, of course. That's it. And the really annoying bit is that
I knew that. When that disk was the only disk in the system
I had the following bit in "/etc/rc.local":

echo -n "Turning on disk write-cache ... "
dkctl wd0 setcache rw && echo "done."

But I commented it out when I replaced that disk with two
newer hard disks. Running it immediately fixes the problem:

tron@colwyn:~tron#dkctl wd2 setcache rw
tron@colwyn:~tron#dd if=/dev/zero of=/dev/rwd2d bs=1m count=256256+0 records in
256+0 records out
268435456 bytes transferred in 3.453 secs (77739778 bytes/sec)

        Thanks a great lot

Matthias Scheler                 

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