-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Craig White Sent: Saturday, January 13, 2007 12:40 AM To: CentOS mailing list Subject: Re: [CentOS] slow system
On Fri, 2007-01-12 at 23:16 -0600, Les Mikesell wrote:
Craig White wrote:
I have software RAID level 1 and the mirrored drives
are the master &
slave on the primary controller and I'm thinking that
is my mistake.
Is there a simple method for changing the configuration
of md before I
switch the slave drive to be the slave on the secondary
controller?
I think they will pair up automatically if you shut down cleanly and move the connector. If not, just 'mdadm --add' it back after it comes up with a missing member. If you have to add it back, the drives will have to resync so there is a small risk of failure during the process.
great thanks - am I right in thinking that having both
mirrored drives
on the same controller master/slave is likely a cause of slowness?
It will make some difference on writes, but reads should only be done on one of the drives anyway. I doubt if it makes a huge difference unless you have an application writing all the time.
here's my problem - system was ok and mother board died. Purchased a new motherboard and this is what I get...
# hdparm -t /dev/md1
/dev/md1: Timing buffered disk reads: 4 MB in 3.68 seconds = 1.09 MB/sec
which is dreadfully slow
Something is definitely not right here. I have an old Dell Dimension (1GHz, 512MB) at home here that I have FC5 on, the drives are on the first channel master/slave mirrored, cheapo 100GB WDs. Here is what I get:
[root@gandalf linux]# hdparm -t /dev/md1
/dev/md1: Timing buffered disk reads: 72 MB in 3.00 seconds = 23.96 MB/sec
Now that is what I call slow, what you are getting is unusable.
I'd put then on separate channels, but I have an LS-120 drive in PIO, and a CDRW running at like DMA2, and it would be a lot worse to share a channel with one of those.
-Ross
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