> -----Original Message-----
> From: centos-bounces@xxxxxxxxxx
> [mailto:centos-bounces@xxxxxxxxxx] On Behalf Of Craig White
> Sent: Saturday, January 13, 2007 12:40 AM
> To: CentOS mailing list
> Subject: Re: 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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