> -----Original Message----- > From: centos-bounces at centos.org > [mailto:centos-bounces at 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 at 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 ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.