Messages in this thread |  | | From | "Ryan Shrout" <> | Subject | Slow SCSI Disk Access on AMI Elite 1600 controller | Date | Tue, 14 Aug 2001 16:32:24 -0400 |
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Okay, I am fairly new to all this, so bear with me as I try to explain the problem fully. :)
First, my problem was centered around Mysql. I had a problem of processes spawning and spawning (sometimes over 100 of them at a time). A simply mysqld restart would solve the matter for most of the day, but the problem always persisited. One the people in the mysql list pointed me to check my disk performance. I came up with this:
[root@dagger /root]# hdparm -Tt /dev/sda
/dev/sda: Timing buffer-cache reads: 128 MB in 0.93 seconds =137.63 MB/sec Timing buffered disk reads: 64 MB in 13.92 seconds = 4.60 MB/sec
My systems specs are: Tyan Thunder K7 Dual-Athlon (non-Via chipsets) motherboard 2 - 1.2 Ghz Athlon MP CPUs 1 GB PC2100 Registered DDR DRAM AMI Elite 1600 SCSI RAID controller with 64 MB SDRAM 4 - 15K RPM Cheetah SCSI HDDs Red Hat Linux 7.2
Obivously, 4.60 MB/sec is WAY too slow for this setup, and the mysql people assumed this was probably what was causing the Mysqld server to crap out.
So, I then started trying to figure out to raise the buffered disk read speed. My only solution I came across -- find out if the SCSI controllers/drives were in asynchronous mode and if they are, change them to synchronous mode.
Now, how can I tell what mode my SCSI disks are in and how can I change it to synchronous if it isn't set that way already?
Thank you!!!
Ryan Shrout Owner - Amdmb.com http://www.amdmb.com/ rshrout@amdmb.com
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