chrism@imntv.com wrote:
Bowie Bailey wrote:
Joshua Baker-LePain wrote:
On Thu, 12 Oct 2006 at 4:22pm, Bowie Bailey wrote
I have two identical servers. The only difference is that the first one has Maxtor 250G drives and the second one has Seagate 320G drives.
OS: CentOS-4.4 (fully patched) CPU: dual Opteron 280 Memory: 16GB Raid card: 3ware 9550Sx-8LP Raid volume: 4-disk Raid 5 with NCQ and Write Cache enabled
On the first server I have decent performance. Nothing spectacular, but good enough. The second one has about 1/3 the write speed. I can't find any difference between the systems. Both of them have the same stripe size, both have ext3 filesystems, both have write caching and NCQ turned on. I have already increased the read ahead setting to 16384 on both servers.
Turn off NCQ. Last I knew, this was still 3ware's recommendation.
I can try that, but when I tested on the first server, I found that disabling NCQ increased the read performance by 10M/s and decreased the write performance by 10M/s. Maybe I'll get different results from the Seagate drives.
Here's what I'm getting from a dual Opteron 275 box, Centos 4.4-64bit, 2gb RAM and an 8 drive array of 750gig Seagates:
Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP localhost.locald 4G 248901 96 138957 40 308874 42 625.8
I've been applying all the various tricks that came up during the last couple of threads. Turning NCQ off definitely made a big difference for me.
With NCQ off, I get these results:
Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP Second 50G 20853 8 41899 11 192713 23 116.9 1
Write performance increased by 2M/s and read performance decreased by 2M/s.
What tweaks have you applied so far? I would expect a 4-drive array to be slower than an 8-drive array, but not this much!
On Thu, 12 Oct 2006 at 7:58pm, Bowie Bailey wrote
With NCQ off, I get these results:
Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP Second 50G 20853 8 41899 11 192713 23 116.9 1
Write performance increased by 2M/s and read performance decreased by 2M/s.
What tweaks have you applied so far? I would expect a 4-drive array to be slower than an 8-drive array, but not this much!
What's your StorSave profile set to?
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Bowie Bailey -
Joshua Baker-LePain