On Thu, May 31, 2007 at 11:02:06PM -0400, WHIRLYCOTT wrote: > Hi, I'm trying to track down a pretty apparent problem that I'm > having with disk i/o on an Etch box. Basically, I have two identical > machines. One is running Etch and one is running CentOS. The Etch > machine is really slow. I'm trying to figure out why. Details are > as follows: > > Etch: (output of hdparm) > > /dev/sda: > Timing cached reads: 1588 MB in 2.00 seconds = 794.41 MB/sec > Timing buffered disk reads: 176 MB in 3.03 seconds = 58.15 MB/sec > > /dev/sda: > IO_support = 0 (default 16-bit) > readonly = 0 (off) > readahead = 256 (on) > geometry = 30401/255/63, sectors = 488397168, start = 0 > > Linux etch 2.6.18-4-k7 #1 SMP Wed May 9 23:42:01 UTC 2007 i686 GNU/ > Linux > > CentOS: (output of hdparm) > > /dev/sda: > Timing cached reads: 4480 MB in 2.00 seconds = 2242.86 MB/sec > Timing buffered disk reads: 176 MB in 3.03 seconds = 58.16 MB/sec > > /dev/sda: > IO_support = 0 (default 16-bit) > readonly = 0 (off) > readahead = 256 (on) > geometry = 30401/255/63, sectors = 488397168, start = 0 > > Linux centos 2.6.18-8.1.3.el5PAE #1 SMP Mon Apr 30 20:26:37 EDT 2007 > i686 athlon i386 GNU/Linux > > Please note that I'm specifically not trying to spark a centos/debian > war here. I just provide the CentOS numbers because it's the same > hardware and there's a pretty obvious difference between the two > otherwise identical machines. these are cache reads, try running 10 in a row and taking a look at the averages. the other thing i notice is that you have PAE kernel for centos - does this give it access to a large kernel memory space ? > > I'm not sure where to look next. The fact that the hdparm settings > are identical indicate that the problem (or setting?) may be > elsewhere. But where? > > Does anybody have an idea of where to look? > > phil. > > -- > Whirlycott > Philip Jacob > phil@whirlycott.com > http://www.whirlycott.com/phil/ > > > > -- > To UNSUBSCRIBE, email to debian-user-REQUEST@lists.debian.org > with a subject of "unsubscribe". Trouble? Contact > listmaster@lists.debian.org > >
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