I'm benchmarking an application on two identical servers, one is Centos 5.8 and the other is Centos 6.2. My application is running much slower (50% or less) on the Centos 6.2 machine.
In attempting to diagnose the issue I'm tracking CPU, RAM, and IO throughout the benchmark run. I see that the disk reads are significantly higher on the Centos 6.2 box, as measured with iostat.
Both systems are running XFS where my benchmark is running. Both are HP servers with 512MB caching RAID controllers with 8 x 300GB SAS running RAID 10.
Here is the output of xfs_info for each:
meta-data=/dev/cciss/c0d0p5 isize=256 agcount=32, agsize=8034208 blks = sectsz=512 attr=0 data = bsize=4096 blocks=257094144, imaxpct=25 = sunit=32 swidth=128 blks, unwritten=1 naming =version 2 bsize=4096 log =internal bsize=4096 blocks=32768, version=1 = sectsz=512 sunit=0 blks, lazy-count=0 realtime =none extsz=4096 blocks=0, rtextents=0
meta-data=/dev/sda5 isize=256 agcount=4, agsize=57873856 blks = sectsz=512 attr=2 data = bsize=4096 blocks=231495424, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 log =internal bsize=4096 blocks=113034, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0