I put it into runlevel 3 and disabled all unnecessary services. Set up a 25GB logical volume formatted XFS. Mounted with Dave's suggested options: inode64,logbsize=262144
iozone -i0 -i1 -i2 -i4 -i8 -l 4 -u 4 -F 1 2 3 4 -s 2g
Which is 4 threads each working with a 2GB file, for a total of 8GB of data.
I got the following throughput numbers:
59794 KB/s Write
60376 KB/s Rewrite
64557 KB/s Read
66706 KB/s Reread
----- Mixed Workload
I stopped the mixed workload test after 45 minutes. vmstat was reporting about 700k/s in, 2k/s out. The drive light was on solid. Iozone was using only a about 2% of processor. This seemed quite puzzling. Tried again. Same result. Switching from CFQ to Deadline or Noop i/o scheduler made no difference. No error messages in the log. And I was on a text console, so would have seen any kernel messages immediately.
I reformatted to ext4 and mounted with default options. I got these results:
68559 KB/s Write
60561 KB/s Rewrite
67697 KB/s Read
69353 KB/s Reread
----- Mixed workload
Better performance than XFS in the other tests. But same problem with Mixed workload.
Obviously, the drive was getting seeked to death. (What else *could* it be?)
So I ran:
iozone -i0 -i8 -l 1 -u 1 -F 1 -s 8g
which runs a single thread on 1 8GB file. Same problem.
I used this same iozone on a Scientific Linux 6.1 server running 3 drive software RAID1 just a few days ago and got really nice numbers for all tests, including mixed workload.
What in the world is going on here???
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