my reiser raid0 benchmarks for 32K and 64K chunk sizes
 

Hey all,

I never found a straight answer to which is a better chunk size for a reiserfs raid0 install. So i decided to run my own benchmarks. I ran 10 benchmarks for each chunk size with about 10 seconds inbetween each benchmark. Benchmarks were done in the order they are presented, and I did about a 3 minute HD cooldown between the 32K benchmarks and 64K benchmarks. I used two 160GB Western Digital SATA HD's to do the benchmarks:


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32K Chunk Size over 10 Runs:

Average timing cached reads: 1896.111 MB/sec
Average timing buffer disk reads: 62.243 MB/sec

Timing cached reads: 3728MB in 2.00 seconds = 1863.35 MB/sec
Timing buffer disk reads: 186MB in 3.02 seconds = 61.52 MB/sec

Timing cached reads: 3840MB in 2.00 seconds = 1920.29 MB/sec
Timing buffer disk reads: 190MB in 3.03 seconds = 62.67 MB/sec

Timing cached reads: 3828MB in 2.00 seconds = 1913.33 MB/sec
Timing buffer disk reads: 188MB in 3.03 seconds = 62.06 MB/sec

Timing cached reads: 3820MB in 2.00 seconds = 1910.29 MB/sec
Timing buffer disk reads: 188MB in 3.00 seconds = 62.61 MB/sec

Timing cached reads: 3804MB in 2.00 seconds = 1902.29 MB/sec
Timing buffer disk reads: 188MB in 3.00 seconds = 62.63 MB/sec

Timing cached reads: 3804MB in 2.00 seconds = 1901.34 MB/sec
Timing buffer disk reads: 186MB in 3.00 seconds = 61.93 MB/sec

Timing cached reads: 3764MB in 2.00 seconds = 1881.35 MB/sec
Timing buffer disk reads: 188MB in 3.02 seconds = 62.20 MB/sec

Timing cached reads: 3776MB in 2.00 seconds = 1888.29 MB/sec
Timing buffer disk reads: 190MB in 3.02 seconds = 62.82 MB/sec

Timing cached reads: 3784MB in 2.00 seconds = 1892.29 MB/sec
Timing buffer disk reads: 188MB in 3.04 seconds = 61.85 MB/sec

Timing cached reads: 3776MB in 2.00 seconds = 1888.29 MB/sec
Timing buffer disk reads: 188MB in 3.03 seconds = 62.14 MB/sec

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64K Chunk Size over 10 Runs:

Average timing cached reads: 1903.9 MB/sec
Average timing buffer disk reads: 65.475 MB/sec

Timing cached reads: 3816MB in 2.00 seconds = 1908.29 MB/sec
Timing buffer disk reads: 194MB in 3.01 seconds = 64.40 MB/sec

Timing cached reads: 3808MB in 2.00 seconds = 1903.34 MB/sec
Timing buffer disk reads: 198MB in 3.02 seconds = 65.53 MB/sec

Timing cached reads: 3832MB in 2.00 seconds = 1916.29 MB/sec
Timing buffer disk reads: 198MB in 3.02 seconds = 65.66 MB/sec

Timing cached reads: 3780MB in 2.00 seconds = 1890.29 MB/sec
Timing buffer disk reads: 198MB in 3.01 seconds = 65.77 MB/sec

Timing cached reads: 3820MB in 2.00 seconds = 1909.34 MB/sec
Timing buffer disk reads: 198MB in 3.02 seconds = 65.55 MB/sec

Timing cached reads: 3832MB in 2.00 seconds = 1916.29 MB/sec
Timing buffer disk reads: 198MB in 3.01 seconds = 65.77 MB/sec

Timing cached reads: 3812MB in 2.00 seconds = 1906.29 MB/sec
Timing buffer disk reads: 198MB in 3.02 seconds = 65.51 MB/sec

Timing cached reads: 3756MB in 2.00 seconds = 1878.29 MB/sec
Timing buffer disk reads: 198MB in 3.02 seconds = 65.57 MB/sec

Timing cached reads: 3788MB in 2.00 seconds = 1894.29MB/sec
Timing buffer disk reads: 198MB in 3.02 seconds = 65.53 MB/sec

Timing cached reads: 3832MB in 2.00 seconds = 1916.29 MB/sec
Timing buffer disk reads: 198MB in 3.02 seconds = 65.46 MB/sec

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My results seem to hint at a 64K chunk size being best for a reiserfs raid0 install. I hope this helps people in the future make the decision. Comments and questions are welcome :)

- George

hdparm is ok to get an estimate on raw performance. It does not count for filesystem or how well it will do on small files and large files. I suggest using bonnie or other disk benchmark utilities that tests the filesystem and the hard drive performance as one.

RAID 0 does nothing to speed up OS performance. RAID 1 should be used because two request can be handled at a time instead of one request for RAID 0. RAID 0 should be used for video recording, sound recording, graphics editing, or transfering huge files (>60 MB) over a 1 gigabit network.