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Bonnie numbers for RAID-6

DISCUSSION H. Peter Anvin 1 participant 1 message Dec 27, 2003 MD RAID

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H. Peter Anvin

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Some quick Bonnie numbers run on the RAID-6 code. The machine has one P4/1.8 CPU and 512 MB RAM; the file size was 1024 MB and the filesystem a "virgin" ext3. Each partition was 10 GB; each disk is a 40 GB ATA/100 drive. The stripe size was 256 KB.

I suspect RAID-6 write performance should be possible to improve; currently it doesn't do read-modify-write for the syndrome drives, for example.

RAID-6 across 6 disks:

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
         1024  4579 95.7 21733  8.4 10993  4.1  4483 93.8 28751  6.5 331.5  3.0

RAID-5 across 5 disks (same capacity):

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
         1024  4622 96.4 56730 23.5 17249  6.4  4651 97.4 29761  6.1 322.4  2.8

RAID-5 across 6 disks:

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
         1024  4597 96.0 28771 11.2 12890  4.7  4558 95.4 29133  6.5 344.3  3.0

Single disk:

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
         1024  4738 98.8 33435 14.2 16157  5.9  4718 97.7 34268  4.3 151.3  0.7
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