FreeBSD: vfs.read_max for Hardware RAID

jnlin — Mon, 03 Mar 2008 05:46:18 +0000

Tested with: bonnie -s 2048, FreeBSD 7.0 UFS2 , Hardware RAID 5 (6 PATA 7200rpm 250G disks)
vfs.read_max=8 (default)

-------Sequential Output-------- -Per Char- --Block--- -Rewrite-- Machine MB K/sec %CPU K/sec %CPU K/sec %CPU 2048 25812 24.8 26483 6.6 13886 4.4 ---Sequential Input-- --Random-- -Per Char- --Block--- --Seeks--- K/sec %CPU K/sec %CPU /sec %CPU 32162 32.5 33386 5.1 232.3 1.5

vfs.read_mas=128

-------Sequential Output-------- -Per Char- --Block--- -Rewrite-- Machine MB K/sec %CPU K/sec %CPU K/sec %CPU 2048 25380 24.3 25949 6.5 13956 4.3 ---Sequential Input-- --Random-- -Per Char- --Block--- --Seeks--- K/sec %CPU K/sec %CPU /sec %CPU 41060 43.4 42839 8.3 224.9 1.4

vfs.read_max=256

-------Sequential Output-------- -Per Char- --Block--- -Rewrite-- Machine MB K/sec %CPU K/sec %CPU K/sec %CPU 2048 25714 24.3 25939 6.5 13966 4.3 ---Sequential Input-- --Random-- -Per Char- --Block--- --Seeks--- K/sec %CPU K/sec %CPU /sec %CPU 41442 43.8 43737 8.6 225.2 1.5

Conclusion: No performance gain on random access, but about 25% better sequential read performance.

FreeBSD gjournal and UFS snapshot

jnlin — Thu, 28 Feb 2008 16:33:53 +0000

Recently I am testing a new feature in FreeBSD 7.0: gjournal. However, taking a snapshot on a journalized ufs causes kernel panic. (Size of the RAID is 5TB)

And I cannot write into the filesystem when I am taking a snapshot, and ever can not read data from it. We should use ZFS or NetApp when we need filesystem snapshot in FreeBSD…

Jui-Nan Lin's Blog » ufs

FreeBSD: vfs.read_max for Hardware RAID

FreeBSD gjournal and UFS snapshot