On Sat, Mar 20, 2010 at 3:49 AM, Gary Gatten <ggat...@waddell.com> wrote:
> It MAY make a big diff, but make sure during your tests you use unique files
> or flush the cache or you'll me testing cache speed and not disk speed.
Yeah I did make sure to use unique files for testing the effects of
prefetch. This is Atom D510 / Supermicro X75SPA-H / 4Gb Ram with 2 x
slow 2tb WD Green (WD20EADS) disks with 32mb cache in a ZFS mirror
after enabling prefetch.:
Code:
bonnie -s 8192
-------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
8192 29065 68.9 52027 39.8 39636 33.3 54057 95.4
105335 34.6 174.1 7.9
DD read:
dd if=/dev/urandom of=test2 bs=1M count=8192
dd if=test2 of=/dev/zero bs=1M
8589934592 bytes transferred in 76.031399 secs (112978779 bytes/sec)
(107,74mb/s)
Individual disks read capability: 75mb/s
Reading off a mirror of 2 disks with prefetch disabled: 60mb/s
Reading off a mirror of 2 disks with prefetch enabled: 107mb/s
- Sincerely,
Dan Naumov
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