Re: RAID 0 not as fast as expected

Josh,

On 9/14/06 8:47 PM, "Joshua D. Drake" <jd(at)commandprompt(dot)com> wrote:

>> I've obtained 1,950 MB/s using Linux software RAID on SATA drives.
>
> With what? :)

Sun X4500 (aka Thumper) running stock RedHat 4.3 (actually CentOS 4.3) with
XFS and the linux md driver without lvm. Here is a summary of the results:

Read Test
RAID Level Max Readahead (KB) RAID Chunksize Max Readahead on Disks (KB)
Max Time (s) Read Bandwidth (MB/s)
0 65536 64 256 16.689 1,917.43
0 4096 64 256 21.269 1,504.54
0 65536 256 256 17.967 1,781.04
0 2816 256 256 18.835 1,698.96
0 65536 1024 256 18.538 1,726.18
0 65536 64 512 18.295 1,749.11
0 65536 64 256 18.931 1,690.35
0 65536 64 256 18.873 1,695.54
0 64768 64 256 18.545 1,725.53
0 131172 64 256 18.548 1,725.25
0 131172 64 65536 19.046 1,680.14
0 131172 64 524288 18.125 1,765.52
0 131172 64 1048576 18.701 1,711.14
5 2560 64 256 39.933 801.34
5 16777216 64 256 37.76 847.46
5 524288 64 256 53.497 598.16
5 65536 32 256 38.472 831.77
5 65536 32 256 38.004 842.02
5 65536 32 256 37.884 844.68
5 2560 16 256 41.39 773.13
5 65536 16 256 48.902 654.37
10 65536 64 256 83.256 384.36
1+0 65536 64 256 19.394 1,649.99
1+0 65536 64 256 19.047 1,680.05
1+0 65536 64 256 19.195 1,667.10
1+0 65536 64 256 18.806 1,701.58
1+0 65536 64 256 18.848 1,697.79
1+0 65536 64 256 18.371 1,741.88
1+0 65536 64 256 21.446 1,492.12
1+0 65536 64 256 20.254 1,579.93