Hi again,
just thought I should re-post and add the 12disk raid0 stats here as well:
On Mon, 18 Aug 2008, Jan Wagner wrote:
When I used '&' backgrounding the results were the same.
But let's redo it, for completeness, three 4disk raid0 in parallel:
oper@abidal:~$ sudo /usr/bin/time dd if=/dev/zero of=/dev/md0 bs=1024k
count=48000 &
[1] 13283
oper@abidal:~$ sudo /usr/bin/time dd if=/dev/zero of=/dev/md1 bs=1024k
count=48000 &
[2] 13286
oper@abidal:~$ sudo /usr/bin/time dd if=/dev/zero of=/dev/md2 bs=1024k
count=48000 &
[3] 13288
48000+0 records in
48000+0 records out
50331648000 bytes (50 GB) copied, 218.485 s, 230 MB/s
0.07user 147.77system 3:38.50elapsed 67%CPU (0avgtext+0avgdata 0maxresident)k
48inputs+98304008outputs (1major+520minor)pagefaults 0swaps
48000+0 records in
48000+0 records out
50331648000 bytes (50 GB) copied, 218.206 s, 231 MB/s
0.05user 145.51system 3:38.20elapsed 66%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+98304008outputs (0major+521minor)pagefaults 0swaps
48000+0 records in
48000+0 records out
50331648000 bytes (50 GB) copied, 218.895 s, 230 MB/s
0.06user 137.92system 3:38.89elapsed 63%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+98304008outputs (0major+520minor)pagefaults 0swaps
And a single 12disk raid0:
oper@abidal:~$ sudo /usr/bin/time dd if=/dev/zero of=/dev/md0 bs=1024k
48000+0 records in
48000+0 records out
50331648000 bytes (50 GB) copied, 106.334 s, 473 MB/s
0.10user 90.41system 1:46.38elapsed 85%CPU (0avgtext+0avgdata
0maxresident)k
88inputs+98304000outputs (2major+526minor)pagefaults 0swaps
The Dirty/Writeback values were at
http://www.metsahovi.fi/~jwagner/10g-tests/pmp/linux-raid-1.txt
For the 3 x 4disk raid0s the values were ~390MB Writeback and ~14MB
Dirty. Aggretate write rate 690MB/sec.
For the 1 x 12disk raid0 just ~14MB Writeback and ~190MB Dirty. Write
rate 473 MB/sec.
Didn't mention before but the kernel is the Ubuntu 2.6.24-19-generic SMP,
and it is on a 4 core system. I also booted with 'nosmp', but all the
write rates were approximately the same.
Do you have any more thoughts or possible tests?
Perhaps I should read up on a kernel profiling howto...?
Kind regards,
- Jan
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