Hi!
I am currently experimenting with the Software RAID (patch for 2.2.11
applied to 2.2.12 with raidtools snapshot from about three weeks ago).
The system I am doing these tests on is an older K5-100 with 64 MB
RAM. For RAID, I have three Quantum Atlas I on a single Fast SCSI Host
Adapter with NCR Chipset. The system itself is installed on a fourth
disk that isn't included in the RAID. The system disk is also used as
a source disk
for the copy tests.
Main test is bonnie with a 300 MB file.
For the copy tests, I use the file and directory structure of a
Windows NT 4.0 installation CD because it has many small files.
"Copy 1" is the time taken for "cp -R 1 /mnt/raid/1/". The source
directory is on the system disk, the target directory on the RAID.
This test is meant to check write rate of the RAID but will measure
source disk performance instead because the source disk is likely to
be the bottle neck here.
"Copy 2" is the time taken for "cp -R 1 2" , with both source and
target directory on the RAID array. I hope to simulate a realistic
usage profile with many small files, read and write operations.
"Copy 3" is the time taken for "tar cf - 1/* 2/* | cat > /dev/null". I
needed to use tar|cat because directories can't be copied to /dev/null
and tar notices that it is writing to /dev/null. I don't believe it to
copy 700 MB in 20 seconds.
Here are my results:
| Bonnie
|
|Chunk Block Stride Out Char Out Block Out Rewri In Char
| In Block Random Copy 1 Copy 2 Copy 3
|Size Size KB CPU KB CPU KB CPU KB CPU
| KB CPU KB CPU mm:ss mm:ss mm:ss
|32 4 8 1767 81,7 4375 35,7 2653 40,2 2247 94,3
| 7386 40,9 166,7 11,6 06:48 07:20 07:04
|4 4 8 1750 80,5 4629 36,7 2544 43,4 2075 91,3
| 5796 36,6 118,8 8,2
|4 4 1 1701 77,6 4364 35,5 2361 40,1 1771 79,2
| 5822 36,6 119,1 7,8 06:52 07:40 07:51
|256 4 64 1750 80,8 4747 36,8 2437 34,1 1917 79,5
| 6918 35,5 173,9 10,9 07:01 08:02 07:45
|64 4 16 1748 80,7 4584 36,4 2757 39,9 2244 93,8
| 7526 40,2 171,6 11,7 06:52 07:50 07:28
|16 4 4 1761 81,6 4591 37,1 2579 39,1 2222 93,7
| 6977 37,1 160,3 11,3 07:01 07:39 07:09
|
|
|a single disc w/o RAID 2087 96 7079 57,8 3067 42,8 1936 81,8
| 6707 34,8 105,5 7 05:15 06:15 06:00
I am quite astonished that the chunk size doesn't seem to have a large
impact on array performance and suspect that I inadvertendly measured
something else than RAID performance.
Second source of astonishment is that the RAID array is quite slower
than a single disk. Under these circumstances, I'd better refrain from
putting a news spool on the RAID array, right? With this performance,
the RAID array can only be used as a safety measure to be able to
recover from a drive failure for system and home directories.
Out of academic interest only, I put a second identical SCSI host
adapter into the system and moved two of the RAID disk to the second
SCSI bus. The third RAID disk and the system disk remained on the
first SCSI bus.
This is what I clocked with that setup.
| Bonnie
|
|Chunk Block Stride Rich- Out Char Out Block Out Rewri In
|Char In Block Random Copy 1 Copy 2 Copy 3
|Size Size tig? KB CPU KB CPU KB CPU KB
| CPU KB CPU KB CPU mm:ss mm:ss mm:ss
|32 4 8 ja 1712 78,7 4375 35,5 3249 48,2 2266
| 95,1 9478 56,7 170 10,6 05:43 06:14 06:48
Even these values are mainly below the performance of a single Atlas
disk. Having taken care of the bottleneck of the single Fast SCSI bus,
I don't know what still is the problem here. Is it possible that my
old 100 MHz CPU is the bottleneck in this system?
Any hints and comments will be appreciated.
Greetings
Marc
--
-------------------------------------- !! No courtesy copies, please !! -----
Marc Haber | " Questions are the | Mailadresse im Header
Karlsruhe, Germany | Beginning of Wisdom " | Fon: *49 721 966 32 15
Nordisch by Nature | Lt. Worf, TNG "Rightful Heir" | Fax: *49 721 966 31 29
