Sorry about that in-a-hurry message, tidying up:
The question is: Why does it write faster than it reads? Only small
files are read faster than they are written. This hasn't happened to
me before... Though performance seems high to me, should it be
higher?
SYSTEM:
Mandrake 7.0 running kernel 2.2.14
1*PIII-600Mhz Coppermine, 384Mb RAM, Mylex ExtremeRAID
1100 w/64Mb cache. 8x50Gb Seagate Barracuda (7200 RPM). I've
placed 4 disks on two of the channels on the controller.
The Mylex controller has firmware 5-07-0-79.
Running RAID 0, one 380Gb partition with "mke2fs -b 4096 -i 16384
-m 1 -s 1 -R stride=16"
The partition has to be that big because of our production software.
Here are some Tiotest (0.24) results:
4 threads, 200Mb files:
Tiotest results for 4 concurrent io threads:
----------------------------------------------------------------------.
| Item |
Time | Rate | User CPU | System CPU |
+------------------+--
---------+--------------+-----------+------------+
|
800 MBs write | 14.0 s | 57.168 MB/s | 1.5 % | 45.4 % |
|
800 MBs read | 23.4 s | 34.216 MB/s | 0.5 % | 14.4 %
|
| 4000 Seeks | 4.5 s | 879.9 s/s | 0.2 % | 2.9 %
|
----------------------------------------------------------------------'
*************
4 threads, 1024Mb files:
Tiotest results for 4 concurrent io threads:
,-------------------------------
---------------------------------------.
| Item | Time | Rate |
User CPU | System CPU |
+------------------+-----------+--------------+-----
------+------------+
|
4096 MBs write | 76.8 s | 53.345 MB/s | 2.0 % | 41.9 % |
4096 MBs read | 122.2 s | 33.528 MB/s | 0.5 % | 14.2 % |
4000 Seeks | 10.2 s | 393.5 s/s | 0.1 % | 0.9 % |
------
----------------------------------------------------------------'
Kent R. Nilsen
