Hi every-body,
On 2 DS10s EV67 TRU64 V4, i have measured disk accesses using random and
sequential accesses ( a program repeats 1000 reads + write of 32 KB in raw mode ).
I used 2 different EV67 configurations:
- one with 2 IDEs 30 GB 7200 RPM (2 models: 53073W and MPD3108A)
- one with 2 SCSIs 18G / 10000 RPM, using 2 different models (RZ2ED and BD018635C4).
The first results shows the following throughputs ( input + output):
- sequential accesses:
IDE disk drives (both models): 6 MB/s (10.6 ms mean time for read + write)
SCSI 1: 4.3 MB/s (14.8 ms ...)
SCSI 2: 6.5 MB/s (9.8 ms)
- random accesses:
IDE: 4.7 MB/s (13.6 ms)
SCSI 5 MB/s (12.8 ms)
Do you have an idea why the performance goes from
14.8 ms with one SCSI disk drive to 6.5 ms with the other model
( the RPM is the same, the seek time should not be significant with
sequential accesses) ?
I don't know how i can tune some SCSI drive parameters:
interleaving factor (1), usage of disk drive cache in write enabled ?
At what level can i tune the disk drive cache usage mode ?
I'll envoy if someone can give some comments.
Regards,
Eric
PS: i also made some measurements with the LSM V4 (BCL) on mirrored disks,
and with concurrencies on 2 IDE disks on the same channel. They
show for LSM half level of performance, and for IDE disk concurrency
a bad parallelism ( 20 % of gain only).
mailto: eric.chacron_at_alcatel.fr
.
Received on Wed May 30 2001 - 15:07:37 NZST