Ingo Molnar wrote:
>
> could you send me your /etc/raidtab? I've tested the performance of 4-disk
> RAID0 on SCSI, and it scales perfectly here, as far as hdparm -t goes.
> (could you also send the 'hdparm -t /dev/md0' results, do you see a
> degradation in those numbers as well?)
>
> it could either be some special thing in your setup, or an IDE+RAID
> performance problem.
>
> Ingo
Im not sure how usefull these results are, the number seemed to vary by
1MB/s or so between runs, and i do have 128MB ram. Im not sure if hdparm
is sensitive to ramsize.
So generally, a 50% increase for a second drive, and then no increase
after that.
I am glad to hear that scsi scales well, at least that limits to
problems to ide or me doing something silly.
Maybe i should try on a different motherboard.....
4-way raid0 (/dev/hde, /dev/hdg, /dev/hdi, /dev/hdk)
/dev/md0:
Timing buffer-cache reads: 128 MB in 1.67 seconds = 76.65 MB/sec
Timing buffered disk reads: 64 MB in 2.09 seconds = 30.62 MB/sec
3-way raid0 (/dev/hde, /dev/hdg, /dev/hdi)
/dev/md0:
Timing buffer-cache reads: 128 MB in 1.59 seconds = 80.50 MB/sec
Timing buffered disk reads: 64 MB in 2.15 seconds = 29.77 MB/sec
2-way raid0 (/dev/hde, /dev/hdg)
/dev/md0:
Timing buffer-cache reads: 128 MB in 1.59 seconds = 80.50 MB/sec
Timing buffered disk reads: 64 MB in 1.94 seconds = 32.99 MB/sec
Im used a 32K chunk size for all the tests i did, here is my raidtab
To change the number of drives i was testing i just changed
nr-raid-disks and uncommented the next disks, i didnt touch anything
else.
raiddev /dev/md0
raid-level 0
persistent-superblock 1
chunk-size 32
nr-raid-disks 2
nr-spare-disks 0
device /dev/hde5
raid-disk 0
device /dev/hdg5
raid-disk 1
# device /dev/hdi5
# raid-disk 2
# device /dev/hdk5
# raid-disk 3
Thanks
Glenn
