Question,
I currently have a 965 chipset-based motherboard, use 4 port onboard and
several PCI-e x1 controller cards for a raid 5 of 10 raptor drives. I get
pretty decent speeds:
user@host$ time dd if=/dev/zero of=100gb bs=1M count=102400
102400+0 records in
102400+0 records out
107374182400 bytes (107 GB) copied, 247.134 seconds, 434 MB/s
real 4m7.164s
user 0m0.223s
sys 3m3.505s
user@host$ time dd if=100gb of=/dev/null bs=1M count=102400
102400+0 records in
102400+0 records out
107374182400 bytes (107 GB) copied, 172.588 seconds, 622 MB/s
real 2m52.631s
user 0m0.212s
sys 1m50.905s
user@host$
Also, when I run simultaenous dd's from all of the drives, I see
850-860MB/s, I am curious if there is some kind of limitation with
software raid as to why I am not getting better than 500MB/s for
sequential write speed? With 7 disks, I got about the same speed, adding
3 more for a total of 10 did not seem to help in regards to write.
However, read improved to 622MBs/ from about 420-430MB/s.
However, if I want to upgrade to more than 12 disks, I am out of PCI-e
slots, so I was wondering, does anyone on this list run a 16 port Areca or
3ware card and use it for JBOD? What kind of performance do you see when
using mdadm with such a card? Or if anyone uses mdadm with less than a 16
port card, I'd like to hear what kind of experiences you have seen with
that type of configuration.
Justin.
-
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
