dd if=/dev/zero of=bigfile bs=1m count=1000
[...]
1048576000 bytes transferred in 11.907 secs (88063828 bytes/sec)
[...]
mfi0 at pci1 dev 0 function 0: SAS 9260-8i
mfi0: interrupting at ioapic0 pin 18
mfi0: logical drives 3, version 12.12.0-0111, 512MB RAM
Compared to the adapter RAM, this is not a large write. As long as
it fits into the cache (provided that the battery is OK), I'm
getting with an identical adapter, and also 6.0_BETA2:
# dd if=/dev/zero of=/mnt/bigfile bs=1m count=300
[...]
314572800 bytes transferred in 0.604 secs (520815894 bytes/sec)
Hm, I'm envious, I only get 128MB/s in an identical test.
Anyway, I re-did the test with mor data, and essentially got the
same result:
20971520000 bytes transferred in 240.888 secs (87059214 bytes/sec)
This is with two 1T SATA2 disks in a RAID1 configuration.
Now, I have a couple other logical units in this box, among them
a pair of SATA2 SSDs, also in a RAID1 configuration, but the
performance is most disappointing:
10485760000 bytes transferred in 128.566 secs (81559354 bytes/sec)
I.e. *slower* than the rotating 1TB disks -- it had a sprint at
the very start where it peaked at around 192MB/s according to
"systat vm", but it quickly settled at around 80MB/s.
The SAS performance is really disappointing. Perhaps OpenBSD
known which knob to turn to get more out of it. Raw handshake
and DMA performance don't seem to be the limitation.
I think there must be more than just SAS vs. SATA which is the
problem here. I think there must be something fishy with the
driver (say I without having taken a closer look at it).
A third logical unit in the box has been mistakenly configured as
a raid6 (it should have been raid10, something I'll be fixing),
and there I get
1048576000 bytes transferred in 32.567 secs (32197500 bytes/sec)
Not much to cheer about that either.
Regards,
- Håvard