Derek Taubert wrote:
On Tue, Aug 29, 2006 at 10:27:26PM +0900, Tejun Heo wrote:
2) hdparm -C for all 4 drives always shows "drive state is: standby"
even when I'm certain that the drives are active.
hdparm -C says the same thing for my drive. I think it's safe to
ignore. Hmmm... it needs to be tracked down. Maybe some problem in
HDIO ioctl implementation in libata.
It's a "nice to have" for using smartd. ie: don't spin the drives up to
poll the failure attributes, but they should be checked if the drive's
already active.
I don't really understand what you mean. Can you elaborate?
Sure. See the "-n standby" option here:
http://smartmontools.sourceforge.net/man/smartd.conf.5.html
If the driver always reports "standby", then smartd effectively won't
monitor the device if "-n standby" is configured.
Now I can certainly eliminate the -n option from smartd.conf, but
then smartd will cause the drive(s) to spin up when it polls (see the
-p, -u, -t options).
Ah.. I see. I'll try to track down that ioctl problem.
I'd really like some assistance debugging the write performance issue.
The "hdparm -C" issue would be gravy...
Please track down the reader.
Before running dd (fuser -v /dev/sda1 shows nothing):
[--snip--]
Can you try 'dd if=/dev/zero of=/dev/sdX bs=4M count=1'?
Increasing the block size eliminates the reads (presumably because the
block driver doesn't have to fetch lines to read/modify/write),
That's actually page cache trying to fill the rest of the page.
> but the write throughput is still very slow:
# dd if=/dev/zero of=/dev/sda1 bs=4M count=512
avg-cpu: %user %nice %sys %iowait %idle
0.90 0.00 1.30 97.80 0.00
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sda 15.00 0.00 1920.00 0 19200
Hmm... this really is weird. FYI, you're the first to report such
problem. As Jeff said, turning off write-back caching can have adverse
effect on write performance, but, then again, you previously reported
that the command queue is full. Please update us on the write-back stuff.
Thanks.
--
tejun
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