Søren Schmidt wrote:
On 7Nov, 2008, at 20:12 , Peter Wemm wrote:
On Thu, Nov 6, 2008 at 11:17 PM, Jeremy Chadwick <[EMAIL PROTECTED]>
wrote:
[..]
As stated, FreeBSD's ATA command timeout is hard-set to 5 seconds, and
is not adjustable without editing the ATA code yourself and increasing
the value. The FreeNAS folks have made patches available to turn the
timeout value into a sysctl.
Soren and/or others, please increase this timeout value. Five seconds
has now been deemed too aggressive a default. And please consider
migrating the timeout value into a sysctl.
The 5 second timeout has been a problem for quite a while actually.
I've had a number of instances where I've had to increase it to 20 or
30 seconds when recovering from marginal drives. The longest
"successful" recovery attempt I've seen was 26 seconds, I believe on a
Maxtor drive a few years ago. ("successful" == the drive spent 26
seconds but eventually successfully read the sector). Even the IBM
death star drives could take much longer than 5 seconds to do a
recovery 5 years ago. 5 seconds has never been a good default.
I think the timeout should be increased to at least 30 seconds. My
windows box has a timeout that goes for several minutes.
If there is concern about FreeBSD appearing to hang, I could imagine
that a console warning message could be printed after 5 seconds. But
just say "drive has not yet responded". But give it more time.
In this day and age we're generally not playing games with udma33 vs
66, notched cables, poor CRC support etc. SATA seems to have
eliminated all that. Hmm, it might make sense to increase the timeout
on SATA connections to 2 or 3 minutes by default.
Actually I do have a patch around that logs the timeout on the console
after the normal timeout (5secs), then just goes on to wait for double
the timeout and log again etc etc, final timeout was IIRC 60 secs but
could be anything.
I have a disk which I am finally getting rid of that produces READ_DMA
and WRITE_DMA errors at a pretty high rate. I did enable the extra ATA
error reporting and it doesn't seem to indicate any sort of actual
errors, just extra long itmeouts.
At one time, I did change the system to extend the timeout, but I did
not see any real improvement at 30 seconds. I suspect that an even more
extended timeout would be necessary to solve the problem.
I am removing the disk this week. Does anyone want a disk that produces
DMA timeouts at a regular rate? Would it help actually solve this problem?
Please let me know if you want such a beast and I will ship it to you.
/Joe
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