On 10/25/2009 02:22 AM, Pavel Machek wrote:
Hi!
So I have been experimenting with various root file systems on my
laptop running latest git. This laptop some times has problems waking
up from sleep and that results in it needing a hard reset and
subsequently unclean file system.
A number of people have reported this, and there is some discussion
and some suggestions that I've made here:
http://bugzilla.kernel.org/show_bug.cgi?id=14354
It's been very frustrating because I have not been able to replicate
it myself; I've been very much looking for someone who is (a) willing
to work with me on this, and perhaps willing to risk running fsck
frequently, perhaps after every single unclean shutdown, and (b) who
can reliably reproduce this problem. On my system, which is a T400
running 9.04 with the latest git kernels, I've not been able to
reproduce it, despite many efforts to try to reproduce it. (i.e.,
suspend the machine and then pull the battery and power; pulling the
battery and power, "echo c> /proc/sysrq-trigger", etc., while
doing "make -j4" when the system is being uncleanly shutdown)
I wonder if we might have better luck if we tested using an external
(e-sata or USB connected) S-ATA drive.
Instead of pulling the drive's data connection, most of these have an
external power source that could be turned off so the drive firmware
won't have a chance to flush the volatile write cache. Note that some
drives automatically write back the cache if they have power and see a
bus disconnect, so hot unplugging just the e-sata or usb cable does not
do the trick.
Given the number of cheap external drives, this should be easy to test
at home....
Do they support barriers?
(Anyway, you may want to use some kind of VM for testing. That should
make the testing cycle shorter, easier to reprorduce *and* more repeatable.)
Pavel
The drives themselves will support barriers - they are the same S-ATA/ATA drives
you get normally for your desktop, etc.
I think that e-SATA would have no trouble (but fewer boxes have that external
S-ATA port). Not sure how reliable the SCSI -> USB -> ATA conversion is for USB
drives though (a lot of moving pieces there!).
VM testing is a good idea, but I worry that the virtual IO stack support for
data integrity is still somewhat shaky. Christoph was working on fixing various
bits and pieces I think...
ric
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