Re: SRPT and SCST

[Vladislav Bolkhovitin <vst-d+Crzxg7Rs0@public.gmane.org>]

Bart Van Assche, on 11/06/2009 10:06 AM wrote:
> On Fri, Nov 6, 2009 at 3:54 AM, Philip Pokorny
> <ppokorny-pabcTyWEv4ZW60MLeMDbCVaTQe2KTcn/@public.gmane.org> wrote:
>> ======= Update
>> At Chris's suggestion, I changed the scst threading to a *single* thread.  I
>> also changed the number of outstanding commands to 32 (from 64)  We have a
>> relatively large number of initiators (50, currently testing with only 4)
>> but each initiator has it's own dedicated, non-shared set of LVM "block"
>> devices.  So it does not seem necessary to set the device queue size to
>> initiators*device_queue_size.  I set the total device queued commands to 37.
>>
>> Re-running the test, the storage is "stable" and completed the first phase
>> of the test (create and check the filesystem) but now two of four clients
>> have "live-locked" waiting for an I/O to complete for the last 15 minutes or
>> so.
>>
>> On the initiators iostat looks like this:
>>
>> Device:         rrqm/s   wrqm/s   r/s   w/s    rkB/s    wkB/s avgrq-sz
>> avgqu-sz   await  svctm  %util
>> sdb               0.00     0.00  0.00  0.00     0.00     0.00     0.00
>> 160.02    0.00   0.00 100.01
>> sdb               0.00     0.00  0.00  0.00     0.00     0.00     0.00
>> 160.02    0.00   0.00 100.01
>> sdb               0.00     0.00  0.00  0.00     0.00     0.00     0.00
>> 160.02    0.00   0.00 100.01
>> sdb               0.00     0.00  0.00  0.14     0.00     8.14   114.00
>> 159.34 180114.00 7002.00 100.03
>> sdb               0.00     0.00  0.00  0.00     0.00     0.00     0.00
>> 160.02    0.00   0.00 100.01
>> sdb               0.00     0.00  0.00  0.00     0.00     0.00     0.00
>> 160.02    0.00   0.00 100.01
>>
>> This tells me that there is a pending I/O waiting to be completed but it
>> seems to have been lost on the server, because this is taking much too
>> long.  There are 7 seconds "between" each line of output above so that's
>> almost 30 seconds of output with *no* change in the I/O status.
>>
>> The "gzip | tar -x" I was running is "hung"
> 
> Hello Phil,
> 
> Can you please post the SCST target logs available for the above scenario ?

Yes, and please make sure you are running the debug build.

> Bart.
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