Re: CephFS Space Accounting and Quotas

["Jim Schutt" <jaschut@sandia.gov>]

On 03/11/2013 02:40 PM, Jim Schutt wrote:
>>> >> If you want I can attempt to duplicate my memory of the first
>>> >> test I reported, writing the files today and doing the strace
>>> >> tomorrow (with timestamps, this time).
>>> >>
>>> >> Also, would it be helpful to write the files with minimal logging, in
>>> >> hopes of inducing minimal timing changes, then upping the logging
>>> >> for the stat phase?
>> > 
>> > Well that would give us better odds of not introducing failures of
>> > any kind during the write phase, and then getting accurate
>> > information on what's happening during the stats, so it probably
>> > would. Basically I'd like as much logging as possible without
>> > changing the states they system goes through. ;)
> Hmmm, this is getting more interesting...
> 
> I just did two complete trials where I built a file system,
> did two sets of writes with minimal MDS logging, then 
> turned MDS logging up to 20 with MDS ms logging at 1 for
> the stat phase.
> 
> In each trial my strace'd find finished in < 10 seconds,
> and there were no slow stat calls (they were taking ~19 ms
> each).
> 
> I'm going to do a third trial where I let things rest
> overnight, after I write the files.  That delay is the
> only thing I haven't reproduced from my first trial....

As you suspected, that didn't make any difference either...
That trial didn't reproduce the slow stat behavior.

It turns out that the only way I can reliably reproduce
the slow stat behavior right now is to turn MDS debugging
up to 20.

I've got another set of logs with MDS debug ms = 1,
which I'll send via an off-list email.

I still haven't figured out what made that first test
exhibit this behavior, when I was using debug mds = 5.

-- Jim

> 
> -- Jim
> 
>