Re: [Moosefs-users] fs_writechunk returns status 11

[Brent A N. <br...@ph...>]

On Fri, 30 Mar 2012, Michał Borychowski wrote:

> Hi!
>
> Error 11 means "chunk locked". It appears when several processes at
> different computers try to write to the same file in parallel.

Huh, I don't see a reason any other machines or even different mfsmounts 
on the same machine would have written to my google-chrome cache files at 
the same time.  I'm only running google-chrome on one machine (indeed, it 
prevents me from starting another instance accidentally on a different 
machine at the same time, and I checked through all of our computers for 
stray processes).

I do have a cron job running on a different machine to purge old cache 
files, although I think that was added after my last errors.  Would a file 
deletion even lock a chunk for writing, or would that be purely a metadata 
operation? How about an atime update (I would think that would have to be 
a metadata server operation and would not involve the chunks in any way)?

Could the servers, in their internal maintenance schedule, be briefly 
locking the chunks for other reasons?

I still wonder if Chrome might be tickling some corner case every now 
and then and producing these messages with the involvement of just one 
mfsmount...

> You should not be bothered by this message but it's wise to minimize 
> occurrences of this situation.

Indeed, I've observed no problems resulting from this warning, apart from 
it generating enough complaints to fill a 1.2GB /var after awhile.  When 
it happens, it happens in large bursts.  By the way, so far, I've seen no 
further warnings since disabling the google-chrome cache (which seems much 
faster, anyway).  So far, so good.

Thanks,

Brent