[Pvfs2-users] corrupted output

Chris Poultney crispy at cs.nyu.edu
Tue Dec 14 17:40:19 EST 2010


Should have mentioned:

pvfs 2.8.2
Ubuntu 10.04, kernel 2.6.32-25-server, using kernel module

Using two patches from Kevin Harms regarding Berkeley DB and multiple 
filesystem entries in /etc/pvfs2-fs.conf (I believe these have since 
been committed to HEAD).

-crispy


On 12/14/2010 05:29 PM, Chris Poultney wrote:
> All-
>
> I'm having a problem where files written to a PVFS volume overwrite the
> beginning of the file after some output has already been generated, as
> if lseek() had been called mid-write. The overwriting behavior does not
> show up on a regular ext3 volume. Sample code is attached. I'd like to
> know if anyone can duplicate this behavior, because it looks like a bug.
>
> Essentially what happens is this: given a large (1024+ character)
> string, I write some portion of the string using a C++ ostream, then
> write another line:
>
> out << st.substr(0, N);
> out << "done";
>
> If N < 1024, everything is fine. If N >= 1024, "done" is written at the
> beginning of the file, overwriting what was there before.
>
> I'd love to figure this out!
>
> Cheers,
> -crispy
>
>
>
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