Hi Chris, This looks like it might be an issue with writev in the kernel. Are you running RHEL5 by chance? -sam
On Dec 15, 2010, at 8:39 AM, Chris Poultney wrote: > Sure - it's attached. I ran exactly the code I posted earlier. > > -crispy > > > On 12/14/2010 07:25 PM, Sam Lang wrote: >> >> Hi Chris, >> >> Would you be willing to run your test with strace and post the output? That >> will help us figure out what read/write system calls PVFS is getting from >> your app. >> >> Thanks, >> -sam >> >> On Dec 14, 2010, at 4:29 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 >>> >>> <pvfstest.cpp>_______________________________________________ >>> Pvfs2-users mailing list >>> [email protected] >>> http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users >> > <strace.out> _______________________________________________ Pvfs2-users mailing list [email protected] http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users
