On Sun, Oct 26, 2014 at 12:26:57PM -0500, Stan Hoeppner wrote: > > > On 10/26/2014 09:26 AM, Brian Foster wrote: > > On Sat, Oct 25, 2014 at 04:26:54PM -0500, Stan Hoeppner wrote: > >> On 10/25/2014 01:56 PM, Richard Scobie wrote: > >>> Stan Hoeppner said: > >>> > >>>> How can I disable or change the filestreams behavior so all files go > >>>> into the one AG for the single directory test? > >>> > >>> Hi Stan, > >>> > >>> Instead of mounting with -o filestreams, would using the chattr flag > >>> instead help? > >>> > >>> See > >>> http://xfs.org/docs/xfsdocs-xml-dev/XFS_User_Guide/tmp/en-US/html/ch06s16.html > >> > >> That won't help. That turns it on (if it's not enabled by default these > >> days). I need to turn off the behavior I'm seeing, whether it's due to > >> the filestreams allocator or default inode64. Then again it may not be > >> possible to turn it off... > >> > >> Anyone have other ideas on how to accomplish my goal? Parallel writes > >> to a single AG on the outer platter edge vs the same to all AGs across > >> the entire platter? I'm simply trying to demonstrate the differences in > >> aggregate bandwidth due to the extra seek latency of all AGs case. > >> > > > > What about just preallocating the files? Obviously this removes block > > allocation contention from your experiment, but it's not clear if that's > > relevant to your test. If I create a smaller, but analogous fs to yours, > > I seem to get this behavior from just doing an fallocate of each file in > > advance. > > > > E.g., Create directory 0, fallocate 44 files all of which end up in AG > > 0. Create directory 1, fallocate 44 files which end up in AG 1, etc. > > From there you can do direct I/O overwrites to 44 files across each AG > > or 44 files in any single AG. > > I figured preallocating would get me what I want but I've never used > fallocate, nor dd into fallocated files. Is there anything special > required here with dd, or can I simply specify the filename to dd, and > make sure bs + count doesn't go beyond EOF? > Ah, yeah. dd will truncate the file by default iirc, which would free the preallocated blocks and start from scratch. Specify 'conv=notrunc' as part of the command line to get around that. Brian > Thanks, > Stan > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
