On Wed, Nov 28, 2012 at 10:24:51PM +0100, J. Hannken-Illjes wrote: > > > Flushing is just writing to the log. These writes have sizes between > 512 bytes and the file system block size. Problem is these writes > are not multiples of and are not aligned to file system block size.
Also issues if they aren't 4k aligned - otherwise the disk itself is likely to be doing RMW as well. I must look at how to determine that disks have 4k sectors and to ensure filesystesm have 4k fragments - regardless of the fs size. By the sound of it the log ought to be written in fs frag (or block) sized chunks - even if that means that 'pad' entries get written in order to flush it to disk after a period of inactivity. David -- David Laight: da...@l8s.co.uk