Anyway increasing it to 5K did not help and drives don't seem to be fully utilized. Does the reshape work something like this: - Read about X = (50M / N - 1 / stripe size) stripes from drives and write them to the backup-file - Reshape X stripes one by another sequentially - Reshaping stripe by reading chunks from all drives, calculate Q, writing all chunks back and doing I/O for next stripe only after finishing previous one? So after increasing stripe_cache_size the cache should hold stripes after backing them and so reshaping should not need to read them from drives again? Cant the slow speed be caused by some synchronization issues? How are the stripes read for writing them to backup-file? Is it done one by one, so I/Os for next stripe are issued only after having read the previous stripe completely? Are they issued in maximum parallel way possible? Patrik On Tue, May 15, 2012 at 1:28 PM, NeilBrown <neilb@xxxxxxx> wrote: > On Tue, 15 May 2012 13:16:42 +0200 Patrik Horník <patrik@xxxxxx> wrote: > >> Can I increase it during reshape by echo N > >> /sys/block/mdX/md/stripe_cache_size? > > Yes. > > >> >> How is the size determined? I have only 1027 while having 8 GB system memory... > > Not very well. > > It is set to 256, or the minimum size needed to allow the reshape to proceed > (which means about 4 chunks worth). I should probably add some auto-sizing > but that sort of stuff is hard :-( > > NeilBrown > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
