On Fri, Nov 12, 2010 at 16:17, chris (fool) mccraw <gently@gmail.com> wrote: > interestingly the default snapshot chunk size on my system: > > LVM version: 2.02.56(1)-RHEL5 (2010-04-22) > Library version: 1.02.39-RHEL5 (2010-04-22) > Driver version: 4.11.5 > > is 4k. a tutorial i was reading suggested it was 64k, and i didn't > doublecheck if that was true. i am going to have to wait til after > business hours to run more thorough tests, but i still see a slowdown > way over 10x even at 64k chunk size with a single snapshot. i'll try > it at all the different available chunk sizes and report back by > monday. Well, I only made it through most chunk sizes. here were my results: (previously obtained: no snapshot = ~11sec (727MB/sec) 1 snapshot @4k chunks = ~102sec (78MB/sec) ) newly obtained: 1 snapshot @16k chunks = ~639sec (12MB/sec) 1 snapshot @32k chunks = ~367sec (21MB/sec) 1 snapshot @64k chunks = ~252sec (31MB/sec) 1 snapshot @256k chunks = ~145sec (55MB/sec) 1 snapshot @512k chunks = ~100sec (80MB/sec) wish i'd tried 8kb, since that's the most interesting area of the graph now that i lay the numbers out together. but no matter what size i use, it's still nearly a factor of 10, and my numbers with the default 4k chunks were almost as good as it gets. _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
