Hi, With read-ahead 'option page-size 16kB' you may not achieve maximum throughput, so, better try 'option page-size 128kB' (Note that 16K is just treated as 16bytes, as the parser needs 'KB' 'MB' 'GB' as the unit, not K, M, or G respectively). Regards, Amar On Dec 21, 2007 3:20 PM, Grigory Shamov <gas@xxxxxx> wrote: > Dear Sam, > > Thank you for the quick reply. > > Sam Douglas ?????: > > As I understand it, read and write calls in GlusterFS (and FUSE) are > > done with supplied offsets (for example read 8192 bytes at position > > 9024 of the file). This is why seek performance is pretty consistent. > > The rewrite performance with read-ahead and write-behind drops because > > writing to the file changes the modification time and invalidates the > > read-ahead cache. Thus the data that was read was copied needlessly. > > So, is there a way to tune it somehow? For now I couldn't think of > anything except using very small values for the read-ahead cache. With > page-size of 16K and page-count 1 I get Rewrite of about 7000 K/sec but > the Sequential Read only about 26000 K/sec which is only a half of the > best possible value. > > -- > WBR, Grigory Shamov > > > > > > > Sam Douglas > > > > On Dec 19, 2007 10:56 PM, Grigory Shamov <gas@xxxxxx> wrote: > >> Dear GlusterFS developers, > >> > >> So I did a Bonnie++ benchmark using one of the servers (Dual Opteron, > >> 4GB RAM, SATA disk, CentOS Linux 5) and a client (old P4 2.4GHz box, > >> 512MB RAM, Gigabit Ethernet, CentOS 4.5). I used 8Gb size for the > >> Bonnie++ tests, and tried either forced flush IO or not (-b option; the > >> data below are for the latter case). Some of the Bonnie++ results are > >> like this: > >> > >> =============================================== > >> FileSystem: Sequential Output , K/sec > >> Per-char Block Rewrite > >> =============================================== > >> NFS 14442 30419 7710 > >> Lustre 16012 35228 19018 > >> GlusterFS 16582 15833 8358 > >> GlusterFS, wb 17988 43774 8409 > >> GlusterFS, ra 18414 15863 1804 > >> GlusterFS, ra, wb 22403 41821 355 > >> =============================================== > >> FileSystem: Sequential Input, K/sec Random > >> Per-char Block seeks, #/s > >> =============================================== > >> NFS 20229 49510 178.8 > >> Lustre 17284 47753 53.0 > >> GlusterFS 16791 16815 161.4 > >> GlusterFS, wb 15304 17438 174.1 > >> GlusterFS, ra 19420 54803 143.3 > >> GlusterFS, ra, wb 19900 54427 144.4 > >> =============================================== > > > > _______________________________________________ > Gluster-devel mailing list > Gluster-devel@xxxxxxxxxx > http://lists.nongnu.org/mailman/listinfo/gluster-devel > -- Amar Tumballi Gluster/GlusterFS Hacker [bulde on #gluster/irc.gnu.org] http://www.zresearch.com - Commoditizing Supercomputing and Superstorage!
