G'Day Gray, On Thu, Jan 15, 2009 at 03:36:47PM +0800, Gray Carper wrote: > > Hey, all! > Using iozone (with the sequential read, sequential write, random read, > and random write categories), on a Sun X4240 system running > OpenSolaris b104 (NexentaStor 1.1.2, actually), we recently ran a > number of relative performance tests using a few ZIL and L2ARC > configurations (meant to try and uncover which configuration would be > the best choice). I'd like to share the highlights with you all > (without bogging you down with raw data) to see if anything strikes > you. > Our first (baseline) test used a ZFS pool which had a self-contained > ZIL and L2ARC (i.e. not moved to other devices, the default > configuration). Note that this system had both SSDs and SAS drive > attached to the controller, but only the SAS drives were in use. > In the second test, we rebuilt the ZFS pool with the ZIL on a 32GB SSD > and the L2ARC on four 146GB SAS drives. Random reads were > significantly worse than the baseline, but all other categories were > slightly better. > In the third test, we rebuilt the ZFS pool with the ZIL on a 32GB SSD > and the L2ARC on four 80GB SSDs. Sequential reads were better than the
The L2ARC trickle charges (especially since it feeds from random I/O, which by nature has low throughput), and with 4 x 80GB of it online - you could be looking at an 8 hour warmup, or longer. How long did you run iozone for? Also, the zfs recsize makes a difference for random I/O to the L2ARC - you probably want it set to 8 Kbytes or so, before creating files. ... The L2ARC code shipped with the Sun Storage 7000 has had some performance improvements that aren't in OpenSolaris yet, but will be soon. Brendan -- Brendan Gregg, Sun Microsystems Fishworks. http://blogs.sun.com/brendan _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
