Matthew Ahrens writes: > This case adds capability to ZFS to use storage devices as a level 2 ARC > (L2ARC), caching read requests that would otherwise be satisfied by disk. > Random read performance can then be improved by adding fast storage > devices to the L2ARC, such as short-stroked disks, solid state disks, > and other media with substantially faster read latency than disk.
Is there any way to determine whether a given cache device is helping or hurting me? Perhaps some statistics that can be viewed? Any rule of thumb about choosing such a device? How much faster than main storage does it need to be in order to be useful, and does the organization of main storage make a difference? (E.g., will I get a bigger bang for the buck if I add cache to RAIDZ than to mirroring?) -- James Carlson, Solaris Networking <james.d.carlson at sun.com> Sun Microsystems / 35 Network Drive 71.232W Vox +1 781 442 2084 MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677
