Jeremy Chadwick wrote: > Well, my understanding (which is probably wrong) is that the memory > used for the ARC is somehow separate from that of the kmap. I was > under the impression the kmap was used by ZFS for other things, and > did not include ARC.
kmem is used by ARC. You can check your total kmem usage by ZFS using 'vmstat -m' under the line that says 'solaris'. > People have advocated increasing arc_min and arc_max in the past, citing > large performance gains as arc_max gets larger; you might see people > mentioning that they see great performance increases when increasing > arc_max from 64M to 128M. My understanding is that increasing the ARC > provides more actual cached data that ZFS can reference (vs. pulling it > off disk). Again, if I'm incorrect, please state so. You are correct about the benefits of increasing arc_max. I don't know of any benefits of tuning arc_min. Maybe someone else can answer this. By default on 7-STABLE arc_max will be 3/4 of kmem_size. So if you are using 1536M for kmem_size, arc_max will be 1152M by default. But some people will maybe need to lower it to avoid panic during heavy I/O since in those scenarios ARC cache size could for short periods of time be larger than arc_max and reach kmem limit. _______________________________________________ freebsd-hardware@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hardware To unsubscribe, send any mail to "[EMAIL PROTECTED]"