Steve Polyack
2010-Feb-12 18:31 UTC
ZFS ARC being limited below what is defined in /boot/loader.conf
Has anyone had an issue with the ZFS ARC max being limited below what has been defined in /boot/loader.conf? I just upgraded the RAM in a ZFS-equipped system and attempted to devote 4GB to the ARC cache by placing the following in loader.conf: vfs.zfs.arc_max="4096M" However, after rebooting, querying the sysctl gives me this: $ sysctl vfs.zfs.arc_max vfs.zfs.arc_max: 1726489600 or about 1.7GB, an odd number that I can't find any references to. For reference, I'm running 8-STABLE (as of Jan 19th) on an amd64 system with 8GB of RAM. The system was previously very stable with 4GB of RAM and a 512MB arc_max. I have not modified vm.kmem_size_max (defaults to ~330GB on amd64) or any other ZFS tunables. I'd also like to avoid syncing up to the current 8-STABLE if at all possible. Thanks, Steve Polyack
Artem Belevich
2010-Feb-12 18:47 UTC
ZFS ARC being limited below what is defined in /boot/loader.conf
Check your vm.kmem_size. Default setting is way too low. Set it to at least double of desired arc size. --Artem On Fri, Feb 12, 2010 at 10:31 AM, Steve Polyack <korvus@comcast.net> wrote:> Has anyone had an issue with the ZFS ARC max being limited below what has > been defined in /boot/loader.conf? ?I just upgraded the RAM in a > ZFS-equipped system and attempted to devote 4GB to the ARC cache by placing > the following in loader.conf: > ?vfs.zfs.arc_max="4096M" > > However, after rebooting, querying the sysctl gives me this: > $ sysctl vfs.zfs.arc_max > vfs.zfs.arc_max: 1726489600 > > or about 1.7GB, an odd number that I can't find any references to. ?For > reference, I'm running 8-STABLE (as of Jan 19th) on an amd64 system with 8GB > of RAM. ?The system was previously very stable with 4GB of RAM and a 512MB > arc_max. ?I have not modified vm.kmem_size_max (defaults to ~330GB on amd64) > or any other ZFS tunables. ?I'd also like to avoid syncing up to the current > 8-STABLE if at all possible. > > Thanks, > Steve Polyack > > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" >