On 21 December, 2009 - Tristan Ball sent me these 4,5K bytes: > Richard Elling wrote: > > > > On Dec 20, 2009, at 12:25 PM, Tristan Ball wrote: > > > >> I've got an opensolaris snv_118 machine that does nothing except > >> serve up NFS and ISCSI. > >> > >> The machine has 8G of ram, and I've got an 80G SSD as L2ARC. > >> The ARC on this machine is currently sitting at around 2G, the kernel > >> is using around 5G, and I've got about 1G free. ... > What I'm trying to find out is is my ARC relatively small because... > > 1) ZFS has decided that that's all it needs (the workload is fairly > random), and that adding more wont gain me anything.. > 2) The system is using so much ram for tracking the L2ARC, that the ARC > is being shrunk (we've got an 8K record size) > 3) There's some other memory pressure on the system that I'm not aware > of that is periodically chewing up then freeing the ram. > 4) There's some other memory management feature that's insisting on that > 1G free.
My bet is on #4 ... http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/fs/zfs/arc.c#arc_reclaim_needed See line 1956 .. I tried some tuning on a pure nfs server (although s10u8) here, and got it to use a bit more of "the last 1GB" out of 8G.. I think it was swapfs_minfree that I poked with a sharp stick. No idea if anything else that relies on it could break, but the machine has been fine for a few weeks here now and using more memory for ARC.. ;) /Tomas -- Tomas Ögren, st...@acc.umu.se, http://www.acc.umu.se/~stric/ |- Student at Computing Science, University of Umeå `- Sysadmin at {cs,acc}.umu.se _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
