On 03 January, 2007 - Robert Milkowski sent me these 3,0K bytes: > Hello Tomas, > > Wednesday, January 3, 2007, 10:32:39 AM, you wrote: > > TÖ> The tweaks I have are: > TÖ> set ncsize = 500000 > TÖ> set nfs:nrnode = 50 > TÖ> set zfs:zil_disable=1 > TÖ> set zfs:zfs_vdev_cache_bshift=14 > TÖ> set zfs:zfs_vdev_cache_size=0 > > Comment out ncsize and reboot - should help. > I had similar behavior with increased ncsize from default on ZFS+NFS. > Mark suggested to comment it out and it just works since then. > > I was also told increasing ncsize with ZFS isn't needed that much (if > at all) - however I haven't done any testing and I don't know > technical details how DNLC is used with ZFS to be sure.
The thing is, I want DNLC-like cache Very Much.. There are rsync's running against large trees all the time and if we can save on disk io there, it's a Big Win.. df (GNU df) says there are ~850k inodes used, I'd like to keep those in memory.. There is currently 1.8TB used on the filesystem.. The probability of a cache hit in the user data cache is about 0% and the probability that an rsync happens again shortly is about 100%.. So I'd like to get rid of just about all data caching and just do metadata caching instead.. That's why I turned off the vdev cache for instance, cache is evicted before it's used again.. According to Sanjeev Bagewadi @sun.com: >But in the ZFS world, DNLC is part of the ARC, right? > > Not really... ZFS uses the regular DNLC for lookup optimization. However, the metadata/data is cached in the ARC. --snip-- It's interesting though that dnlc_nentries says it's lowered to its minimum @ 15k entires and arc::print has lowered it's "c" to "c_min" (which is 64MB).. So memory is definately going elsewhere.. I can try lowering ncsize, but that is just about the opposite of what I want. I tried changing arc_reduce_dnlc_percent=0 to keep my dnlc cache and let someone else free their memory instead, but that lead to death much faster.. Adding more memory seem to just give you more time, not solve the problem.. /Tomas -- Tomas Ögren, [EMAIL PROTECTED], 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
