On Jan 30, 2011, at 2:29 PM, Richard Elling wrote: > On Jan 30, 2011, at 12:21 PM, stuart anderson wrote: > >> Is it possible to partition the global setting for the maximum ARC size >> with finer grained controls? Ideally, I would like to do this on a per >> zvol basis but a setting per zpool would be interesting as well? > > While perhaps not perfect, see the primarycache and secondarycache > properties of the zvol or file system.
With primarycache I can turn off utilization of the ARC for some zvol's, but instead I was hoping to use the ARC but limit the maximum amount on a per zvol basis. > >> The use case is to prioritize which zvol devices should be fully cached >> in DRAM on a server that cannot fit them all in memory. > > It is not clear to me that this will make sense in a world of snapshots and > dedup. > Could you explain your requirements in more detail? I am using zvol's to hold the metadata for another filesystem (SAM-QFS). In some circumstances I can fit enough of this into the ARC that virtually all metadata reads IOPS happen at DRAM performance rather than SSD or slower. However, with a single server hosting multiple filesystem (hence multiple zvols) I would like to be able to prioritize the use of the ARC. P.S. Since SAM-QFS metadata is highly compressible, O(10x), it would also be great if there was an option to cache the compressed blocks in DRAM (and not just the decompressed version). Thanks. -- Stuart Anderson ander...@ligo.caltech.edu http://www.ligo.caltech.edu/~anderson _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
