On Jan 7, 2012, at 8:59 AM, Jim Klimov wrote: > I wonder if it is possible (currently or in the future as an RFE) > to tell ZFS to automatically read-ahead some files and cache them > in RAM and/or L2ARC?
See discussions on the ZFS intelligent prefetch algorithm. I think Ben Rockwood's description is the best general description: http://www.cuddletech.com/blog/pivot/entry.php?id=1040 And a more engineer-focused description is at: http://www.solarisinternals.com/wiki/index.php/ZFS_Performance#Intelligent_prefetch -- richard > > One use-case would be for Home-NAS setups where multimedia (video > files or catalogs of images/music) are viewed form a ZFS box. For > example, if a user wants to watch a film, or listen to a playlist > of MP3's, or push photos to a wall display (photo frame, etc.), > the storage box "should" read-ahead all required data from HDDs > and save it in ARC/L2ARC. Then the HDDs can spin down for hours > while the pre-fetched gigabytes of data are used by consumers > from the cache. End-users get peace, quiet and less electricity > used while they enjoy their multimedia entertainment ;) > > Is it possible? If not, how hard would it be to implement? > > In terms of scripting, would it suffice to detect reads (i.e. > with DTrace) and read the files to /dev/null to get them cached > along with all required metadata (so that mechanical HDDs are > not required for reads afterwards)? > > Thanks, > //Jim Klimov > _______________________________________________ > zfs-discuss mailing list > email@example.com > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss -- ZFS and performance consulting http://www.RichardElling.com illumos meetup, Jan 10, 2012, Menlo Park, CA http://www.meetup.com/illumos-User-Group/events/41665962/ _______________________________________________ zfs-discuss mailing list firstname.lastname@example.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss