Ricardo M. Correia wrote: > > On Qui, 2008-02-07 at 12:48 -0800, Matthew Ahrens wrote: >> First, note that the problem is quite constrained: >> >> There are a fixed number of attribute names (for any given software version) >> since these are interpreted system attributes. Therefore the attribute names >> can be a small number, rather than a string -- ie, we have an enum that >> defines the attributes. We (ie, OpenSolaris) can control the allocation of >> new enum values in this namespace. > > Since we are on the subject of redesigning attributes, have you > considered providing a lighter-weight extended attribute mechanism to > userspace applications such as Beagle ( > http://beagle-project.org/Enabling_Extended_Attributes > <http://beagle-project.org/Enabling_Extended_Attributes)?> ), Meta > Tracker ( http://www.gnome.org/projects/tracker/ ), Apache (mime types), > etc? > > It seems to me that the usefulness of extended attributes is to > efficiently store small amounts of information associated with a file, > and I think these would make more sense to be in the dnode (possibly > making it 1K by default) or in a single external object if it doesn't > fit into the dnode.
I believe when a prototype using 1K dnodes was tested it showed an unacceptable (30%?) hit on some benchmarks. So if can possibly avoid increasing the dnode size (by default) then we should do so. > > There's a de-facto namespace standard for EAs that specifies some > existing and proposed attributes that could give you some ideas about > this: http://freedesktop.org/wiki/CommonExtendedAttributes > > Of course, this would still require storing the EA names in the dnode, > but I think the added flexibility of being able to efficiently store > arbitrary EAs would be worth it. > And also, the large dnodes feature that we have are working on makes it > rather easy to create filesystems with bigger dnodes. > > Thanks, > Ricardo > -- > *Ricardo Manuel Correia* > Lustre Engineering > > *Sun Microsystems, Inc.* > Portugal > Phone +351.214134023 / x58723 > Mobile +351.912590825 > Email Ricardo.M.Correia at Sun.COM <mailto:Ricardo.M.Correia at Sun.COM> > > > ------------------------------------------------------------------------ > > _______________________________________________ > zfs-code mailing list > zfs-code at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-code
