On Feb 15, 2010, at 8:43 PM, heinz zerbes wrote: > > Gents, > > We want to understand the mechanism of zfs a bit better. > > Q: what is the design/algorithm of zfs in terms of reclaiming unused blocks? > Q: what criteria is there for zfs to start reclaiming blocks
The answer to these questions is too big for an email. Think of ZFS as a very dynamic system with many different factors influencing block allocation. > Issue at hand is an LDOM or zone running in a virtual (thin-provisioned) disk > on a NFS server and a zpool inside that vdisk. > This vdisk tends to grow in size even if the user writes and deletes a file > again. Question is, whether this reclaiming of unused blocks can kick in > earlier, so that the filesystem doesn't grow much more than what is actually > allocated? ZFS is a COW file system, which partly explains what you are seeing. Snapshots, deduplication, and the ZIL complicate the picture. -- richard ZFS storage and performance consulting at http://www.RichardElling.com ZFS training on deduplication, NexentaStor, and NAS performance http://nexenta-atlanta.eventbrite.com (March 15-17, 2010) _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
