Take the 2-minute tour ×  I'm thinking of using ZFS to backups
files to single drives that are going to be kept mostly offline.
Does anyone know if the FreeBSD ZFS implementation still uses
memory if a dedupped pool is exported?  share|improve this
question  1 Answer 1  up vote 2 down vote accepted  Technically
yes, practically no.  A minor amount of RAM will be used to keep
track of the status of the pool, it is not removed from the
kernel's data structure unless the drives are all removed. All
ZFS file systems are unmounted however, so none of the file
system caching (ARC/etc) is used.  share|improve this answer OK,
so to be clearer. If I'm using a 3TB drive I'll assume that if I
turn dedup on for that single drive pool and fill it I'll be
using a couple of GBs of RAM. But if I unmount/export the pool
and remove the drive then FreeBSD will release the memory taken
by that pool's dedup tables? –  Cyclone Sep 14 '12 at 22:35 In
broad strokes, yes. The RAM usage will depend on a lot of
things, but when unmount