> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
> boun...@opensolaris.org] On Behalf Of Richard Elling
> For example, does 'zfs send -D' use the same DDT as the pool?
> No.
> Or does it require more memory for it's own DDT, thus impacting
> performance of both?
> Yes, no.

How can this be?  
If zfs send -D does not use the same DDT as the pool, then it must require
memory for its own DDT.  But Richard, the second half of your answer seems
to contradict this.  Perhaps you are denying that the extra memory usage
impacts performance of the system?

> If you have a deduped pool on both ends of the send, does -D make any
> difference?
> If neither pool is deduped, does -D make a difference?

Yes.  If the originating pool is dedup'd on disk, then it's just dedup'd on
disk.  And if the recipient pool is dedup'd on disk, then it's just dedup'd
on disk.  In either case, traditionally the data would not be dedup'd in
transit (zfs send.)

zfs send -D only causes the data to be dedup'd in the data stream from the
sender to the receiver.  This presumably saves network bandwidth and
accelerates the network traffic.

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