zfs send -R [PSARC/2007/574 FastTrack timeout 10/10/2007]

[Matthew Ahrens]

Bill Sommerfeld wrote:
> On Wed, 2007-10-03 at 10:24 -0700, Matthew Ahrens wrote:
>> Note, to receive any of these new type of "zfs send" streams, the
>> receiving system must be running a software version capable of sending
>> them.  Ie, the stream version is incremented.  However, no on-disk
>> changes are required, so these streams can be received into old-version
>> pools.  There are no changes needed to the user interface for "zfs recv"
>> to receive these streams.
> 
> Q1: with respect to this stream version change alone, can an old "zfs
> send" stream still be received by new software?

Yes.

> Q2: with the changes proposed by this case, is a "zfs send" not using
> the new features sent using the older stream version or the newer
> version?

The older version.

> This is motivated by an operational question: I run a couple servers
> which have large zfs pools and which track nevada closely.  Another
> group, which has a server running an s10 update, wants to do backups for
> disaster recovery to one of my servers.  zfs replication of a small
> number of filesystems would be the way to do it but for the current lack
> of commitment to the stream format.

Yep, this should just work.  Despite our lack of commitment, it's our goal for 
new software versions to always be able to receive old streams.  However, at 
some point "zfs send" may only send a new stream format that can not be 
received with old software.

--matt