[OpenIndiana-discuss] latest snapshot deleted, breaking zfs send -i

[Martin Frost]

I do ZFS backups by creating daily snapshots and using zfs send & zfs
receive to copy each daily snapshot to a backup host, e.g.:

  zfs send -v -R -i foo at 2015.04.30 foo at 2015.05.01 | /usr/bin/ssh foo-n
fs-bak zfs receive -v -e backup

where 'foo' has a few subdatasets of the form foo/data/group/*.

Yesterday one of my colleages was freeing up some space by deleting
snapshots from one of the subdatasets on the source (not the backup
host).

Unfortunately, he deleted all of the snapshots for that subdataset,
including the very latest one.

That broke my backup scheme of sending incremental snapshots to the
backup host, since there is no longer a snapshot that exists on both.

Is there any way to recover from this and resume sending only
incremental snapshots to the same backup dataset?

It seems to me that the answer is no, that I now need to rename the
backup subdataset (to .old or something) and then do another 'initial'
send of a new snapshot that will transmit the entire source subdataset
(7 TB).  But I'd love to hear of some other way to resume sending
snapshots that doesn't require sending the full 7TB (which will also
use up extra space on the backup machine, duplicating much of the
existing subdataset there).

Thanks,
Martin