@Vulture
Too late to use LZX now, it's still archiving 12 hours later and I don't want to stop it :-)
@Keropi
I would try that, but the HDD is SCSI and I don't have access to a PC (let alone one with SCSI support).
This is a one-off, so leaving it archiving across the network is acceptable just this once even if it takes 24 hours.
--
moto