Yeah, the 'normal' slow speed I can live with - but it was the fact the hang was occurring when it
wasn't doing the transfer is what got me.
I've put in a WD Caviar Black 2TB in its place, gone through the same setup procedure (enabling softupdates, noatime), and tried the same folder. This time the transfer speed was a normal-looking 4.5MB/s - not spectacular, but certainly fast enough in comparison to ~380K.
I'm starting the full backup again from scratch now, and all appears to be running normally:
Code:
# zpool iostat share 2
capacity operations bandwidth
pool alloc free read write read write
---------- ----- ----- ----- ----- ----- -----
share 2.61T 8.27T 122 8 10.0M 28.0K
share 2.61T 8.27T 358 0 44.5M 0
share 2.61T 8.27T 200 0 24.9M 0
share 2.61T 8.27T 432 0 53.7M 0
share 2.61T 8.27T 352 0 43.7M 0
share 2.61T 8.27T 311 0 38.7M 0
I think I'll give the green drive another go in a linux or windows box, and see if it has any similar issues - it hasn't before now, so I'm curious to see the result. I'll update if it's interesting.
Thanks for the help, consider this solved!