6 Mar
2013
6 Mar
'13
12:31 p.m.
So what do you recommend instead of dd?
TCOPY has been mentioned. I usually suggest Eric Smith's tapeutils:
http://www.brouhaha.com/~eric/software/tapeutils/
which avoids needing two tape drives.
Also, this discussion hasn't yet specifically
stated, but I assume we're
talking about 9-track tapes here.
Many types support blockings other than a single fixed size: Exabyte
8mm, DLT and LTO, to pick a few common ones.
Do the same issues apply to QIC DC300 tapes? What
about DC100
(mini-QIC) tapes?
Maybe. Some implementations of QIC formats used a non-standard block
size, e.g. some of the Prime unix systems. As another odd case, the
Prime 50-series wrote the standard QIC fixed blocks, but the controller
managed variable sized blocks, writing a block length and flags into a
header in each tape block, then did reassembly on read.
I believe I've heard AS400 people kvetching about non-standard block
sizes on some tape format or another.
Short version, DO NOT USE dd TO IMAGE TAPES. Just don't. It's not hard
to use something that preserves the block structure, and then you don't
have to guess. Also, the archivists won't shoot you. :)
De