Thanks for the comments, all. I will do a few more dumps
to see what comes out, before committing to a split of
these DLEs.
some specific points:
<Gene Heskett>
| I might also add that 2.4.2 is very dusty these days, and it might
not
| hurt to bring it up to one of the 2.5.x versions. 2.4.2 has had
many
| years for bit rot to set in now, and it might be doing something a
wee
| bit differently than the current versions are.
Frankly, I'm afraid to do that. This is oldish hardware and OS, and
I'd rather not break things by trying to fix them. Or something.
(IRIX 6.5 on SGI Origin 200. Very easy on the eye.)
<Jon LaBadie>
| Guessing here. You are using DLT tape with a 35GB "native" capacity
| and believe the marketing hype that they are "70GB tapes".
|
| Further guessing. The previous amanda admin is using
| software compression
| (gzip) rather than letting the hardware compress things on
| the fly. This
| is very typical and normal. If so, amanda wants to know the native
| capacity of the tape and that is what is specified in the
"tapetype",
| setting. This is probably between 33&35GB, measured with the
| amtapetype
| program. If amanda has a history of these DLE it knows their
| compressibility.
| It may be more or less than the frequently claimed 50%.
|
| OTOH, if hardware compression is being used, most amanda admins find
| the 50% compression claim of the drive manufacturer to be
optimistic.
| Thue your admin may have listed the tapetype capacity of the drive
| as something lower than 70GB.
I'm entirely unaware of marketing hype. Or truth, for that matter.
This
is what I saw in amanda.conf:
tapetype DLT-7000
[snip]
# taken from http://www.cs.columbia.edu/~sdossick/amanda/
define tapetype DLT-7000 {
comment "DLT-IV op DLT-7000 drive"
length 33000 mbytes
filemark 8 kbytes
speed 5 mbytes
}
Aaaaand you're right. Dunno how I came up with that 70G figure.
Hrm. Combined with variable compression rates, that would account
for the [dump larger than tape, but cannot incremental dump
skip-incr disk] business.
Where would I look for hardware vs software compression?
--
Jurgen Pletinckx
AlgoNomics NV
|
