>>>The same way you'd write a tar archive to a tape that hasn't just been
>>>used for a ufsdump. As far as either program is concerned, a tape is
>>>a tape. Just make sure the tape really is wound to where you think it
>> OK, thanks.
>> So, how to *write* something to the tape?
>> cat foo.gz bar.gz bletch.txt > correctly-positioned-norewind-tape-drive-device ?
>Basically.. but.. :-)
>Unlike files, tapes tend to be "block-oriented". They don't properly
>handle requests for reads and writes less than the size of a block.
>Further, they tend to be much faster at larger sizes. So you probably
>want to "block" the file before writing. The 'cat' command will likely
>write in some block size, but you can't control it.
>Also, you can write multiple files to the tape, but how are you going to
>cat foo.gz bar.gz bletch.txt > /tmp/tempfile
>Now, how do you get the 3 files back? Generally, you don't. You'd use
>'tar' or 'zip' instead.
>Once you just have one file, you can use 'dd' to block it onto the tape,
>or if you're using tar, use it instead.
>dd if=/my/file of=/dev/rmt/0n bs=64k
>I pulled the 64k out of thin air. You'd want to use the same blocking
>figure both on input and output.
>read from tape:
>dd if=/dev/rmt/0n of=/tmp/tapefile bs=64k
>In general, though, you'd use tar.
>tar cbf 128 /dev/rmt/0n foo.gz bar.gz bletch.txt
>cd /tmp; tar xbf 128 /dev/rmt/0n
Thanks! Good explanations.
So, suppose I want to write a tar tape
to the tape (stuff *about* about a dump
I'm about to do), then I do a bunch of
ufsdumps, then append *another* tar tape
(full of stuff about the dump I actually
So, there's two ways "files" got written
to the tape: however the two tar-files
got written to the tape (via tar itself --
that'd be your advice, I guess), and
the 2nd method is via ufsdump.
So, to get the stuff *off* the tape, I'd
have to *invert* that process, by *remembering*
the order in which I did things to get that
stuff onto the tape, then doing the inverse
thing according to how a given "file" got
Without having those details written-down,
I guess you're lost, no?
Just asking hopefully-obvious questions to
make sure that I really do now understand it.