Jobst Schmalenbach wrote:
When you want to extract tapes from a tape WITHOUT using amanda
how do you know which file a particular archive is located?
I print out a postscript label, generated by amreport, and store it
in the tapecasette. Some people use "amtoc" to generated a listing.
And there is the (slower) command "amrestore ConFig NoSuchHost",
or even a loop in shell using only dd and mt. Scanning the
headers does not take as long as reading the complete tape.
Wouldnt it be a good idea to have a "table of content" located
in the second BLOCk?
Some people (like Gene) write the necessary index and tools
as the last file on tape.
Amanda leaves the tape positioned at the end, just for just
purposes.
Ie: when amanda starts writing it writes a zero filled 32k
block to the second file and when its finshed doing all the
work put a file in there containing
archive_name1 directory1 FILEMARK1
archive_name2 directory2 FILEMARK2
archive_name3 directory3 FILEMARK3
This way you would only need to look up the block
and could blindly restore JUST by looking at the content
of the seocnd block.
Partitioning a tape is not done with standard commands.
Many tapedrives are not able to: if you write using the
standard open/write/close then everything after the last
close in the tape is gone, because the close also writes
an end of data mark.
Writing to a QIC-tape e.g. is done in a long serpentine,
where, when hitting the end of the tape the tape is reversed,
and the writing head is repositioned to write the data between
the tracks of the first pass, up to 4 or 8 passes hence and
forth over the tape. When writing the first pass, there is
an erase head that erases the complete width of the tape.
Maybe it is because I've seen too many bad things happen
with tapes and tapedrives, but I would not feel comfortable knowing
the tape is rewound and written to somewhere in the beginning,
and then hope the rest of the tape (with *ALL* the backups) are not
affected.
--
Paul Bijnens, Xplanation Tel +32 16 397.511
Technologielaan 21 bus 2, B-3001 Leuven, BELGIUM Fax +32 16 397.512
http://www.xplanation.com/ email: Paul.Bijnens AT xplanation DOT com
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