Am 26.05.22 um 04:10 schrieb Exuvo:
From my notes when i was doing recovery testing:
For some reason if i use encryption i get a single spurious error at
the end of amcheckdump or amrecover if you recover the last file written:
application stderr: /usr/bin/tar: Skipping to next header
application stderr: /usr/bin/tar: Exiting with failure status due to
previous errors
It still recovers as it should so nothing to worry about and manual
recovery from the same tape does not produce this warning but i have not
yet figured out why it happens.
I did do a complete 8TB restore when i first set up my archive backups,
which takes 7 tapes for me, changer worked, and that did give the above
warning at the end but all files matched the source when i checked.
I think i had "/bin/gzip: gzip: stdin: decompression OK, trailing
garbage ignored" before i used -q to zstd which suppresses warnings and
interactivity.
You could try a manual restore:
position at block 1 with mt fsb
mbuffer -i $TAPE -s 1024k -b 2048 -L | /etc/amanda/encrypt -d |
/etc/amanda/zstd-compression -d | tar -xf -
or mbuffer -i $TAPE -s 1024k -b 2048 -L | openssl enc -pbkdf2 -d
-aes-256-ctr -salt -pass fd:3 3< pwfile | zstd -dqcf | tar -xf -
That never gave the warnings as i get with amrecover but only feasible
for full restores.
You can try zstd -dfo /dev/null to see if zstd gives any warnings while
reading.
Thanks a lot for that detailed reply. Although in my case the
compression is with gzip, not with zstd. So I am unsure if your
suggestion applies.
A short search tells me that zstd is able to decompress gzip archives?
Nice, but the existing backups on tape tell amrecover to use "gzip -d"
or so, right?
I see people setting up a symlink .. hmm, wondering.
In my "define changer" section i have device-property "READ_BUFFER_SIZE"
"1024k", which i had to add to read older backups when i was testing
different block sizes.
That settings means it supports up to that blocksize for restores.
I don't have that setting yet.
Set it to 2048k now to match
blocksize 2 mbytes
readblocksize 2 mbytes
in the used tapetype (maybe all 3 settings could go into either the
tapetype OR the changer device-property lines).
