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Thread: "WARNING: got more data then expected" when trying "create_compressed_fs"

  1. #1
    Junior Member
    Join Date
    Apr 2011

    "WARNING: got more data then expected" when trying "create_compressed_fs"

    Hello, I have not been able to find information about a 'create compressed fs' warning and was hoping someone may point me in the right direction.

    My remastering attempts are generating a warning about an incomplete image when I try 'create_compress_fs'. Can this warning be ignored, or does it indicate problem with my remastering approach?

    Here is how I am generating the ISO:

    mkisofs -o /home/INNER.remastered.iso  \
                           -hide-rr-moved -cache-inodes 
                           -pad -R -U -V Boot_Disk 
                           -v -allow-multidot 
    The mkisofs is run on a Debian machine. In a successful remastering, I get the following block sizes:

    Done with: The File(s)                             Block(s)    70087
    Writing:   Ending Padblock                         Start Block 71979
    Sometime (and I can't figure out why), I get different block sizes when trying to remaster the same files. I get the following block sizes when 'create_compressed_fs' exists with the above warning:

    Done with: The File(s)                             Block(s)    70086
    Writing:   Ending Padblock                         Start Block 71978
    There is a difference of 1 in the above block sizes.

    I compress the inner filesystem with the following command:

    create_compressed_fs -v -m -B 65536 \
                                     /home/INNER.remastered.iso \
    The command exits with 1 and produces the following warning:

    [ 9] Blk#  2249, [ratio/avg.   6%/ 37%], avg.speed: 3205565 b/s, ETA: 0s
    [ 9] Blk#  2250, [ratio/avg.   0%/ 37%], avg.speed: 3206989 b/s, ETA: 0s
    WARNING: got more data then expected. Trailing data is ignored, your image may be incomplete.[ 9] Blk#  2251, [ratio/avg.   0%/ 37%], avg.speed: 3208414 b/s, ETA: 0s
    [ 9] Blk#  2252, [ratio/avg.   0%/ 37%], avg.speed: 3209839 b/s, ETA: 0s
    [ 9] Blk#  2253, [ratio/avg.   0%/ 37%], avg.speed: 3211264 b/s, ETA: 0s
    gzip(0):     0 (    0%)
    gzip(1):     0 (    0%)
    gzip(2):     0 (    0%)
    gzip(3):     0 (    0%)
    gzip(4):     0 (    0%)
    gzip(5):     0 (    0%)
    gzip(6):     0 (    0%)
    gzip(7):     0 (    0%)
    gzip(8):     0 (    0%)
    gzip(9):  2254 (1e+02%)
    7zip:     0 (    0%)
    Writing index for 2254 block(s)...
    Writing compressed data..
    Does anyone else see this warning message?

    Any suggestions on how to debug or fix this intermittent warning?

    Thank you,

  2. #2
    Senior Member
    Join Date
    Jan 2011
    Hi Jon Jaroker and welcome to the Knoppix forums.

    No reply probably means no one has seen this warming or they just don't take any notice. After a couple of days your post has dropped down the list and it unlikely to get a reply.

    Yes, it would be really nice is someone knew that mkisofs has simply got its block count wrong and the warning from create_compressed_fs was just noting thismk.

    I can't see anything wrong with your methodology except possibly character sets.

    Googling does not help much: compressed_fs is not widely used outside of Knoppix and mkiosfs isn't: it's geniosimage. It's a 'dead fork' created around 2007 as a result of a difference of interpretation of 'free' that failed to be reconciled in the usual amicable fashion that the Open Software movement is so famous for. Wikipedia mentions character sets as a possible root cause.

    It means if you Google for mkisofs you don't know which hits refer the version you are using and which refer to the real thing. The syslinux site's isolinux page (Knoppix LiveCD uses isolinux as a boot loader) recommends 1.1.13 but Knoppix has the 'dead fork' version 1.1.11 (which claims to be equivalent to 2.01 of the original). Meanwhile the original mkisofs has moved on to version 3.

    You may be able to check the integrity of the output of genisoimage using the tools described by:

    man isoinfo
    I think genisoimage should give you an md5sum. Run this for yourself to check. See

    man md5sum
    To check the integrity of your compressed image you would need to associate it with a spare cloop device:

    losetup /dev/cloop1 /home/remaster/master/KNOPPIX/KNOPPIX
    It should then be possible to run md5sum and isoinfo et al on /dev/cloop1.

    There is other stuff you could so but you are not going to get the bug (if there is one) fixed. If I were worried by the warning I would not trust the output. I would regenerate the iso until I got compression with no warning.

    I don't see why genisoimage should have any hardish memory or processor requirement but to be on the safe side, I'd run these commands while my machine was otherwise idle and all big applications closed. That is while I'm asleep, out to work or just watching a real television.

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