I think I may have found a bug in dd or else something is wrong with amanda

Jim Dennis jimd at linuxcare.com
Tue Sep 12 18:26:30 PDT 2000


Apparently Christoph Scheeder <christoph.scheeder at scheeder.de>  wrote:

> Hi,
> not dd's fault. You are banging into the 2GB-Filesizelimit of linux.
> simple calculation: 65536 Blocks * 32k per block =2GB filesize.
> you'll never get the complete image back to the disk on the linux-box,
> as it is too large for the filesystem.
> you'll have to pipe the data directly into the restore-programm or
> to the remote-client.
> Christoph

  Note: you could dd the data (from the tape) to a raw partition
  on your Linux system (of=/dev/[hs]d[abcd...][12345...]).  That
  could act as a temporary storage area if you can't use a pipe
  for some reason.  I think Linux' 'restore' can use a raw device
  and I know GNU tar can do so.  

  (I've created 6Gb backup files on raw partitions -- and I've 
  tested that it will not over-write any other partitions on the
  same physical device, it will give an error if you try to write
  too much into the partition.  I've also use tar to extract from
  such raw disk partitions.  To do this just pick a partition and
  DON'T do a mkfs nor a 'mount' on it).
  
 
> Jeff Silverman schrieb:

>> Hi.  I think I have found a bug in dd, but before I go make a fool of
>> myself in front of FSF, I'd like to run it past you and see if you
>> agree.

>> I am trying to restore a file using amrestore and I am having mucho
>> trouble with the pipe breaking, so I decided to bypass amanda and do the
>> restoration by hand.

>> spinoza!root 528# dd if=/dev/nst0 bs=32k skip=1 of=dump_image_7
>> dd: dump_image_7: File too large
>> 65536+0 records in
>> 65535+0 records out
>> spinoza!root 529#   which dd
>> /share/bin/dd
>> spinoza!root 530# dd --version
>> dd (GNU fileutils) 4.0

>> I am not sure I believe this, but there is the distinct possibility that
>> there is a bug in dd, that it can't handle more than 64K records.  That
>> strains my credibility, surely I am doing something basic that's wrong.
>> This is gnu dd version 4 running on Linux 2.2.14-5 (Redhat 6.1).  The
>> machine being backed up is a PC running SunOS 5.6

>> I think the user's data is on the tape daily-008, file #9, but I just
>> can't get at it.  Any advice?

>> Jeff


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