tar 从磁带 恢复数据

gm3000

小弟想从磁带中恢复以前的备份数据，使用 tar -xvf /dev/rmt/2m 但是报了一条 directory checksum error，换了好几个磁带都是这样，不知道怎么回事，哪位大哥能不能给个提示？

rainer_man

Tar reads the stored checksum from the tape and also uses other fields
read from the tape to compute a checksum.  When these checksums do not
match, errors will display of this nature.  The errors typically happen
from backup media because the media somehow has been damaged or
de-magnetized but other possibilities are listed below :

   1. The tar tape might not be a tar tape at all and could be a cpio,
      fbackup, or some other backup utility tape.

   2. The tar could have been written using the "O" option which is the
      pre-POSIX format and not the normal default of "N" which is the
      POSIX format.

   3. The block factor was not the default and specified with the "b"
      option.

   4. Verify what options were used to create the tar archive.

   5. Check to make sure that tar is the current patched version for
      the operating system and also any kernel drivers that have been
      patched.

   6. Do not rule out hardware.  Attempt to archive off some files to
      a scratch tape and restore them.  Make sure that the drive is
      performing as it normally should.