>... I have noted that the amount of
>data backed up as reported by Amanda, though very close in size, is
>consistently a bit less than what 'du -sk' reports. This is a bit
>disturbing. One always wants to see the backup image, if not be exact,
>be at least a bit larger in size than the source image. Can anyone
>offer an explanation for this, ie. should I be concerned?
Three things come to mind. One is files with "holes", i.e. a file with
a size larger than what is physically allocated, such as the DBM files
for the E-mail aliases. The "du -sk" may or may not be taking those
into account.
It also may or may not take into account files with multiple links.
For instance, it may double count a file with two links that tar detects
and only backs up once.
The third (and probably best) possibility is that tar writes files in
units of 512 bytes. So if you have lots of short files (or lots that
fall in the lower half of 1 KByte boundaries), they will take less space
than rounding up all the sizes to KBytes.
>Paul Yeatman
John R. Jackson, Technical Software Specialist, [EMAIL PROTECTED]
