Re: [Bug-tar] Sparse file performance and suggestions

[Andreas Dilger]

On 2011-02-06, at 4:49, address@hidden wrote:
> Currently, tar seems to perform quite sub-optimally when archiving sparse
> files. I compared the performance of GNU tar and star when archiving a
> large (~2TB) sparse file. All but about 180MB of the file was holes.

There was a patch posted a while ago by Bernd Schubert to detect completely 
sparse files, bit I don't know if there was anything to automatically handle 
partially sparse files. 

> Sometimes it's possible to determine the exact hole layout in a file.
> Apparently that's quite easy in Solaris (SEEK_HOLE, SEEK_DATA) and
> Windows, less so in Linux (FIEMAP). 

A question to the tar maintainers - if someone were to write support for FIEMAP 
detecting holes on Linux would this be acceptable to include upstream?

Cheers, Andreas