Re: Interesting speed benchmarks

On Sat, 2007-Jan-27 11:54:37 -0500, Brian Reichert wrote:
On Sat, Jan 27, 2007 at 09:43:52AM +1100, Peter Jeremy wrote:
Note that dump/restore is the only tool that can correctly reproduce
sparse files. tar, cpio and pax also have filename and file size
restrictions. I don't think that cpio or pax support ACLs or file
flags.

I thought 'star' handled sparse files and all the extra magic? Not
that this is germaine to the topic at hand...

You can detect a sparse file by comparing the length of the file
with the number of allocated blocks. You can't determine whether a
specific block is all NULLs or not allocated without either bypassing
the filesystem (which dump does) or using a syscall to retrieve a
bitmap of allocated blocks (which FreeBSD doesn't have).

--
Peter Jeremy

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