Subject: Re: hexdumping large sparce files
To: None <firstname.lastname@example.org>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
Date: 01/24/2003 18:33:01
> Is there anything in the kernel that could be used to speed up the
> dumping of very large, very sparce files?
> For instance I would like to be able to verify the non-zero parts of
> the following file:
> $ ls -ls z
> 192 -rwxr-xr-x 1 dsl wheel 14797279232 Jan 24 22:31 z
> without actually transferring 14Gb of data from kernel to user.
> (and maybe without filling all of physical memory with 0 bytes).
Well, it's only a little like what I assume you're looking for, but if
the file is on an FFS filesystem, I have code that knows how to read
the disk directly and detect holes in the file that way.
Drop me a line if you're interested in discussing it further.
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