From: | Neil Bothwick |
Date: | 28 May 2001 at 09:26:47 |
Subject: | Re: PFS3 |
Andrew Crowe said,
>> Used above settings successfully but am concerned about loss of
>> space. 500mb available on FFS reduced to around 472mb just through
>> using PFS3, seems ridiculous. That's around 6% unavailable.
> You're not really losing any space, you may actually me /gaining/
> space on the harddisk.
Correct.
> The reason for this size difference is that PFS allocates all the
> filespace for filenames/dir structures when you format it, while FFS
> saves it when writing files.
It also accounts for the massive speed increase when reading
directories. PFS has the directory table in one place, while FFS
scatters it all over the partition.
> IIRC PFS also uses less space for the file system structures, so if
> you tried to copy 500megs of FFS files over you'd probably be left
> with more free space at the end of it.
FFS uses a complete filesystem block for the headers and directory
information for each file. With a 1024K block size, a 1 byte file still
uses 2K of disk space. PFS keeps this data far more efficiently, so you
end up with more usable disk space.
Cheers
Neil
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