[Info-vax] Anyone interested in another public access system

[Bill Pechter]

In article <g22Fl.7857$U5.87390 at newsb.telia.net>,
Jan-Erik Söderholm  <jan-erik.soderholm at telia.com> wrote:
>Bill Gunshannon wrote:
>
>> 562 files, 2945723 used, 34908981 free (293 frags, 4363586 blocks,
>0.0% fragmentation)
>
>How is the %-frag calculated ?
>And is the data inside the () a specification of "free"
>or of both "free" and "used" ?
>
>It's a bit weird that 562 files with 293 frags = 0.0% fragmentation...
>
>Jan-Erik.

Fragments are less than the logical block size pieces of disk used by files
too small to fill the software disk block size. (Size depends on hw...)

http://en.wikipedia.org/wiki/Unix_File_System

"With larger block sizes, disks with many small files would waste a lot of space, so BSD added block level fragmentation (also called block suballocation, tail merging or tail packing), where the last partial block of data from several files may be stored in a single "fragment" block instead of multiple mostly empty blocks (Allen 2005)."


IIRC some BSD systems used 4k disk block sizes (multiples of the 512 byte
sector size).  The fragments were often 1k allocations out of one block
that would avoid wasting a ton of space.

IIRC, the 4k allocations were kind of like a cluster-size issue.  Gave the file
some breathing room before it needed further expansion.

Bill
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