defrag

[Ivan Voras]

Bill Moran wrote:
> In response to Ivan Voras <ivoras at fer.hr>:

>> I believe that a "fragmented file" in common usage refers to a file
>> which is not stored continuously on the drive - i.e. it occupies more
>> than one continuous region. How is UFS fragmentation different than
>> fragmentation on other kinds of file systems?
> 
> That common usage refers to Windows filesystems.
> 
> In unix filesystems, fragmentation refers to the number of blocks that have
> been broken down in to fragments to either hold files smaller than a block,
> or (as you mentioned) use the space at the end of a file that doesn't fit
> exactly in a block.

Ok, so the difference is in the name, not in the semantics :)
Unfortunately, all the world is Windows now and that's why I try to use
"block fragments" instead of just "fragments" to try avoid confusion.

> But this also makes it _easy_ for the filesystem to avoid causing the type
> of fragmentation that _does_ degrade performance.  For example, when the
> first block is on track 10, then the next block is on track 20, then we're
> back to track 10 again, then over to track 35 ... etc, etc
> 
> Keep in mind, that in the previous 3 paragraphs, I was using the "Windows"
> definition of "fragmentation."

Agreed.

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