On Fri, 21 Apr 2017 23:46:27 +0100, The Natural Philosopher
 wrote:

>On 21/04/17 23:39, Sidney_Kotic wrote:
>> Lots of stuff in another thread about file systems.
>>
>> I mentioned defragmentation.  There seems to be a lack of understanding
>> about what it is.  Has zilch to do with the TOC.
>>
>> ----
>> In the maintenance of file systems, defragmentation is a process that
>> reduces the amount of fragmentation. It does this by physically
>> organizing the contents of the mass storage device used to store files
>> into the smallest number of contiguous regions (fragments). It also
>> attempts to create larger regions of free space using compaction to
>> impede the return of fragmentation. Some defragmentation utilities try
>> to keep smaller files within a single directory together, as they are
>> often accessed in sequence.
>>
>> Defragmentation is advantageous and relevant to file systems on
>> electromechanical disk drives. The movement of the hard drive's
>> read/write heads over different areas of the disk when accessing
>> fragmented files is slower, compared to accessing the entire contents of
>> a non-fragmented file sequentially without moving the read/write heads
>> to seek other fragments.
>> ----
>> https://en.wikipedia.org/wiki/Defragmentation
>>
>> Way back in the stone-age things like this were important when you were
>> concerned about seek time and how it impacted performance.
>
>And is one of the reasons that Linux uses by and large file systems
>designed with all this in mind that don't actually fragment files. And
>massive file caching too, so that memory that isn't needed for anything
>else is acting as a fast random access copy of bits of the disk that you
>have used recently.
>
>
>Of course these days with SSDS who gives a ****. The relationship
>between a requested track/sector isn't anything like constant as wear
>levelling algorithms rearrange the SSD on a routine basis anyway.
>
>And there is no seek time.

I love the "blah blah blah" in reference #4 in the Wiki cited. Very
academic.
--

Graham.
%Profound_observation%

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