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Not a silly thing, but dangerous.
Authored by: Scott Byer on Apr 12, '02 04:06:00PM

Head movement time on disk drives is still significant, as is dealing with fragmentation. HFS+ still fragments reasonably quickly, so a dynamically grown swapfile can still suffer performance issues related to that.

The best thing to have is a small, fast drive dedicated to swapping. Second best is a dedicated partition, but thrashing of the disk head can negate those gains if the physical disk that partition is on is not partitioned "wisely".

Swap files are accessed frequently, and often in very small chunks (system VM page size), and if the system isn't and can't coalesce the I/Os from the swap file, other heavy activity on the same physical disk can significantly impact performance.

!!!BUT!!! This is a dangerous area if you're not familiar with start-up init states, especially related to mounting volumes.

There is a GUI program I saw somewhere (swapcop?) which definitely does some incorrect things when moving the swap, which can really mess up a system.



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