I noticed that the memory control panels limit of 8160 for a cache setting has been changed in OS 9.1

I have read threads on the cache setting limit before but no one has been able to describe definatively what it does or how it is used?
Is it similar to virtual memory?

Does anyone know the effects of raising this cache sky high?

I already have a gig of RAM in 450 DP, so i am wondering if it will hurt more than help if I raise it?

[Cipher13]

Put it to 16 megs.
The higher it is, the larger the disk cache which means certian recently accessed things will still be in RAM (processes), or whatever. Your free RAM will go down (with a gig that doesn't matter all that much ), and the higher it is, the longer it takes to find data in the cache. Setting it too high will result in slowdown. I have mine at 8 megs with 128 RAM/250 VM. No need for anymore. Try 16 see how it goes.
I don't really see much need for higher than 8160 though. It depends on what you do... what kinda stuff do you use it for?
PhotoShop for example would benefit from 16 megs over 8.

Cipher13

[elzinat]

From the Apple OS 9.1 Tech Note: http://developer.apple.com/technotes/tn/tn2010.html

The maximum disk cache size was increased to 32,736K (32M - 32K); the previous limit was 8160K (8M - 32K). This was done to help performance when allocating large files on large HFS Plus volumes (220GB and larger) initialized with the prior default allocation block size of 4KB.

For large volumes, the size of the volume's allocation bitmap can end up being bigger than the disk cache, causing the File Manager to do a huge amount of I/O when allocating space for a file. Setting the size of the disk cache to a value larger than the size of the bitmap allows the bitmap to remain in the cache, dramatically speeding up allocation requests.

When a volume uses 4KB allocation blocks (which was the default for large volumes initialized with Mac OS 9.0.4 or earlier), the allocation bitmap will be 32KB per GB of volume size. Volumes over 220GB initialized with Mac OS 9.1 default to an 8KB allocation block size, or 16KB of bitmap per GB of volume size. For example, when using a 200GB volume, the disk cache should be GREATER than 6400K; the next larger size is 6432K. When using a 400GB volume initialized with Mac OS 9.0, you should set the disk cache size to 12832K or larger for best performance.

Note that the default disk cache size is always less than 8MB (8192K), for maximum compatibility.

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be happy!
-mac freak