DISKCACHE

Note: This entry was written pertaining to LAN Server 2.0, not 3.0. Still, the DISKCACHE information is interesting.

With Entry Server 2.0 there is a cache feature that will allow you to allocate extra memory to caching. This is the DISKCACHE parameter and it will allow you to set the size of this cache to a maximum of 14.4MB. The way DISKCACHE works is as follows:

All read requests to an HPFS drive, greater than 2KB and less than or equal to the DISKCACHE threshold value, are placed in DISKCACHE. So, DISKCACHE works in conjunction with HPFS cache accepting data reads greater than 2KB which is the largest size HPFS cache can accept. DISKCACHE has two parameters. The threshold value and the total memory to set aside for DISKCACHE. So the command DISKCACHE=2048, 128 would set the DISKCACHE to 2 Meg and the maximum size, in sectors, of a read request to 128, which is the threshold. So, in short, the LAN Server Entry package does provide additional caching functionality.

However, even though the Entry package provides this functionality, the Advanced Package running on OS/2 1.3 will provide better performance.

One of the main performance improvements is in the 386 HPFS cache. The 386 HPFS cache has a more intelligent caching algorithm in addition to the following features:

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Performance is enhanced by the use of Busmaster disk and network device drivers that increase overlap of network and disk activity. This function is called scatter/gather and allows devices to transfer data to and from cache independently of the CPU, hereby increasing disk and CPU overlap.

The directory information is also cached.

DISKCACHE operates with FAT and HPFS when running Entry Server and operates with only FAT when running the Advanced Server. DISKCACHE operates with FAT only with the 1.3 server code.

CACHE is for HPFS, but will work in conjunction with DISKCACHE on normal HPFS systems.