QMS 2060 Reference page 140

The amount of memory needed for the disk cache client is dependent
on the size of the disk, the number of disks, the number of subdirecto-
ries on each disk, and the amount of memory dedicated to caching.
As long as the disk cache is enabled and there is enough memory in
the disk cache, all disks are accessible. If insufficient memory is allo-
cated to the disk cache, some disks may be seen while others are
not.
The recommended amount of memory for the disk cache client is
128 KB minimum plus 0.5 KB per MB of disk storage total for all
disks
For example, the recommended amount of memory for the disk cache
for a single 1200 MB hard disk is 728 KB, and for two 1200 MB hard
disks it is 1456 KB. These are recommended values. The printer will
still operate with a smaller cache, but decreased performance may
result.
This field on the status page shows the size of the physical RAM
installed in the printer. If a hard disk is installed and disk swapping is
enabled (Administration/Memory/Enable Disk Swap), this field also
gives the size of available virtual memory.
Also known as System Use, this non-configurable client is the amount
of RAM used to run the printer's operating system. It's never
increased or decreased. The system memory subtracted from the
total amount of RAM identifies the amount of RAM available for all the
other memory clients.