SetCache is a little tool to set the read-ahead cache of a
Smart Filesystem drive.  This is not the same as the buffers
you can add using the AddBuffers command.

The read-ahead cache is used to prefetch information which
may be needed later on.  Because most harddisks don't suffer
a speed penalty when reading a bit more data this can
increase performance drastically.

It's command line syntax is:

 DEVICE/A,LINES/A/N,READAHEAD/A/N,NOCOPYBACK/S


DEVICE

The name of the device which you want to set the read-ahead
cache for.  Donot include a colon (":") after the device
name.  This only works for Smart Filesystem drives, and
won't do anything with the FastFilesystem.


LINES

Controls the number of read-ahead buffers.  Each buffer is a
specific bytes in size, which you can control using the
READAHEAD parameter.  It is a good idea to set this to
atleast 8 buffers or more.


READAHEAD

The number of bytes which the filesystem will read ahead.
This controls the size of the buffers you specified with the
LINES parameter.

The READAHEAD parameter will be rounded to a power of 2
automatically (for example, 5000 becomes 4096 (2^12)).


NOCOPYBACK

Turns off copyback mode.  There shouldn't be any reason why
you want to do this, short of testing purposes.  The
copyback mode is implemented in such a way that it can't
leave your disk in an incorrect state (just like the rest of
SFS).


If the SetCache command was succesful it will print the new
buffer size.  If it doesn't, then you either forget a
parameter (3 of them are required!) or you specified the
wrong drive name (donot include the colon ':'!)



Example
--------

SetCache SFS Lines=10 ReadAhead=8192

-> Set the read-ahead cache to 10 buffers of 8192 bytes each.