For most users, a 1MB cache is sufficient. Devoting more memory to the cache offers diminishing returns, since the additional cache hits become fewer (and the extra memory could be better used to reduce swapping).
Typing SMARTDRV /S at a DOS prompt shows the cache size, a hit-and-miss report, and information about which drives are being cached. The hit-and-miss statistics are crucial for gauging the effectiveness of SmartDrive settings. A score in the high 80s shows that SmartDrive is well configured. Run SMARTDRV /S several times during a Windows session and note the-hit-and-miss figures each time. If your percentage usually falls below 80 percent, you should consider increasing the cache size. You can edit the SMARTDRV line in your AUTOEXEC.BAT file to increase both the InitCacheSize and the WinCacheSize parameters.