Editing NetWare (section)

=== Aggressive caching ===
From the start, the NetWare design focused on servers with copious amounts of RAM. The entire file allocation table (FAT) was read into RAM when a volume was mounted, thereby requiring a minimum amount of RAM proportional to online disk space; adding a disk to a server would often require a RAM upgrade as well. Unlike most competing [[network operating system]]s prior to Windows NT, NetWare automatically used all otherwise unused RAM for caching active files, employing delayed write-backs to facilitate re-ordering of disk requests ([[Elevator algorithm|elevator seeks]]). An unexpected shutdown could therefore corrupt data, making an [[uninterruptible power supply]] practically a mandatory part of a server installation.

The default dirty cache delay time was fixed at 2.2 seconds in NetWare&nbsp;286 versions 2.''x''. Starting with NetWare&nbsp;386&nbsp;3.''x'', the dirty disk cache delay time and dirty directory cache delay time settings controlled the amount of time the server would cache changed ("dirty") data before saving (flushing) the data to a hard drive. The default setting of 3.3&nbsp;seconds could be decreased to 0.5&nbsp;seconds but not reduced to zero, while the maximum delay was 10&nbsp;seconds. The option to increase the cache delay to 10&nbsp;seconds provided a significant performance boost. Windows&nbsp;2000 and 2003 server do not allow adjustment to the cache delay time. Instead, they use an algorithm that adjusts cache delay.