buffers

[buffers]
buffers=16384

The number of kilobytes of memory to allocate for caching files. This value can also be specified with the −buffers command tail on the database manager. There is no need for this to be an exact power of 2, but usually only quite large changes in the value will make a significant difference to performance.

The best value to use in any particular in any installation is difficult to predict, and can only be found by experiment. The following advice should be treated with caution.

• Unless you use the 4.622 bypass_cache=2 setting, the default number of buffers will usually work well, and even lower values, such as 8192 will usually work well. If you do use the bypass_cache=2 setting, you should not use a lower value, as it will probably degrade performance, and higher values are more likely, but by no means certain, to be beneficial.
• You should probably never specify a value greater than 50% of the available memory. Unless you are sure it is beneficial, it is suggested that you should allocate no more than 65536 buffers on machines with IDE hard drives, and 32768 buffers on machines with SCSI or hardware RAID hard drives. Allocating extra buffers is more likely to be beneficial on IDE hard drives than SCSI drives.
• You should probably never specify a value that exceeds twice the size of all the databases that will be open at the same time.
• If you choose to specify a large value, such as buffers=65536 and you are using 4.620 or 4.621, then make sure you set lazy_writes=0. These two releases of DP4 have a performance bug, which becomes severe when very many buffers are used.