When running with large data sets, one should configure the Virtuoso process to use between 2/3 to 3/5 of system RAM and to stripe storage on all available disks. See NumberOfBuffers , MaxDirtyBuffers , and Striping INI file parameters.

; default installation
NumberOfBuffers          = 2000
MaxDirtyBuffers          = 1200

Typical sizes for the NumberOfBuffers and MaxDirtyBuffers (3/4 of NumberOfBuffers) parameters in the Virtuoso configuration file (virtuoso.ini) for various memory sizes are as follows, with each buffer consisting of 8K bytes:

Table 16.19. recommended NumberOfBUffers and MaxDirtyBuffers

System RAM NumberOfBuffers MaxDirtyBuffers
2 GB 170000 130000
4 GB 340000 250000
8 GB 680000 500000
16 GB 1360000 1000000
32 GB 2720000 2000000
48 GB 4000000 3000000
64 GB 5450000 4000000

Also, if running with a large database, setting MaxCheckpointRemap to 1/4th of the database size is recommended. This is in pages, 8K per page.