UNIX File-Descriptor Parameters

Some operating systems require you to specify a limit on the number of file descriptors that a process can have open at any one time. To specify this limit, use an operating-system configuration parameter, typically NOFILE, NOFILES, NFILE, or NFILES. The number of open file descriptors that each instance of the database server needs depends on the number of chunks in your database, the number of VPs that you run, and the number of network connections that your database server instance must support.

Use the following formula to calculate the number of file descriptors that your instance of the database server requires:

NFILES = (chunks * NUMAIOVPS) + NUMCPUVPS + net_connections 

chunks

is the number of chunks to be configured.

net_connections

is the number of network connections that you specify in either of the following places:

• sqlhosts file or registry
• NETTYPE configuration entries

Network connections include all but those specified as the ipcshm connection type.

Each open file descriptor is about the same length as an integer within the kernel. Allocating extra file descriptors is an inexpensive way to allow for growth in the number of chunks or connections on your system.