number of devices

number of devices controls the number of database devices Adaptive Server can use. It does not include devices used for database or transaction log dumps.

When you execute disk init, you can also assign the virtual device number (the vdevno), although this value is optional. If you do not assign the vdevno, Adaptive Server assigns the next available virtual device number.

If you do assign the virtual device number, each device number must be unique among the device numbers used by Adaptive Server. The number 0 is reserved for the master device. You can enter any unused device number that falls in the valid range of values.

To determine which numbers are currently in use, enter:

select vdevno from master..sysdevices
   where status & 2 = 2

Here, “status 2” specifies physical disk.

If you are using a large number of devices on UNIX platforms, Sybase recommends that you set the appropriate number of devices and user connections in the configuration file. Attempting to configure a large number of devices dynamically using sp_configure may fail.

The number of network connections and number of devices configuration parameters use operating system file descriptors. You must increase the number of operating system file descriptors to use a large value for either configuration parameter.

What constitutes a large number of devices is platform-specific. These are the upper limits for the number of file descriptors for Adaptive Server:

• HPIA 64, HPPA 64, AIX 64, Windows – Set by Adaptive Server.

• IBM RISC 64-bit – 2000

• IBM PLinux – 2048

• AMD64 Linux – 10000

• IA32-bit Linux – 10000

• IA 64-bit Linux – 1024

If there are insufficient number of file descriptors, Adaptive Server issues an error message similar to:

Msg 5893, Level 16, State 1:Procedure 'sp_configure', Line 1234:
The sum, ( ((number of user connections) + (number of remote sites) + (max cisremote connections) + (number of java sockets)) / (max online engines)) + (number of devices ) + (max number network listeners), 
must be no greater than '958'.
Msg 5849, Level 16, State 1:Procedure 'sp_configure', Line 1234:
Verification failed for parameter 'number of devices'.
(return status = 1)

If you then set the number of file descriptors to 2048 with the command ulimit -n 2048 and restart the server, Adaptive Server reports this message in the error log when you increase the value for the number of devices:

kernel Using 2048 file descriptors.