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Administrator's Reference

TAPEIOBUFS

Specifies how many tape I/O buffers the server can use to write to or read from tape media. The default is 1.

The server determines the value based on settings for the TXNBYTELIMIT client option and the MOVEBATCHSIZE, MOVESIZETHRESH, TXNGROUPMAX, and USELARGEBUFFERS server options. The server uses the maximum number of buffers it can fill before reaching the end of the data transfer buffer or the end of the transaction. A larger number of I/O buffers may increase I/O throughput but require more memory. The memory required is determined by the following formula:

number_of_buffers   x  32K  x  mount_limit
Note:
This option does not apply to device classes of the 3590 device type on servers running OS/390 Version 2 Release 10 or higher and on z/OS.

Syntax

>>-TAPEIOBUFS--number_of_buffers-------------------------------><
 
 

Parameters

number_of_buffers
Specifies the number of I/O buffers that the server can use to write to or read from a tape media. You can specify an integer from 1 to 9. A value of 1 means that no overlapped BSAM I/O is used. For a value greater than 1, the server can use up to that number of buffers to overlap the I/O with BSAM.

Examples

Specify that the server can use up to 9 buffers to overlap the I/O with BSAM:

tapeiobufs 9


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