BAR_XFER_BUFSIZE (XPS)

onconfig.std value

8 pages

if value not present

32,768 / pagesize for platform

units

PAGESIZE which can be 2, 4, or 8 kilobytes

range of values

1 to 15 pages

takes effect

When the onbar_w utility starts

The BAR_XFER_BUFSIZE configuration parameter specifies the size of each transfer buffer. The actual size of a transfer buffer is BAR_XFER_BUFSIZE * PAGESIZE + 500. The extra 500 is for overhead. For example, if BAR_XFER_BUFSIZE is 15 and the page size is 4 kilobytes, the transfer buffer should be 61,440 bytes.

For generally good performance, set to 8, although different storage managers might suggest other values. The maximum value that XBSA allows is 64 kilobytes.

If you set BAR_XFER_BUFSIZE to 8 when the page size is 8 kilobytes, the database server decrements the transfer buffer size to 7 pages so that the maximum value would be under 64 kilobytes (7 * 8 = 56). ON–Bar displays a warning message if the transfer buffer size is decremented.

To calculate how much memory the database server needs, use the following formula:

kilobytes = BAR_WORKER_MAX * BAR_XFER_BUFSIZE * 
            BAR_XPORT_COUNT * PAGESIZE

For example, you would need at least 1600 kilobytes of memory for the transfer buffers for five onbar-worker processes if the page size is 4 kilobytes.

1600 kilobytes = 5 workers * 8 pages* 10 buffers * 4 kilobytes