NonStop Server for Java 4.2 Programmer's Reference

NonStop system. For a processor on a NonStop system configured with 4 GB of physical memory, 512 MB are

used for the QIO segment. In addition, 512 MB of the user address space are reserved for the QIO segment, if the

process is also a QIO client.

To overcome the problem of losing address space to QIO, you can configure the QIO segment so that the segment

is moved to a special region of the privileged address space, called the KSEG2 region. Moving the QIO segment to

the KSEG2 region means that the maximum size of the QIO segment is restricted to 128 MB (instead of the default

512 MB). Before moving QIO to KSEG2, check that the current maximum QIO segment size in use is within the

128 MB limit (allowing for future requirements that may increase the QIO segment size). If the maximum QIO

segment size is within the limit, you can move QIO to KSEG2.

Example: Determining the QIO Segment Size in Use

To determine the QIO segment size in use, use the following SCF command from the TACL prompt:

TACL> scf

SCF - T9082G02 - (30APR03) (01APR03) - 03/19/2004 02:20:31 System \NAVAE1

(Invoking \NAVAE1.$DATA11.RAMR.SCFCSTM)

1-> status segment $ZM00, detail.

QIO Detailed Status SEGMENT \NAVAE1.$ZM00

State.................. DEFINED

Segment State.......... STARTED

Segment Type........... FLAT_UA

Segment Size........... 536870912

MDs in Use............. 1258

Max MDs Used........... 1589

Last Fail Size......... 0

Current Pool Size...... 16774788 Initial Pool Size...... 16776992

Max Pool Size.......... 16776992 Min Pool Size.......... 16776992

Current Pool Alloc..... 5039616 Max Pool Alloc......... 5128320

Current Pool Frags..... 12 Max Pool Frags......... 18

The maximum pool size used in this case is 16 MB, which is well below the 128 MB limit, so QIO can be moved

to KSEG2.

Example: QIO Segment Moved to KSEG2

The following SCF output shows the QIO segment as moved to KSEG2.

TACL> scf

SCF - T9082G02 - (30APR03) (01APR03) - 03/19/2004 02:20:00 System \GOBLIN

(Invoking \GOBLIN.$DATA11.RAMR.SCFCSTM)

1-> status segment $ZM00, detail

QIO Detailed Status SEGMENT \GOBLIN.$ZM00

State.................. DEFINED

Segment State.......... STARTED

Segment Type........... RESIDENT