Fujitsu BS2OSD Manuale Utente

Page 20

Limiting the I/O inclusion of single VM2000 guest systems (IOLVM)

Less important guest systems that have intensive I/O activity,

can severely impede other, much more important guest systems

that use the same I/O resources.

The IORM function can detect such conflict situations and

intervene predictively. To do this, IORM continuously collects

the utilization values for all known I/O devices, checks the

settings for IOLVM and intervenes in the control if necessary.

IOLVM only considers disk devices. As with the IOPT function,

FDDRL, ARCHIVE, VOLIN and PAGING I/Os are not braked.

Adapting the compression of LTO devices (TCOM)

To ensure optimum data backup to LTO tapes, a minimum data rate

must be maintained to keep the tapes continuously streaming.

This minimum data rate is sometimes only achieved if the

compression is disabled on the device. However, this reduces the

tape capacity accordingly. By default, the compression is always

enabled in BS2000/OSD-BC V6.0, even if IORM is not used.

The compression can be fully disabled with the TCOM function.

TCOM can also dynamically enable/disable the compression

according to the data rate. The compression is disabled if the

data rate is sufficient for tape streaming without compression

but not with it.

2.16.2 Support for conversion from 7 bit to 8 bit character set

By default, BS2000/OSD uses the 7 bit EBCDIC character set

EDF03IRV with 95 printable characters and 65 control characters

in the system. The designation 7 bit has established itself

since the reproducible characters available correspond to the

ASCII 7 bit character set although 8 bits are used for coding.

Via the XHCS (Extended Host Code Support) subsystem, BS2000/OSD

supports both the 7 bit and 8 bit character sets that encompass

128 or 256 characters respectively.

This allows BS2000/OSD to depict all languages that are defined

in the international code tables as per ISO 8859. The concept of

"coded character sets" (CCS) that defines the character coding

in a file is used to depict the different character sets and

codes. The programs get the information about the character sets

from XHCS and do not have to store it themselves. Regardless of

the input source, XHCS identifies the character sets via their

character set names, the so-called CCS name, and makes them

available in the form of tables.

The class 2 option HOSTCODE=<CCS name> can be used to define a

different, specific 8 bit EBCDI code instead of EDF03IRV for the

complete BS2000/OSD system. Code definition via the CCS name is

possible for separate IDs and pubsets.

The default value for inputs on the terminal to TIAM, UTM and

DCAM applications can be modified globally via the VTSU-B

parameter file SYSPAR.VTSU-B.<vers>. Once the appropriate

parameters are set, the character set of the home pubset for

this ID apply. This is done for a single process with the command

MODIFY-TERMINAL-OPTIONS CODED-CHARACTER-SET=*8BIT-DEFAULT.

If data is converted from a 7 bit character set to an 8 bit one,

the converted data must be distinguishable from the unconverted