Fujitsu BS2OSD Manuale Utente
Page 20
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Limiting the I/O inclusion of single VM2000 guest systems (IOLVM)
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Less important guest systems that have intensive I/O activity,
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can severely impede other, much more important guest systems
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that use the same I/O resources.
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The IORM function can detect such conflict situations and
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intervene predictively. To do this, IORM continuously collects
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the utilization values for all known I/O devices, checks the
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settings for IOLVM and intervenes in the control if necessary.
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IOLVM only considers disk devices. As with the IOPT function,
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FDDRL, ARCHIVE, VOLIN and PAGING I/Os are not braked.
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Adapting the compression of LTO devices (TCOM)
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To ensure optimum data backup to LTO tapes, a minimum data rate
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must be maintained to keep the tapes continuously streaming.
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This minimum data rate is sometimes only achieved if the
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compression is disabled on the device. However, this reduces the
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tape capacity accordingly. By default, the compression is always
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enabled in BS2000/OSD-BC V6.0, even if IORM is not used.
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The compression can be fully disabled with the TCOM function.
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TCOM can also dynamically enable/disable the compression
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according to the data rate. The compression is disabled if the
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data rate is sufficient for tape streaming without compression
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but not with it.
2.16.2 Support for conversion from 7 bit to 8 bit character set
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By default, BS2000/OSD uses the 7 bit EBCDIC character set
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EDF03IRV with 95 printable characters and 65 control characters
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in the system. The designation 7 bit has established itself
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since the reproducible characters available correspond to the
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ASCII 7 bit character set although 8 bits are used for coding.
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Via the XHCS (Extended Host Code Support) subsystem, BS2000/OSD
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supports both the 7 bit and 8 bit character sets that encompass
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128 or 256 characters respectively.
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This allows BS2000/OSD to depict all languages that are defined
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in the international code tables as per ISO 8859. The concept of
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"coded character sets" (CCS) that defines the character coding
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in a file is used to depict the different character sets and
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codes. The programs get the information about the character sets
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from XHCS and do not have to store it themselves. Regardless of
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the input source, XHCS identifies the character sets via their
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character set names, the so-called CCS name, and makes them
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available in the form of tables.
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The class 2 option HOSTCODE=<CCS name> can be used to define a
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different, specific 8 bit EBCDI code instead of EDF03IRV for the
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complete BS2000/OSD system. Code definition via the CCS name is
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possible for separate IDs and pubsets.
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The default value for inputs on the terminal to TIAM, UTM and
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DCAM applications can be modified globally via the VTSU-B
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parameter file SYSPAR.VTSU-B.<vers>. Once the appropriate
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parameters are set, the character set of the home pubset for
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this ID apply. This is done for a single process with the command
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MODIFY-TERMINAL-OPTIONS CODED-CHARACTER-SET=*8BIT-DEFAULT.
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If data is converted from a 7 bit character set to an 8 bit one,
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the converted data must be distinguishable from the unconverted