AT&T MERLIN LEGEND Release 3.1, System Programming Manual

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Using SPM
2–22
Programming with SPM
Determining the Release Number
of a Backup File
If you have a backup diskette but do not know its release number, you may be
able to find this information in the backup header. Beginning with later versions
of Release 1.1, the backup file contains a backup header 128 bytes long.
Approximately 59 of these bytes are currently used. Bytes 55 through 59 of the
header contain the MERLIN Legend Communication System Release number, as
shown in Table 2–4. (Release 1.0 and early versions of Release 1.1 do not
contain this information in readable form.)
Table 2–4. Backup Header: Release Number
Release No. Build No. System Size Mode
Size 2 bytes 12 bytes 1 byte 1 byte
Examples
03 00 32 01 01 - Key
02 01 02 - Behind Switch
03 - Hybrid/PBX
The release number is found in the first two bytes (four characters) of the
identification number. For example, 0300 = 3.0, 0201 = 2.1.
If the backup file is compressed, you can read the header but you cannot read
the data area following the header. Use
type
[ backup filename ] to read the
header on a DOS system or
cat
[ backup filename ] to read the header on a UNIX
System.
Note that the communication system release number, not the version number of
SPM, reflects whether the backup file is compressed or uncompressed. Release
1.0 backups are uncompressed and Release 1.1 and later backups are
compressed. Uncompressed files take longer to restore.
Considerations
Review the following items before you begin the backup procedure:
■ The communications system does not have to be idle during backup;
however, extension programming is blocked.
■ Any objects that are in a maintenance-busy state are stored in that state.
When you restore system programming, these objects are busied out,
even if they have since been released from the maintenance-busy state.
■ If you plan to store your backup file on a diskette, format a DOS diskette.
(DOS formatting can be done on a UNIX System PC or a DOS PC).
■ Uncompressed backup files are 100,000 to 210,000 bytes in size;
compressed files are about 70,000 to 85,000 bytes.