UPDATE SAVE PROCEDURES

The Ultimate system provides several ways of performing a file save on only the disk data base files that have been changed or updated since the last file save. You may select an update save option from the SYSPROG Main Menu, or use the system commands ALL-UPDATE-SAVE or PART-UPDATE-SAVE.

Remember that an update save tape contains only files that have been flagged as "updated" since the last file save.

The update save feature is designed to provide a fast,

efficient way of protecting the disk data base and minimizing data loss in case of a power failure or system hardware or software problems. Instead of saving the complete data base with every file save (as described in section 3.3), with update save you can shortcut the backup procedure and save only the files that have changed since the last full file save.

There are two main features in the update save concept:

1. Making an "incremental" file-save. with this facility, only those file groups that have been changed since the last file save are saved. The Incremental File-save is also called the "Update Save".

2. Logging all transactions (i.e., all updates to all files) to a secondary medium, magnetic tape.

Transaction logging is explained in section 3.5, TRANSACTION LOGGING PROCEDURES.

Two system commands perform procedures associated with update saving: ALL-UPDATE-SAVE, and PART-UPDATE-SAVE. These

commands are procs that execute specific forms of the SAVE command. Two options, U and R, are added to the SAVE verb.

The U option specifies that the SAVE command will save only data that has been changed since the last save. This is done at the group level of all files in the system.

Associated with each group of each disk file is a flag indicating whether any item in the group has been updated.

with the U option specified, the SAVE command inspects these flags, and saves those groups that have the flags set. The R option is used to reset those flags after the groups are saved on tape.

The save tape obtained with the U option is called an update save tape. To restore the system, the latest "full" file-save tape is first restored, and then the update save tapes are loaded to update the files.

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The update save feature and transaction logging can be used together to provide the greatest possible security for a data base. See Section "USING UPDATE SAVE AND TRANSACTION LOGGING TOGETHER" •

NOTE: If the system is not already running on Rev121A or later, i t must be upgraded before the update save commands can be used.

Follow the appropriate procedure in the UPGRADE PROCEDURE document to upgrade your system. The update save commands will not work unless the--appropriate upgrade procedure is followed.

If the system is not upgraded properly, an attempt to use update save commands will cause the system to display an error message:

Configuration error; F-restore required While the update save and transaction logging procedures provide system flexibility, users are cautioned to carefully read the sections pertaining to these features before using them. Failure to follow the appropriate procedures may result in losing all updates that have occurred since the last file save.

The Update Save Options Available with the SAVE Command Two options, U and R, are used with the SAVE command to

specify update save operations. with the U option specified, the SAVE command inspects the "group-updated" flags, and

saves those groups that have the flags set.

The R option is used to reset each "group-updated" flag after the associated group is saved on tape. The R option can be used either with or without the U option to reset the

group-updated flags.

The U and R options must be used in conjunction with other existing options to do the saves. For example, to do a full file-save and to reset the "group-updated" bits, the command

"SAVE (D,F,G,R,S,T)" must be used.

In order to minimize operator errors, several forms of the SAVE command have been stored as procs so that different

"save" operations can be easily requested. These "file save"

procs must be executed from the SYSPROG account; they are:

FILE-SAVE (full file save)

SAVE command format: SAVE (D,F,G,R,S,T) ALL-UPDATE-SAVE (complete update save)

SAVE command format: SAVE (D,F,G,T,U)

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PART-UPDATE-SAVE (partial update save)

SAVE command format: SAVE (D,F,G,R,T,U) SYS-GEN (complete SYS-GEN tape)

SAVE command format: SAVE (D,F,G,S,T,Z)

These procs provide two methods of using update saves. The main difference between the two methods is that the PART-UPDATE-SAVE resets the "group-updated" flags, while ALL-UPDATE-SAVE does not. This means that a "partial" update the data base:--The disadvantage is that each ALL-UPDATE-SAVE procedure could require more time and tape since i t saves (or tape on each PART-UPDATE-SAVE procedure. The disadvantage is that the full file save tape and all subsequent

Partial update save (via ALL-UPDATE-SAVE) daily.

Restore data base, as needed, with most recent File prematurely with the following warning message:

[994] Full file save required

Because the last PART-UPDATE-SAVE was aborted, the update save tape is incomplete and is otherwise useless. Yet some (but not all) of the

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"group-updated" flags are already reset by the R PART-UPDATE-SAVE together (e.g., do an ALL-UPDATE-SAVE on Monday and a PART-UPDATE-SAVE on Tuesday), i t makes the restore procedure undesirably confusing and complex.

Ultimate recommends that the user choose a system back-up procedure, either the ALL-UPDATE-SAVE or the PART-UPDATE-SAVE proc, depending on the size, applications and other

requirements of the system, and consistently use only that one procedure.

Update Save with Re-allocation Parameters

If there is a re-allocation parameter in the definition item (attribute 13 of the D pointer item) of a file, and if the re-allocation parameter has different values of modulo and/or separation from those of the file, the entire file is saved

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PROBLEM: CHANGING REALLOCATION PARAMETERS items were re-hashed and reallocated into the appropriate groups. However, when loading the PART-UPDATE-SAVE tape, only the updated groups are present. The items in these

sequencing information segment. The Z option indicates that this file save is not in the usual sequence of file saves for

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