When repairing or resetting with RECOVER, you can use foreign copies instead of the SESAM backup copies created using COPY. Foreign copies can be used to recover the following backup units:
individual user spaces
a space list
the catalog space
the entire database
A RECOVER on the basis of a foreign copy is generally performed in accordance with the same rules that apply to the same operation using SESAM backup copies (see section “Tasks associated with media recovery” and section “Recovering the database, catalog space and user spaces” ). Special characteristics of the use of foreign copies for a RECOVER operation are described below.
Special characteristics of the use of foreign copies for RECOVER operations
The user must copy the files for the foreign copy to the corresponding spaces. To do this, the spaces must be closed. In this case, SESAM/SQL simply updates the log files on the basis of the restart information present in the spaces. This does not affect SESAM backup copies.
RECOVER for user spaces with foreign copy
If you want to repair user spaces using a foreign copy then these spaces must have been logged at the time this foreign copy was created. The DA-LOG entry that is recorded as the restart point in the foreign copy must still be present in the metadata. Logging must not have been interrupted since the foreign copy was created. Any spaces that do not meet these conditions remain unchanged. Such spaces can only be subsequently accessed if they have not been modified since the time the foreign copy was created. If this is not the case, an error message informing you that the space is inconsistent is issued when you attempt to access such a space.
All the user spaces that are processed jointly (space list specification), must have the same time stamp ).
If a space was not logged at the time the foreign copy was created then it can only be reset to the status of the foreign copy.
RECOVER for a catalog space with foreign copy
If you want to repair a catalog space using a foreign copy then the restart point must still be present in the CAT-REC file. You can use any CAT-REC file state that was created during or after the generation of the foreign copy of the catalog space.
If the CAT-REC file is part of a foreign copy and is used for repair purposes then only a reset is possible to the status of this foreign copy. In this case, there are no further entries available to which the modifications could be applied.
RECOVER for a database with foreign copy
When the entire database is repaired, SESAM/SQL first repairs the database's catalog space followed by the user spaces.
If a database is repaired using a foreign copy in which the user spaces were backed up before the catalog space then any modifications will be applied to the spaces as required. If the user spaces were backed up later than the catalog space then the restart information is not present in the DA_LOGS table. A repair is not possible then.
If the whole database was not included in the logging upon creating the foreign copy, you can only reset to this state.
RECOVER for a database with foreign copy to a particular time
SESAM/SQL resets the entire catalog to the status at the specified time. When ANY is not specified, timestamp must identify the time of a SESAM backup copy of the catalog space. The SESAM backup copy must be entered in the CAT-REC file.
SESAM uses the foreign copy of the catalog space and applies the changes to the CAT-LOG files which were created subsequent to this SESAM backup copy up to the specified time. Subsequently the changes are applied to the DA-LOG files on the foreign copies in the user spaces up to the specified time.