Database dumps reflect a snapshot of a database at a given moment in time. The archive database that represents a database dump is read-only. No user transactions are allowed. Although the archive database is read-only, some modifications are allowed. For example:
You can run recovery to make the archive database consistent with the source database.
dbcc commands that perform fixes are allowed so that fixed versions of tables can be restored.
These modified and newly-allocated database pages cannot be stored within the database dump and its stripes, therefore an archive database requires some traditional database storage. This disk space is referred to as the modified pages section, and you can allocate it using the create archive database and alter database commands.
The modified pages section is divided into two segments:
The disposable changes segment stores any page that is modified or allocated by the recovery undo pass or any log page that is modified or allocated at any time. A page has only one entry in the disposable changes section.
The permanent changes segment stores any other page modification or allocation. A page has only one entry in the permanent changes section.
When you resize the modified pages section, sysusages rows are updated in the master database.
