During the upgrade process, the log may get full due to the catalog changes that are made. If so, log in to the new server using isql, and issue:
isql> dump tran dbname with no_log
This frees the log space, and allow the upgrade process to continue.
In some cases, the pre-upgrade space estimations might be insufficient for the data copy phase of upgrade. In this case, you may get an error that there is insufficient space in the system segment for the upgrade. The upgrade process hangs, waiting for space to be provided. You can log in to the new server using isql, and use alter database to increase the size of the database.
isql> alter database dbname on device_name = "2m"
In 15.0 Adaptive Server, alter database allows you to specify the size to alter the database with the unit-specifier ‘m’, or ‘M’.