You will need to run a new FULL backup once the mode is changed back to FULL. Otherwise no tlog backups can be made.
The check for Full + tlog sequence is run by SQL Server, not LiteSpeed. LiteSpeed does the compression and encryption of the backups, but the basic part of the backup is all done by SQL Server. You could run this exact same test, getting the same results with the BACKUP DATABASE and BACKUP LOG commands.
See attached file for example.
Additional Information:
Run the following… (newcrash is my database..customer will edit as needed)
SELECT last_log_backup_lsn
FROM master.sys.database_recovery_status
WHERE database_id = db_id('newcrash')
When you switch from to simple recovery mode the results of this query will be “null” UNTIL you make full backup at which point there will be a LSN number returned by the query.
Taking a full backup when the database is in simple recovery mode does not update the below query results with an LSN number.
Only a full backup taken when the database has been set to the full recovery model will update the results with an LSN number.
This is called disabling " autotruncate mode" (IE: simple recovery).
To see what the recovery model is run the following( again "newcrash" is my database..edit as needed)
SELECT name, database_id, suser_sname(owner_sid) as owner ,
state_desc, recovery_model_desc
FROM sys.databases
WHERE name = 'newcrash'
Using both of these queries should tell you if a database is in full recovery AND that a new full backup has been taken thereby starting a new Tlog chain.
If the results are "null" for
SELECT last_log_backup_lsn
FROM master.sys.database_recovery_status
WHERE database_id = db_id('newcrash')
Then you will get one of two types of errors.
If in Simple mode:
"A transaction log cannot be taken in this mode" (or something close to this)
IF in full mode:
"no current full backup has been taken" (or something close to that).
