HI
i am using Sql server 200 . i am tryingto process the data cube in s analysis services but i am getting this error.
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The log file for database 'logfiles' is full. Back up the transaction log for the database to free up some log space.
Could not write a CHECKPOINT record in database ID 8 because the log is out of space.
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when i try to back up the transection log

i get error wrire on "dbname" failed status=112.See the SQL server error log for more details'

and in the log files it says

The backup data in 'logfiles backup' is incorrectly formatted. Backups cannot be appended, but existing backup sets may still be usable.

what should i do? i need to free the space in the log files so that i can perform more transections.
PLZ HELP