Connect to database fails with ORA-09817, ORA-01075

Normal user could not connect to your database and whenever you try to connect to your database with user having SYSDBA privilege it returns error ORA-09817, ORA-01075.
-bash-3.00$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Mon Jul 28 04:14:44 2008

Copyright (c) 1982, 2005, Oracle. All rights reserved.

ERROR:
ORA-09817: Write to audit file failed.
Solaris-AMD64 Error: 28: No space left on device
ORA-01075: you are currently logged on

Cause of the Error: Database could not write to audit file because of Solaris-AMD64 Error: 28.No space left on device. In the partition where audit file resides has no free space.

Solution of The Problem:
The only solution is make more free space in the partition where audit file resides. You can see the audit file destination in the pfile parameter audit_file_dest. By default the location is
$ORACLE_HOME/admin/$ORACLE_SID/adump.
First you can check the available space in your partition by,
-bash-3.00$ df -h
/dev/dsk/c1d0s3 24G 24G 0K 100% /oracle

Now delete the unnecessary files in the partition.
Like rm -r /oracle/test