10.6.2 Exadata Secure Erase

Oracle Exadata System Software includes a method to securely erase and clean physical disks before redeployment. The ERASE option overwrites the existing content on the disks with one pass, three passes or seven passes. The one pass option overwrites content with zeros. The three pass option follows recommendations from NNSA and the seven pass option follows recommendations from DOD.

The following table shows the approximate times needed to securely erase a drive using the supported algorithms.

Type of Drive	One Pass	Three Pass	Seven Pass
600 GB drive	1 hour	3 hours	7 hours
2 TB drive	5 hours	15 hours	35 hours
3 TB drive	7 hours	21 hours	49 hours
22.875 GB flash drive	NA	NA	21 minutes
93 GB flash drive	NA	NA	32 minutes

Note:

• Oracle Exadata System Software secure data erase uses multiple over-writes of all accessible data. The over-writes use variations of data characters. This method of data erase is based on commonly known algorithms. Under rare conditions even a 7-pass erase may not remove all traces of data. For example, if a disk has internally remapped sectors, then some data may remain physically on the disk. This data will not be accessible using normal I/O interfaces.

• Using tablespace encryption is another way to secure data.