Disk sanitization enables you to erase data from a disk or set of disks so that the data can never be recovered.
Before You Begin
Before you can use the disk sanitization feature, you must install the disk sanitization license.
Attention: Once installed on a storage system, the license for disk sanitization is permanent.
The disk sanitization license prohibits the following commands from being used on the storage system:
- dd (to copy blocks of data)
- dumpblock (to print dumps of disk blocks)
- setflag wafl_metadata_visible (to allow access to internal WAFL files)
For more information about licenses, see the System Administration Guide.
Considerations
You can sanitize any disk that has spare status.
If your storage system is using software-based disk ownership, you must ensure that the disks you want to sanitize have been assigned ownership. You cannot sanitize unowned disks.
Steps
- Verify that the disks that you want to sanitize do not belong to a RAID group in any existing aggregate by entering the following command: sysconfig -r
The disks that you want to sanitize should be listed with spare status.
Note: If the expected disks are not displayed, they have not been assigned ownership. You must assign ownership to a disk before you can sanitize it.
- Sanitize the specified disk or disks of all existing data by entering the following command:disk sanitize start [-p pattern1|-r [-p pattern2|-r
[-p pattern3|-r]]] [-c cycle_count] disk_list
Attention: Do not turn off the storage system, disrupt the storage connectivity, or remove target disks while sanitizing. If sanitizing is interrupted while target disks are being formatted, the disks must be reformatted before sanitizing can finish.
If you need to abort the sanitization process, you can do so by using the disk sanitize abort command. If the specified disks are undergoing the disk formatting phase of sanitization, the abort will not occur until the disk formatting is complete. Once the sanitizing is stopped, Data ONTAP displays a message informing you that sanitization was stopped.
-p pattern1 -p pattern2 -p pattern3 specifies a cycle of one to three user-defined hex byte overwrite patterns that can be applied in succession to the disks being sanitized. The default pattern is three passes, using 0x55 for the first pass, 0xaa for the second pass, and 0x3c for the third pass.
-r replaces a patterned overwrite with a random overwrite for any or all of the passes.
-c cycle_count specifies the number of times the specified overwrite patterns will be applied. The default value is one cycle. The maximum value is seven cycles.
disk_list specifies a space-separated list of the IDs of the spare disks to be sanitized.
- To check the status of the disk sanitization process, enter the following command:disk sanitize status [disk_list]
- To release sanitized disks from the pool of maintenance disks for reuse as spare disks, enter the following command:disk sanitize release disk_list
Data ONTAP moves the specified disks from the maintenance pool to the spare pool.
Note: Rebooting the storage system or removing and reinserting a disk that has been sanitized moves that disk from the maintenance pool to the broken pool.
The specified disks are sanitized, put into the maintenance pool, and displayed as sanitized. The serial numbers of the sanitized disks are written to /etc/sanitized_disks.
Examples
The following command applies the default three disk sanitization overwrite patterns for one cycle (for a total of 3 overwrites) to the specified disks, 8a.6, 8a.7, and 8a.8:
disk sanitize start 8a.6 8a.7 8a.8The following command would result in three disk sanitization overwrite patterns for six cycles (for a total of 18 overwrites) to the specified disks:
disk sanitize start -c 6 8a.6 8a.7 8a.8After You Finish
You can monitor the status of the sanitization process by using the /etc/sanitized_disks and /etc/sanitization.log files:
- Status for the sanitization process is written to the /etc/sanitization.log file every 15 minutes.
- The /etc/sanitized_disks file contains the serial numbers of all drives that have been successfully sanitized. For every invocation of the disk sanitize start command, the serial numbers of the newly sanitized disks are appended to the file.
You can verify that all of the disks were successfully sanitized by checking the /etc/sanitized_disks file.
