7.7.6.2 DROP CELL

Purpose

The DROP CELL command resets a cell to its original state.

Syntax

DROP CELL [ERASE = value] [FORCE] 

Usage Notes

• This command is run from within the cell.

• All cell disks, grid disks, and thresholds are dropped. The interdatabase plan is reset to its default state. All cell attributes are set to default values.

• The FORCE option is required if the grid disks are configured on any cell disks when DROP CELL is issued. Otherwise, an error is reported.

• Flash cache compression must be disabled before securely erasing a drive.

• The ERASE option erases the content on the disk by overwriting the content. The values are as follows:

  • 1pass: One pass, and the content is overwritten with zeros. This value is not available for flash drives.

  • 3pass: Three passes, and the content is overwritten with set data patterns. This option follows the recommendations of NNSA. This value is not available for flash drives.

  • 7pass: Seven passes, and the disk is overwritten with set data patterns. This option follows the recommendations from DOD.

• When dropping all cells using the 1pass or 3pass option, it necessary to drop the flash disks first using the 7pass option, and then drop the cells. The following is an example of the commands:

  CellCLI> DROP CELLDISK ALL FLASHDISK ERASE=7pass 
  CellCLI> DROP CELL ERASE=1pass 
  

• Starting with Oracle Exadata System Software release 19.1.0, if you specify to erase hard disks or flash disks using 1pass, 3pass, or 7pass method on Oracle Exadata Database Machine X5 or later, Oracle Exadata System Software automatically invokes Secure Eraser to erase the disks. Secure Eraser determines whether or not the disks can be erased using the better and faster cryptographic erasure method. If some of the disks are eligible, then the cryptographic erasure method is used to erase those disks, and the originally requested method (1/3/7 pass) is used on the other disks. This feature is not used on system disks.

  See Table 7-3 for a list of the erasure methods available for each type of device.

The following table shows approximate time needed to securely erase a drive using the supported algorithms. When multiple grid disks or cell disks are dropped with the ERASE option, the command runs in parallel on all disks and flash drives. However, the recommended method of erasing data from a cell is to use Secure Erase. See Securely Erasing Database Servers and Storage Servers in Oracle Exadata Database Machine Security Guide.

Table 7-2 Estimated Erasure Times for Devices by Erasure Method

Type of Device	1pass	3pass	7pass	Cryptographic
600 GB hard drive	1 hour	3 hours	7 hours	not available
1.2 TB hard drive	1.67 hours	5 hours	11.67 hours	not available
2 TB hard drive	5 hours	15 hours	35 hours	not available
3 TB hard drive	7 hours	21 hours	49 hours	not available
4 TB hard drive	8 hours	24 hours	56 hours	not available
8 TB hard drive	13.17 hours	39.5 hours	92.17 hours	1 min
10 TB hard drive	14 hours	42 hours	98 hours	1 min
14 TB hard drive	18 hours	54 hours	126 hours	1 min
22.875 GB flash drive	not available	not available	21 minutes	not available
93 GB flash drive	not available	not available	32 minutes	not available
186 GB flash drive	not available	not available	36 minutes	not available
1.6 TB flash drive	not available	not available	5.5 hours	1 min
3.2 TB flash drive	not available	not available	8 hours	1 min
Persistent Memory (PMEM) device	not available	not available	not available	1 min
4 GB Internal USB	not available	30 minutes	not available	not available
8 GB Internal USB	not available	1 hour	not available	not available
150 GB M.2 device	not available	not available	not available	1 minute
ILOM	not available	not available	not available	1 minute

Example 7-126 Dropping a Cell

CellCLI> DROP CELL FORCE