P9000 Volume Shredder for Open and Mainframe Systems User Guide (AV400-96405, October 2011)

2 Performing Volume Shredder operations
This module provides instructions for performing Volume Shredder operations.
Blocking volumes
The volume to be shredded must be blocked before the shredding operation. When the status of
a volume is blocked, I/O operations cannot be performed on the volume.
To block a volume:
1. Display the Remote Web Console main window.
2. Select Storage System in Explorer.
3. Select the resource under the Storage System folder.
Tabs are displayed:
• The LDEVs tab is displayed when a parity group in Parity Group is selected.
• The LDEVs tab is displayed when an LDEV in Logical Device is selected.
4. Find the volume to be blocked and check the status of the volume in the Status column.
• If Block is displayed, the volume is already blocked.
• If a status other than Block is displayed, the volume is not blocked. Continue to the next
step.
5. Select the volume and click Block LDEVs.
6. When the confirmation message is displayed, click Apply to block the selected volume.
Operation before shredding
Calculating the number of required shredding (for volumes using flash disk)
Before performing shredding operations, calculate the number of shredding operations that are
required in order to overwrite data in the target volume with dummy data. Because of the way
space is allocated in a flash disk, you must overwrite data with dummy data that exceeds the
capacity of the target volume.
Procedure 1 To calculate the number of required shredding operations:
1. Confirm that the capacity of the volume targeted for deletion and the number of data drive
making up the associated RAID configuration are displayed on the LDEVs tab when an LDEV
in Logical Device is selected.
Example: Confirmation of the number of data drives making up RAID configuration
n of RAID5(nxD + 1P)
n of RAID6(nxD + 2P)
2. Where the number of shredding operations necessary to overwrite data in the target volume
with dummy data is N, calculate using the following formula.
N (Rounding up after the decimal point) = (User-capacity-for-Data
*1
× 2) / Capacity-of-target-volume
*1: User capacity for data: Examples are shown as follows.
When the capacity of flash disk is 200 GB, 200 GB x n
When the capacity of flash disk is 400 GB, 400 GB x n
Example of calculating the number of required shredding operations:
Sample configuration: Flash disk is 200 GB, RAID configuration is 3D+1P, and LDEV is 220 GB
[(200 × 3) × 2] / 220 = 5.45
6 Performing Volume Shredder operations