DP-VOL protection function

The DP-VOL protection function enables you to protect the DP-VOLs in a pool from read and write requests when problems occur in the pool or pool volumes. For example, in a pool consisting of pool volumes assigned to parity groups with accelerated compression enabled, the access attribute of the DP-VOLs changes to Protect when the capacity reserved for writing is depleted.

You can use the Create Pools window or the Edit Pools window to set the following DP-VOL protection options:

• Protect V-VOLs when I/O fails to Full Pool Enable this option to protect the DP-VOLs using the pool from read and write requests when the pool usage reaches the full size.
• Protect V-VOLs when I/O fails to Blocked Pool VOL Enable this option to protect the DP-VOLs using the pool from read and write requests when the pool-VOL is blocked.

The requirements for using the DP-VOL protection function are:

• Data Retention Utility (DRU) must be installed.
• The pool type must be Dynamic Provisioning or Dynamic Tiering. The DP-VOL protection function cannot be set for Thin Image pools.

The behavior of the DP-VOL protection function depends on the settings of system option modes (SOMs) 729 and 803, as specified in the following tables.

SOM 729	Protect V-VOLs when I/O fails to Full Pool	Behavior
OFF	Disabled	DRU Protect attribute is not set
OFF	Enabled	DRU Protect attribute is set
ON	Disabled	DRU Protect attribute is not set
ON	Enabled	DRU Protect attribute is set

SOM 803	Protect V-VOLs when I/O fails to Blocked Pool VOL	Behavior
OFF	Disabled	DRU Protect attribute is not set
OFF	Enabled	DRU Protect attribute is set
ON	Disabled	DRU Protect attribute is not set
ON	Enabled	DRU Protect attribute is set

When the access attribute of a V-VOL was changed to Protect, if you change the access attribute to other than Protect, use the Data Retention window. The setting by the DP-VOL protection function has no connection to the access attribute status of DP-VOL. For example, even if you disabled the DP-VOL protection function to the pool while the Protect attribute was being enabled on the DP-VOL, the Protect attribute would still be enabled on the DP-VOL.

If you remove the Data Retention Utility feature, the V-VOL protection function settings remain set in the pool but are no longer active. In this case, if you reinstall Data Retention Utility, the protection function settings made before Data Retention Utility was removed are reactivated in the pool.