Considerations for creating
ShadowImage pairs
Keep the following considerations in mind when creating SI pairs:
- The P-VOL and S-VOL must be the same size in blocks. If the capacity is displayed in GB or TB, a small difference between P-VOL and S-VOL capacity might not be displayed. To view the capacity in blocks, click in the Logical Devices window.
- If your storage system has encryption BEDs, you can copy an encrypted volume to an unencrypted volume. There is no guard logic to enforce copying encrypted P-VOLs to only encrypted S-VOLs. Unless there is a specific reason for the data to become unencrypted, make sure you maintain the encryption by using only encrypted S-VOLs.
- The larger the volume capacity, the longer the time from creation of a pair until it transitions to PAIR status. For virtual volumes, the more pages allocated to a virtual volume, the longer the time from pair creation to PAIR status. Even when no pages are allocated to a virtual volume, if the volume capacity is 60 TB, it takes at least 30 minutes until the status changes to PAIR after pair creation. If the volume capacity is 256 TB, it takes at least an hour.
- The value of the T10 PI attribute must be the same for the P-VOL and S-VOL.