Data-reduced volumes* can be used as SIz P-VOLs or S-VOLs.
* On VSP One B85, a data-reduced volume is a DRS-VOL. On VSP One B20 series, a data-reduced volume is a V-VOL with capacity saving enabled.
If you are using DP volumes as SIz P-VOLs or S-VOLs, the capacity of the DP pool allocated to the volume is added to the SIz licensed capacity.
Restrictions
- Because the S-VOL uses the same pool capacity as the P-VOL, best practice is to avoid the following volume combinations:
- Using only the S-VOL as a DP-VOL.
- Using a P-VOL that is a DP-VOL with the Data Direct Mapping attribute with an S-VOL that is a normal DP-VOL.
- (VSP One Block 20 series) You cannot perform a Quick Restore if capacity saving is enabled for the P-VOL or S-VOL.
- (VSP One Block 85) You cannot perform a Quick Restore in any of the following conditions:
- Only the P-VOL is a DP-VOL.
- Only the S-VOL is a DP-VOL.
- A DRS-VOL is used for either of the P-VOL or the S-VOL.
- If an ESE-VOL is used as a P-VOL or S-VOL, you can perform Quick Restore only when both of the following conditions are satisfied:
- Both the P-VOL and S-VOL are ESE-VOLs.
- If SOM 1256 is disabled, the CU numbers for the P-VOL and S-VOL and the IDs of the pools that the P-VOL and S-VOL belong to are all even numbers or all odd numbers.
- You cannot perform ShadowImage for Mainframe pair operations while the DP-VOL is being expanded.
- When you create a ShadowImage for Mainframe pair using a DP-VOL that is larger than 262,668 cylinders, the differential data is managed by control cylinder information written in pages that are assigned in the SIz pair volume. In this case, the required pool capacity for managing the differential data is one page for every 4,096 cylinders. When pages are not assigned to the SIz pair volume, pages for recording control cylinder information might be created during the creation of SIz pairs. However, if pages have been assigned for all of the area in the volume, it is not required to add the pool capacity for managing differential data since the page format for control cylinder information and for user data is same. The control cylinder information for ShadowImage for Mainframe, TrueCopy for Mainframe, and Compatible FlashCopy® is recorded in the same pages.
- If the copy origination page of an SI pair is not allocated, but the copy destination page is already allocated, zero data is copied to the copy destination. In this case, zero data pages are not reclaimed. If you want to reclaim zero data pages, split the SI pair to change its status to PSUS, and then reclaim zero data pages of the applicable volume.
- When the ShadowImage for Mainframe pair status is PSUP/SUSPVS or COPY/TRANS, the DFSMSdss SPACEREL or ICKDSF INIT command for releasing the pages in the DP pool is accepted, but the pages are not released. Wait until the pair status changes to PSUS (or SSUS)/SUSPOP, and then execute the command.