The following table lists the requirements for Thin Image Advanced P-VOLs and S-VOLs. If you create pairs without specifying S-VOLs, S-VOLs are not required.
Item |
Requirements |
---|---|
Volume type |
Data reduction shared volume |
Emulation type |
OPEN-V |
Path definitions |
LU path definitions are not required. |
Maximum capacity |
256 TB |
Maximum number of snapshot datasets | A maximum of 1,024 S-VOLs can be used in a snapshot tree. A maximum of 64 layers (L64) can be created in a cascade configuration. |
Information about DRS-VOL usage
When you use data reduction shared volumes for Thin Image Advanced pairs, note the following:
- Data reduction shared volumes can be used for quick copy because Thin Image Advanced pairs logically copy compressed and deduplicated data.
- When data reduction shared volumes are used with ShadowImage pairs, host I/O performance might be degraded because compressed and deduplicated data is once expanded and then compressed and deduplicated again.
- When data reduction shared volumes are used with TrueCopy, Universal Replicator, or global-active device pairs, host I/O performance might be degraded because compressed and deduplicated data is expanded and then sent.
- Data reduction shared volumes consume a pool for the user data and the management information.
- Data reduction shared volumes for which accelerated compression is enabled cannot be used for creating pairs.
- A data reduction shared volume can be used up to the maximum size for a Thin Image Advanced P-VOL or S-VOL.
- When a host issues the WriteSame/Unmap command to a Thin Image Advanced P-VOL or S-VOL, zero pages are not reclaimed by the WriteSame/Unmap command. Also, zero pages are not reclaimed by HDvM - SN or CCI.
- Thin Image Advanced pair creation might be rejected if the Unmap command operation is in progress with system option mode 905 ON. Wait a while and then retry the operation. If the operation still fails, set system option mode 905 to OFF and try again.