Sharing Thin Image volumes with ShadowImage

Thin Image User Guide
Version
9.8.6
Audience
anonymous
Part Number
MK-98RD9020-16

Available Thin Image tasks

You can share Thin Image (HTI) P-VOLs with ShadowImage (SI) P-VOL and S-VOLs.

The following table lists the Thin Image tasks you can perform when sharing a Thin Image P-VOL with a ShadowImage P-VOL.

HTI task

SI pair status

COPY(PD)/COPY

PAIR

COPY(SP)/COPY

PSUS(SP)/PSUS

PSUS

COPY(RS)/COPY

COPY(RS-R)/RCPY

PSUE

Create pair

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Store snapshot data

Yes

Yes

Yes

Yes

Yes

Yes

No

Yes

Restore pair

No

No

No

No

Yes

No

No

Yes

Delete snapshot data

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Release pair

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Legend:

  • Yes: You can perform the task.
  • No: You cannot perform the task (the command is rejected).

The following table lists the Thin Image tasks you can perform when sharing a Thin Image P-VOL with a ShadowImage S-VOL.

HTI task

SI pair status

COPY(PD)/COPY

PAIR

COPY(SP)/COPY

PSUS(SP)/PSUS

PSUS

COPY(RS)/COPY

COPY(RS-R)/RCPY

PSUE

Create pair

No

No

No

No

Yes

No

No

No

Store snapshot data

N/A

No

No

No

Yes

No

No

No

Store snapshot data for a consistency group

N/A

No

No

No

Yes*

No

No

No

Restore pair

N/A

No

No

No

Yes

No

No

No

Delete snapshot data

N/A

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Release pair

N/A

Yes

Yes

Yes

Yes

Yes

Yes

Yes

* The SI pair status must be "PSUS" during the period between when you create the HTI pair to store snapshot data and when HTI starts to store snapshot data for a consistency group, and when all of the pairs in the consistency group are split ("PSUS" status). If the SI pair status changes to a status other than "PSUS" while HTI is storing snapshot data for the consistency group, the snapshot data consistency cannot be guaranteed.

Available ShadowImage tasks

The following table lists the ShadowImage tasks you can perform when sharing a Thin Image P-VOL with a ShadowImage P-VOL.

SI task

HTI pair status

COPY

PAIR, PFUL

PSUS, PFUS

SMPL(PD)

RCPY

PSUE

Create pair

Yes

Yes

Yes

Yes

No

Yes

Create and split pair

Yes

Yes

Yes

Yes

No

Yes

Split pair

Yes

Yes

Yes

Yes

No

Yes

Normal Copy

Yes

Yes

Yes

Yes

No

Yes

Reverse Copy

Yes

Yes*

Yes

Yes

No

Yes

Quick Restore

No

No

No

No

No

No

Suspend replication

Yes

Yes

Yes

Yes

Yes

Yes

Delete pair

Yes

Yes

Yes

Yes

Yes

Yes

* After the pairsplit command is issued to the Thin Image pair for which a consistency group is specified, verify that all pairs in that consistency group become in "PSUS" status or single volumes, and then perform ShadowImage operations. If you perform ShadowImage operations without this verification, the consistency of Thin Image snapshot data with the P-VOL data at the point in time when the storage system accepted the pairsplit command cannot be guaranteed.

The following table lists the ShadowImage tasks you can perform when sharing a Thin Image P-VOL with a ShadowImage S-VOL.

SI task

HTI pair status

COPY

PAIR, PFUL

PSUS, PFUS

SMPL(PD)

RCPY

PSUE

Create pair

No

No

No

No

No

No

Create and split pair

No

No

No

No

No

No

Split pair

Yes

Yes1

Yes

Yes

No

Yes

Normal Copy

Yes

Yes1

Yes

Yes

No

Yes

Reverse Copy

Yes

Yes1

Yes

Yes

No

Yes

Quick Restore2

No

No

No

No

No

No

Suspend replication

Yes

Yes

Yes

Yes

No

Yes

Delete pair

Yes

Yes

Yes

Yes

Yes

Yes

  1. After the pairsplit command is issued to the Thin Image pair for which a consistency group is specified, verify that all pairs in that consistency group become in "PSUS" status or single volumes, and then perform ShadowImage operations. If you perform ShadowImage operations without this verification, the consistency of Thin Image snapshot data with the P-VOL data at the point in time when the storage system accepted the pairsplit command cannot be guaranteed.
  2. When a host accesses a Thin Image S-VOL, the storage system needs to return data in theThin Image P-VOL. Therefore, the Quick Restore operation (which switches the ShadowImage P-VOL and S-VOL (which is the Thin Image P-VOL)) cannot be performed.

You can perform ShadowImage pair tasks after you store snapshot data, but the consistency of the stored snapshot data is not guaranteed.

Thin Image S-VOLs use the data in the P-VOL. You cannot Quick Restore in ShadowImage.

For more information about ShadowImage tasks and pair statuses, see the Hitachi ShadowImage® User Guide.

CAUTION:
Thin Image uses MU numbers 0 to 1,023, and they are assigned in the order of 3 to 1,023, followed by 0 to 2. ShadowImage uses MU numbers 0 to 2. Thin Image cannot use the MU numbers 0 to 2 if you want to share Thin Image volumes with ShadowImage.

To share Thin Image volumes with ShadowImage if Thin Image is using the MU numbers 0 to 2:

  1. Delete the Thin Image pair of the MU number 0 to 2.
  2. Create the ShadowImage pairs and Thin Image pairs.