Supported pair statuses for consistency group pair-split

ShadowImage User Guide

Version
9.8.7
Audience
anonymous
Part Number
MK-98RD9021-17

The pair status for all of the SI pairs in the CTG determines if you can perform a consistency group (CTG) pair-split. If all of the SI pairs in the CTG are paired (PAIR status), you can perform a CTG pair-split.

The following table describes when you can perform a CTG pair-split, based on the SI pairs in the CTG that are not paired (a status other than PAIR), and the resulting pair status after you perform the pair-split.

The status of the pairs in the CTG that have a status other than PAIR

Can you perform

a CTG pair-split?

Status after you perform a CTG pair-split

COPY(PD)/COPY

YES

PSUS

COPY(SP)/COPY

YES2

PSUS

PSUS(SP)/PSUS

YES2

PSUS

PSUS

YES2

PSUS

COPY(RS)/COPY

NO

The command ends abnormally and shows the following information:

[EX_CMDRJE] An order to the control/command device was rejected1

The pair statuses remain the same.

COPY(RS-R)/RCPY

NO

The command ends abnormally and shows the following information:

[EX_CMDRJE] An order to the control/command device was rejected1

The pair statuses remain the same.

PSUE

NO

The command ends abnormally and shows the following information:

[EX_CMDRJE] An order to the control/command device was rejected

The pair statuses remain the same.

Notes:

  1. If you share a UR S-VOL and an SI P-VOL, the command might end normally after you perform a CTG pair-split. Ensure the status of the pairs within the CTG have changed to PSUS (use the pairdisplay command).
  2. Consistency is guaranteed only for SI pairs in PAIR or COPY(PD)/COPY status.

The following are examples of when you can perform a CTG pair-split based on status of the SI pairs in the CTG:

  • Example 1

    The are six SI pairs in a CTG. Two of the pairs are paired (PAIR status), two are in COPY(PD)/COPY status, and two are in PSUS status. In this case, you can perform a CTG pair-split, and doing so changes the status of all of the pairs in the CTG to PSUS. However, the S-VOLs that were in PSUS might not be consistent with the other volumes in the CTG.

  • Example 2

    There are two SI pairs in a CTG and one is paired (PAIR status) and the other is in the process of being resynchronized (COPY(RS)/COPY status). In this case, you cannot perform a CTG pair-split.

  • Example 3

    The are six SI pairs in a CTG. Two of the pairs are paired (PAIR status), two are in the process of Quick Split (PSUS(SP)/PSUS status), and two are in PSUE status. In this case, the CTG pair-split ends abnormally and the status of all of the pairs in the CTG remains the same.