TC can share an SI P-VOL in three configurations:
- In the following figure, the TC P-VOL also functions as an
SI P-VOL. This
configuration allows you to use SI for on-site data
backup in case of TC failure.
Or, the TC S-VOL can
be used to provide remote backup of the SI P-VOL in case of an
SI failure. Figure. Shared TC P-VOL with SI P-VOL
In this configuration, you can only delete TC pairs when the SI P-VOL status is COPY(RS-R)/RCPY. The following table shows possibilities of TC pair operations according to the SI P-VOL status.
TC pair operations SI P-VOL status COPY(PD)/COPY
COPY(SP)/COPY
COPY(RS)/COPY
PAIR
PSUS(SP)/PSUS
PSUE
PSUS
COPY(RS-R)/RCPY
Create Yes Yes Yes Yes No Split P-VOL specified Yes Yes Yes Yes No Split S-VOL specified Yes Yes Yes Yes No Resync P-VOL specified Yes Yes Yes Yes No Resync S-VOL specified Yes Yes Yes No No Delete Yes Yes Yes Yes Yes Switch operations between the primary and secondary sites (horctakeover) Yes Yes Yes No No - In the following figure, the TC S-VOL also functions as an
SI P-VOL. In this
configuration, SI provides another (or
several more) backup copies of a TC P-VOL.
When an SI P-VOL is shared with the TC S-VOL, the write operation to the TC P-VOL takes a longer time than normal. This is especially true when the SI pair is in the PSUS(SP)/PSUS status and is caused by the SI copying process. The processing time is increased by the processing time for SI added to the normal TC unit copy processing. The processing time might be increased by dozens of milliseconds with the addition of SI.
Figure. Shared TC S-VOL with SI P-VOL
In this configuration, you can only delete TC pairs when the SI P-VOL status is COPY(RS-R)/RCPY. The following table shows possibilities of TC pair operations according to the SI P-VOL status.
SI P-VOL status
TC pair operations
Create
Split
Resync
Delete
Switch operations between the primary and secondary sites (horctakeover)
P-VOL specified
S-VOL specified
P-VOL specified
S-VOL specified
COPY(PD)/COPY
COPY(SP)/COPY
COPY(RS)/COPY
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
PAIR
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
PSUS(SP)/PSUS
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
PSUS
PSUE
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
COPY(RS-R)/RCPY
No
No
No
No
No
Yes
No
* When the P-VOL and the S-VOL of a TrueCopy pair are used as the DP-VOL of Dynamic Provisioning, if you share the P-VOL of a ShadowImage pair with the S-VOL of the TrueCopy pair, you must delete the ShadowImage pair before creating the TrueCopy pair. For details, see Dynamic Provisioning. - In the following figure, the
configurations shown in the previous two figures are combined. Both the TC P-VOL and S-VOL function as SI P-VOLs, providing
multiple copies at the primary and secondary sites. Figure. Shared TC P-VOL, S-VOL with multiple SI P-VOLs
In this configuration, you can only delete TC pairs when the SI P-VOL status is COPY(RS-R)/RCPY. The following table shows possibilities of TC pair operations according to the SI P-VOL status.
SI P-VOL status
TC pair operations
Create
Split
Resync
Delete
Switch operations between the primary and secondary sites (horctakeover)
P-VOL specified
S-VOL specified
P-VOL specified
S-VOL specified
COPY(PD)/COPY
COPY(SP)/COPY
COPY(RS)/COPY
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
PAIR
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
PSUS(SP)/PSUS
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
PSUS
PSUE
Yes*
Yes
Yes
Yes
Yes
Yes
Yes
COPY(RS-R)/RCPY
No
No
No
No
No
Yes
No
*(VSP E series) If the TC P-VOL and TC S-VOL are DP-VOLs, the TC S-VOL cannot be used as the SI P-VOL.