HP XP P9500 Storage - Manual (Page 38)

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If the P-VOL is already paired with other S-VOLs, before creating the new pair, check the
permitted status of existing S-VOLs. For more information, see
“Status of unaffected S-VOLs,
operations permitted ” (page 52) .
•
Because pair creation affects performance on the host, observe the following:
Create a pair when I/O load is light. ◦
◦ Limit the number of pairs that you create simultaneously.
•
When you create a pair, the S-VOL’s LDEV is allocated to the same processor blade to which
the P-VOL’s LDEV is allocated.
•
The paircreate operation overwrites all existing data on the S-VOL. The user is responsible for
backing up data on the S-VOLs before creating pairs.
•
If you use DKAs supporting encryption, you can create a BC Z pair by using an encrypted
volume and a non-encrypted volume. For example, you can create the pair specifying an
encrypted volume as the P-VOL and a non-encrypted volume as the S-VOL. In this case, data
in the encrypted P-VOL becomes non-encrypted data in the S-VOL.
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In the Create Pairs wizard, specify pair configuration settings that require additional
explanation.
For more information on setting up pair configurations, see “BC Z pair configuration in Create
Pairs wizard” (page 38) .
BC Z pair configuration in Create Pairs wizard
BC Z pair configuration uses the following process:
1. In the Create Pairs wizard, you will enter the number of S-VOLs that you want to pair. You
will set this number according to the pair with the highest number of S-VOLs.
2. If you are creating pairs with different numbers of S-VOLs, you will specify the highest number,
even when some pairs will not have that many S-VOLs.
3. You will remove volumes later in the Create Pairs wizard (see “Example 3” ).
Example 1
When you create a pair using one P-VOL and one S-VOL, the Number of Secondary Volumes is
set to 1.
When using one P-VOL and three S-VOLs (the maximum), the Number of Secondary Volumes is
set to 3.
Example 2
You may want to add a new S-VOL to an existing pair, as shown in the following figure. In this
case, the Number of Secondary Volumes is set to 2.
Example 3
If you wanted to create one pair with two S-VOLs, and another pair with one S-VOL at the same
time, set the Number of Secondary Volumes at 2. In this case, the system operates on the assumption
that you are creating two pairs, each having two S-VOLs.
38 Performing pair operations