HP XP P9500 Storage - Manual (Page 36)

Prerequisite information for creating pairs
•
Make sure that your volumes are set up for pairing. See “Planning pair volumes” (page 13)
for details.
•
Volumes should be in SMPL status. However, for L1 and L2 pairs, check “Status for L1, L2
pairs and operations permitted ” (page 51) for other permitted statuses.
•
When creating an L1 pair and an L2 pair at the same time, specify Non Split as the Split Type.
Doing this prevents failure, since using another split type can result in the split operation for
the L2 pair to begin before the pair is placed in PSUS status.
•
If the primary volume is already paired with other secondary volumes, before creating the
new pair, check the permitted status of existing S-VOLs in
“Status of unaffected S-VOLs,
operations permitted ” (page 53) .
•
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 a pair is created, the secondary volume’s LDEV is allocated to the same processor
blade that the primary volume’s LDEV is allocated to.
•
The paircreate operation overwrites all existing data on the secondary volume. The user is
responsible for backing up data on the secondary volumes before creating pairs.
•
If you use DKAs supporting encryption, you can create a Business Copy pair by using an
encrypted volume and a non-encrypted volume. For example, you can create the pair specifying
an encrypted volume as the primary volume and a non-encrypted volume as the secondary
volume. In this case, data in the encrypted primary volume will become non-encrypted data
in the secondary volume.
•
In the Create Pairs wizard, you will specify pair configuration settings that require additional
explanation. Please see
“BC pair configuration in Create Pair wizard” (page 36) for help in
setting up pair configurations.
BC pair configuration in Create Pair wizard
In the Create Pair wizard, you configure the pairs you are creating by a combination of setting
the number of secondary volumes you are pairing, and setting the pair topology, which is the ratio
of primary volumes to secondary volumes.
•
You set the number of secondary volumes according to the primary volume with the highest
number of secondary volumes.
•
You set the pair typology type according to the L1/L2 configuration with the highest number
of L2 volumes.
Pairs that have different topologies are configured initially with the same topology — though
you may not want them to have the same number of secondary volumes, nor the same L1/L2
configuration. In this case, you will specify the highest number of secondary volumes being
added to a primary volume, even when other pairs will not have that number; and you will
also set the topology according to this primary volume’s L1/L2 configuration. Later in the
wizard, you move volumes in other pairs to the correct configurations, or remove them to
achieve the correct configurations (see
Figure 11 (page 38) ).
Example 1
If you are creating an L1 pair with two secondary volumes, as shown below, the number of
secondary volumes is two and the pair topology is 1:2:-. This same pair configuration is also used
to add an additional secondary volume to an existing pair.
36 Performing pair operations