HP StorageWorks XP Remote Web Console Software - Manual (Page 64)

Cache and Nonvolatile Storage (NVS)
Cache and nonvolatile storage (NVS) must be operable for both the primary storage system and
secondary storage system of a URz data volume pair. If not, the URz add pair operation will fail. The
remote storage system cache should be configured to adequately support not only the local workloads
but also the URz remote copy workloads.
Duplicate Volumes
Since the contents of the primary data volume and secondary data volume of a URz pair are identical,
the secondary data volume can be considered a duplicate of the primary data volume. Since the host
operating system does not allow duplicate volumes, the host system administrator must take precautions
to prevent system problems related to duplicate volumes. You must define the URz secondary data
volume so they do not auto-mount or come online to the same host at the same time as the primary
data volume (see WARNING below).
URz does not allow the secondary data volume to be online (except while the pair is split). If the
secondary data volume is online, the URz add pair operation will fail.
WARNING: If the URz secondary data volumes are physically attached to the same host server(s) as
the URz primary data volumes, the following problem can occur:
When a URz pair is released, the old secondary data volume is usually offline. If the host is then
restarted, the system administrator may be offered both volumes and asked which volume should be left
offline. This can be confusing and is prone to error.
If the URz secondary data volumes and primary data volumes are connected to the same host(s), HP
strongly recommends that the secondary data volumes are defined to remain offline to avoid this problem.
Installing the Hardware
Initial installation of the URz hardware is performed by the user and the HP representative. To install the
hardware required for URz operations:
1. User: Identify the locations of the URz primary and secondary data volumes (primary data
volumes and secondary data volumes), so that the URz hardware can be installed and
configured properly.
2. User and HP Representative: Make sure that the primary storage system(s) and secondary
storage system(s) are configured for XP Remote Web Console operations (e.g., SVP connected
to LAN). Refer to the XP Remote Web Console user’s guide for information and instructions on
setting up XP Remote Web Console operations.
3. HP Representative: Make sure that the primary storage systems and secondary
storage systems are properly configured for URz operations (e.g., cache, NVS) (see
“ Cache and Nonvolatile Storage (NVS) ” on page 64. Make sure that the desired system option
modes are enabled (see Table 3 on page 37). Make sure that adequate cache is installed and
available for URz operations. You must also consider the amount of Cache Residency Manager
data to be stored in cache when determining the required amount of cache.
4. HP Representative: Make sure the primary storage systems are configured to report sense
information to the host(s). The secondary storage systems should also be attached to a host
server to enable reporting of sense information in case of a problem with an secondary data
volume or secondary storage system. If the remote site is unattended, the secondary storage
systems should be attached to a host server at the primary site, so that the system administrator
can monitor the operational condition of the secondary storage systems.
5. HP Representative: If power sequence control cables are used, set the power select switch for the
cluster to LOCAL to prevent the primary storage system from being powered off by the host. Also
make sure the secondary storage system will not be powered off during URz operations. See
“ Setting up Remote Copy Connections ” on page 65 for further information on powering off/on
the primary storage systems and secondary storage systems.
64 Preparing for Universal Replicator z/OS Operations