HP StorageWorks XP Remote Web Console Software - Manual (Page 34)

XP Continuous Access does not allow the S-VOL to be online (except when the pair is split). If the
S-VOL is online, the XP Continuous Access paircreate operation fails.
CAUTION: If XP Continuous Access S-VOLs are physically attached to the same host servers as
XP Continuous Access P-VOLs, a problem might occur. When an XP Continuous Access pair is
deleted, the old S-VOL 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 XP Continuous Access S-VOLs and P-VOLs are connected to the same hosts, HP strongly
recommends that you define S-VOLs to remain offline (or create them with the RAID Manager no
read option) to avoid this problem.
Host system crash
Contents of the P-VOL and S-VOL of an XP Continuous Access pair may become inconsistent if the
host system hangs (crashes) while a write operation is being performed on the XP Continuous
Access P-VOL, and the write operation cannot be retried because of the following reasons:
•
A check condition is reported to the host due to a failure in the disk array when the write
command for the XP Continuous Access pair is issued.
•
A reset command is issued from the host, and the write operation is stopped (write operation
is incomplete).
If these conditions occur, retry the job to complete the write operation.
Installing hardware
Initial installation of the XP Continuous Access hardware is performed by the user and the HP
representative. Hardware configurations for XP Continuous Access Synchronous and XP Continuous
Access Asynchronous are the same.
1. User: Identify locations of XP Continuous Access primary and secondary volumes (P-VOLs and
S-VOLs) so that the necessary storage system and connecting hardware can be installed and
configured properly.
2. HP representative: Make sure that the MCUs and RCUs are configured for storage system
operations (for example, that the SVP is connect to a LAN. See the HP StorageWorks XP
Remote Web Console user guide: HP XP12000 Disk Array, HP XP10000 Disk Array, HP 200
Storage Virtualization System for information and instructions on setting up Remote Web
Console operations.
3. HP representative: Ensure that MCUs and RCUs are properly configured for XP Continuous
Access operations (for example, cache and NVS) (see
“Cache and nonvolatile storage (NVS)”
(page 33) ). Ensure that adequate cache is installed and available for all open systems and
mainframe asynchronous mirroring operations. Also consider the amount of Cache LUN XP
data to be stored in cache when determining the required amount of cache.
4. HP representative: Ensure that MCUs are configured to report sense information to hosts. RCUs
should also be attached to a host server to enable reporting of sense information if a problem
with an S-VOL or RCU occurs. If the remote site is unattended, RCUs should be attached to a
host server at the primary site, so the system administrator can monitor operational condition
of RCUs.
5. HP representative: If power sequence control cables are used, set the power select switch for
the cluster to LOCAL to prevent the host from powering off the MCU. Also ensure that the RCU
will not be powered off during XP Continuous Access operations.
6. HP representative: For Fibre Channel interface connections, install the Fibre Channel adapter
features. For serial interface connections, install the serial port adapter features. If the MCU
and RCU are multiplatform disk arrays, serial interfaces might be available, and additional
serial port adapter features might not be required.
34 Preparing for XP Continuous Access operations