HP StorageWorks XP24000 Continuous Access Software User and Reference Guide, v01 (T5278-96002, June 2007)

If the Continuous Access S-VOLs and P-VOLs are connected to the same host(s), H P strongly recommends
that the S-VOLs be defined to remain offline to avoid this problem.
Host System Cr ash
The contents of the P-VOL and S-VOL of a Continuous Access pair may become inconsistent if the host
system hangs (crashes) while a write operation is being performed on the Continuous Access P-VOL, and
the
write operation cannot be retried be cause of the following reasons:
• A check condi
tion is reported to the host d ue to a failure in the storage system when the write
command for t
he Continuous Access pair is issued.
• A reset command is issued from the host and the write operation is stopped (the write op eration
is
incomplete).
If these con
ditions occur, you must retry the job to complete the write operation.
Installing the Hardware
Initial installation of the Continuous Access hardware is performed by the user and the HP service
representative. The hardware configurations for Continuous Access Synchronous and Continuous Access
Asynchronous are the same.
To install the hardware required for Continuous Access operations:
1. User: Identify the locations of the Continuous Access primary and secondary volumes (P-VOLs
and
S-VOLs), so that the Continuous Access hardware can be installed and configured properly.
2. HP Service Representative: Make sure that the MCU(s) and RCU(s) a re configured for Remote
We b Console operations (for example, SVP connected to LAN). See the HP StorageWorks
XP24000 Remote Web Console User’s Guide for information and instructions on setting up
Remote Web Console operations.
3. HP Service Representative: Make sure that the MCUs and RCUs are properly
configured for Continuous Access operations (for example, cache and NVS) (see
“Cacheand NonvolatileStorage (NVS)” on page 45). Make sure that the desired system option
modes are enabled (see “Storage Systems” on page 14). Make sure that adequate cache is
installed and available for asynchronous operations (Continuous Access Asynchronous and CC).
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 Service Representative: Make sure the MCUs are configured to report sense information
to the host(s) . The RCUs should also b e attached to a host server to enable reporting of sense
information in case of a problem with an S-VOL or RCU. If the rem ote site is unattended, the
RCUs should be attached to a host server at the primary site, so that the system administrator
can
monitor the o perational cond ition of the RCUs.
5. HP Service Representative: If power sequence control cables are used, set the power select
switch for the cluster to LOCAL to prevent the MCU fro m being powered off by the host.
Also make sure the RCU will not be powered off during Continuous Access operations. See
“Powering Off/On Continuous Access Components” on page 124 for further information on
powering off/on the MCUs and RCUs.
6. HP Service Representative: Install the Fibre Channel adapter features (for example,
DKC-F510I-32FS2 and DKC-F515I-MIX2). Please see the Installation section of the DKC6101
Maintenance Manual for further information.
Note: For DKC-F510I-32FS2 and DKC-F515I-MIX2, you can set each port independently as an
initiator or RCU Ta rget port, enabling you to connect hosts and remote links randomly.
7. HP Service Representative: Install the Continuous Access remote copy connections between the
MCU(s) and
RCU(s). This hardware (optical fibre cables, switches, and so on) is supplied by the
user. See “Remote Copy Connections”onpage47for remote copy configurations. Distribute
the paths
between different storage clusters and switches to p rovide maximum flexibility and
availability. The logical paths between the MCU and RCU must be separate from the logical
paths
between the host and RCU. All remote copy activities between two storage systems (that
is, Continuous Access Synchronous, Continuous Access Asynchronous, TrueCopy Synchronous
46
Preparing for Continuous Access Operations