HP XP P9500 Storage - Manual (Page 15)

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Only external storage systems supported by External Storage can be used for the quorum
disk. For a list of supported external storage systems, see the HP P9000 External Storage for
Open and Mainframe Systems User Guide.
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Multiple quorum disks can be created in one external storage system.
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The maximum number of quorum disks per external system is 128.
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The external system is not required to be dedicated to quorum disks exclusively.
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Quorum disk size requirements: 47 MB to 4 TB (96,000 blocks to 8,589,934,592 blocks).
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The quorum disk must not be expanded or divided by LUN Expansion or VLL.
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An LU path must not be configured to the quorum disk.
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Read/Write operations from the storage system to the quorum disk are for internal use. These
operations are performed even when Write Pending operations reach 70%.
CAUTION: Quorum disks are used in a unique way in that they are shared with two storage
systems. For data protection reasons, make sure not to share any other kind of volume with two
storage systems.
Data path requirements and recommendations
Data is transmitted from the P-VOL to the S-VOL over the data path. Please observe the following
requirements and recommendations:
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Data path requirements for ESAM are the same as Continuous Access Synchronous
requirements. See the HP P9000 Continuous Access Synchronous User Guide.
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Do not share the data paths with Continuous Access Synchronous. Install independent data
paths for ESAM.
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Install at least two data paths from the primary system to the secondary system, and two data
paths from the secondary system to the primary system. This allows data transfer to continue
in the event of failure of one path's cables or switches.
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Optical fibre cables are required to connect the primary and secondary system.
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Direct and switch connections are supported.
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Use target ports in the primary and secondary systems to connect with the host Fibre Channel
ports.
Initiator ports cannot be used for host connections. See the section on configuring host interface
ports in the HP P9000 Continuous Access Synchronous User Guide for information about port
attributes.
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The following table shows maximum, minimum, and recommended number of data paths,
logical paths, and ports for ESAM.
Table 1 Data paths, logical paths, ports required
Recommended Max. Min. Item Category
2 or more 4 1 Path between primary/secondary systems and a
host. Physical Data
Paths
2 or more 8 1 Data path from primary to secondary system.
2 or more 8 1 Data path from secondary to primary system.
2 or more 8 1 Path between primary/secondary systems and
quorum disk.
2 or more 8 1 From primary to secondary system. Logical Paths
Data path requirements and recommendations 15