HP XP P9500 Storage - Manual (Page 7)

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ESAM is used on open host systems only.
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An ESAM pair consists of a primary data volume (P-VOL) on the primary system and a
secondary data volume (S-VOL) on the secondary system (like Continuous Access Synchronous).
The S-VOL is the copy of the P-VOL.
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ESAM uses a quorum disk located on an external storage system, which keeps track of
consistency between the P-VOL and S-VOL. Consistency data is used in the event of an
unexpected outage of the data path or primary system. In this case, the differential data in
both systems is compared and, if the pairs are consistent, host operations continue on the
secondary system.
Hardware and software components
A typical configuration consists of two P9500 storage systems installed at the primary and secondary
sites. In addition, the ESAM system consists of the following components:
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ESAM and Continuous Access Synchronous software, which are installed on both systems.
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A host server running a multipath software solution, qualified with ESAM software, that is
connected to both storage systems.
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Dedicated Fibre Channel data paths linking the primary and secondary systems, with Fibre
Channel switches.
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A qualified external storage system to host the quorum disks. This storage system must be
accessible to both the primary and secondary storage systems.
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The following interface tools for configuring and operating the pairs:
Remote Web Console graphical user interface (GUI), located on a management LAN. ◦
◦ RAID Manager (RAID Manager), located on the host.
ESAM components are illustrated in the following figure and described in more detail in the
following sections.
Hardware and software components 7