HP XP7 Storage - Manual (Page 23)

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Master and restore journals are managed according to the journal ID.
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Review journal specifications in “System requirements” (page 15) .
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A journal can contain a maximum of 2 journal volumes.
Planning journal volumes
In addition to sizing journal volumes, you must also be aware of the following requirements and
restrictions.
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Only THP V-VOLs whose emulation type is OPEN-V can be used for journal volumes.
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Volumes in a virtual storage machine cannot be used as journal volume.
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A journal ID can be used in only one virtual storage machine.
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Volumes to which a path is set from a host cannot be registered as journal volumes.
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Journal volumes must be registered in a journal before the initial copy operation is performed.
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Journal volumes must be registered on both the primary and secondary systems.
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You can register two journal volumes in a journal in each primary storage system and secondary
system. Though two can be registered, only one is used (the first one registered). The second
is not used unless needed for maintenance, or to replace the first one.
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Journal volumes should be sized according to RPO and write-workload. See “Sizing journal
volumes ” (page 21) for more information.
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Journal volumes in a journal can have different capacities.
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A master journal volume and the corresponding restore journal volume can have different
capacities.
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The number of journal volumes in the master journal does not have to be equal to the number
of volumes in the restore journal.
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A data volume and its associated journal volume can belong to only one journal.
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Data volumes and journal volumes in the same journal must belong to the same controller.
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Do not register a volume to a journal during quick formatting. Doing so stalls the operation.
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Journal volume capacity is not included in accounting capacity.
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Journal volumes consist of two areas: One area stores journal data, and the other area stores
metadata for remote copy.
See the following for more information about journals and journal volumes:
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The “Journals” item in “System requirements” (page 15)
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“Planning journals ” (page 22)
Planning pair volumes
The following information can help you prepare volumes for configuration. Also, see system
requirements and specifications in
“Requirements and specifications” (page 15) for more information.
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The emulation and capacity for the S-VOL must be the same as for the P-VOL
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When the S-VOL is connected to the same host as the P-VOL, the S-VOL must be defined to
remain offline.
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When creating multiple pairs in the same operation, make sure that you set up S-VOL LUNs
in a way that allows the system to correctly match them to selected P-VOLs.
Even though you select multiple volumes as P-VOLs in the Remote Web Console Create Pairs
procedure, you are able to specify only one S-VOL. The system automatically assigns LUs on
the secondary system as S-VOLs for the other selected P-VOLs according to LUN.
Planning journal volumes 23