HP StorageWorks XP Remote Web Console Software - Manual (Page 99)

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The data which is copied to the TrueCopy for Mainframe M-VOL or Universal Replicator for
Mainframe P-VOL by Compatible Flash Copy V2 is asynchronously copied with the initial
copy operation to the TrueCopy for Mainframe R-VOL or Universal Replicator for Mainframe
S-VOL. Based on the speed of the data copy to TrueCopy for Mainframe R-VOL or Universal
Replicator for Mainframe S-VOL, the concordance rate of the TrueCopy for Mainframe pair
and Universal Replicator for Mainframe pair is calculated. According to the executing order
of the copy processing of the Compatible Flash Copy V2 relationship, the initial copy processing
of TrueCopy for Mainframe pair, the initial copy processing of Universal Replicator for
Mainframe pair, the executing of the TrueCopy for Mainframe or Universal Replicator for
Mainframe initial copy operation may be forced to wait. In this case, the concordance speed
of the TrueCopy for Mainframe or Universal Replicator for Mainframe pair may slow.
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If the delta resync operation interoperates with Compatible Flash Copy V2, use the delta
resync operation function which is supported for the remote command device function.
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The relationship of Compatible Flash Copy V2 can be created in the status under which the
TrueCopy for Mainframe initial copy operation can be executed. If the M-VOL of the TrueCopy
for Mainframe pair in the status of Duplex or the Pending duplex is assigned to the T-VOL of
the relationship of Compatible Flash Copy V2, the initial copy operation of TrueCopy for
Mainframe is executed. However, if the relationship of Compatible Flash Copy V2 is created
in the status under which the TrueCopy for Mainframe initial copy operation cannot be
executed, the TrueCopy for Mainframe pair may be suspended.
Planning for Journal Volumes
Why Planning is Necessary?
The data transfer speed for journal groups is affected by the specifications for the journal volumes
that the journal groups use. Therefore, you need to think about the specifications for journal volumes
to be used by journal volumes in order to achieve the data transfer speed that you want.
What to Consider for Planning
This section explains what you need to consider when deciding on journal volume specifications.
The following factors affect the speed for writing to and reading from journal volumes, particularly
when a temporary communication path failure occurs between the primary storage system and the
secondary storage system, or when the amount of data transferred from hosts to the primary storage
system is increasing:
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RAID configuration of the RAID groups that will contain journal volumes
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Types of physical volumes in the RAID groups that will contain journal volumes
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Frequency of access to non-journal volumes in the RAID groups that will contain journal volumes
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Data transfer speed required for the non-journal volumes mentioned above
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Disk usage rate for RAID groups
The following factor affects the time during which data transfer with hosts can continue without
being influenced by a temporary communication path failure between the primary storage system
and the secondary storage system, or without being influenced by an increase in the data to be
transferred from hosts to the primary storage system:
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Capacity of journal volumes
Computing the Required Data Transfer Speeds for Journal Volumes
The following figure illustrates how the data transfer speed (that is, the amount of data to be
transferred per unit of time) will change as time elapses, citing different types of data transfer
speeds with Universal Replicator for Mainframe. The data transfer speed between hosts and the
Planning for Journal Volumes 99