Administrator Guide

– Replication status is Synchronized.
– Write mode is either Synchronous or Asynchronous, depending on your selection above.
– The secondary virtual disk is either write consistent/not write consistent.
– Resynchronization method is either Manual or Automatic.
Resynchronizing Virtual Disks
There are two resynchronization methods for remote replications:
• Manual resynchronization — See Manually Resynchronizing Virtual Disks.
• Automatic resynchronization — See Automatically Resynchronizing Virtual Disks.
For more information about synchronization and resynchronization in remote replications, see:
• Normally Synchronized Virtual Disks.
• Unsynchronized Virtual Disks.
• Setting Synchronization Priority And Synchronization Method.
• Changing Synchronization Priority And Method.
• Resynchronizing Virtual Disks.
You may require to periodically test the communication between the primary virtual disk and the secondary virtual disk
in a remote replication, especially after resynchronizing virtual disks. For information about testing the communication,
go to Testing Communication Between The Primary And Secondary Virtual Disks.
Normally Synchronized Virtual Disks
In a normally synchronized remote replication, RAID controller module owners manage the transfer of data from the
primary to the secondary virtual disk. In a normal remote replication, these events occur:
• The primary virtual disk receives a write request from a host.
• The RAID controller module owner on the storage array logs information about the write operation to a
replication repository virtual disk in the storage array.
• The RAID controller module owner writes the data to the primary virtual disk.
• The RAID controller module owner starts a data transfer operation to the secondary virtual disk on the
secondary storage array.
The communication between a primary and secondary virtual disks can be suspended or become unsynchronized. If
communication between the primary virtual disk and the secondary virtual disk is disrupted:
• The status of the replicated pair changes to Unsynchronized.
• A Needs Attention status is displayed for the storage array.
• Data is written to the primary virtual disk.
• Write requests to the primary virtual disk are logged.
• The RAID controller module owner sends an I/O completion message to the host sending the write request.
Although the host can continue to send write requests to the primary virtual disk, no data transfer takes place to
the secondary virtual disk. Writes to the secondary virtual disk are suspended pending restoration of
communications between the primary virtual disk and the secondary virtual disk.
When connectivity is restored between the primary virtual disk and the secondary virtual disk, the replicated pair is
ready to be resynchronized.
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