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Configuration: Premium Feature— Remote Replication 199
Unsynchronized Virtual Disks
Communication between a primary and secondary virtual disks can be either
suspended, or become unsynchronized. If this communication between both
virtual disks is disrupted:
1
The status of the replicated pair changes to
Unsynchronized
.
2
A
Needs Attention
status is displayed for the storage array.
3
Data is written to the primary virtual disk.
4
Write requests to the primary virtual disk are logged.
5
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
and secondary virtual disks.
When connectivity is restored between the primary and secondary virtual
disks, the replicated pair is ready to be resynchronized.
NOTE: When the primary virtual disk and the secondary virtual disk are
resynchronized, only data that has changed on the primary virtual disk after the
break in communication is transferred to the secondary virtual disk.
CAUTION: Loss of data can occur if communication is broken after
resynchronization starts between the primary storage array and the secondary
storage array. In addition to resulting in an incomplete resynchronization that may
render the secondary storage array unusable, an interrupted resynchronization
could cause a loss of data integrity on both arrays.
book.book Page 199 Wednesday, June 8, 2011 5:01 PM