Failover, Pair status, Workflow for implementing esam – HP XP P9500 Storage User Manual
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Failover
A failover is an automatic takeover of operations from the primary system to the secondary system.
This occurs when the primary system cannot continue host operations due to a failure in either the
data path or the primary system. The multipath software in the host switches I/O to the remote
system. A multipath software package that has been qualified with ESAM must be installed on the
host.
Pair status
Pair status is an indicator of a pair's condition. The status changes when you perform an operation,
therefore you can check status to see if the operation completed. Also, pairs must have a certain
status for each operation.
The following provides a brief description of the ESAM pair statuses. See
for more detailed information about each status and how to monitor.
•
SMPL: A volume that is not assigned to a pair is in Simplex status, SMPL. Also, when a pair
is released, the status of both volumes changes back to SMPL.
•
COPY: When the initial copy is started, the status of the P-VOL and S-VOL changes to COPY.
•
PAIR: When a copy operation is complete, status of both P-VOL and S-VOL changes to PAIR.
•
PSUS: When you split a pair, the primary or secondary system changes the status of the P-VOL
and S-VOL to PSUS.
•
PSUE: When the primary system cannot keep the P-VOL and the S-VOL synchronized due to
an error condition, the statuses change to PSUE, which is pair suspended-error, split due to
an error. If the system cannot communicate with the secondary system, S-VOL status stays
PAIR.
•
SSWS: If a failover occurs in the storage system, S-VOL status changes to SSWS, and the
status of the P-VOL changes to PSUS.
•
SMPL: If you release the pair, the status of both volumes changes back to SMPL.
•
SSWS: If a failover occurs in the storage system, S-VOL status changes to SSWS, and the
status of the P-VOL changes to PSUS.
Workflow for implementing ESAM
The following shows a workflow for implementing ESAM and where to perform these tasks.
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External Storage Access Manager overview