Sun Microsystems Virtual Tape Library manual Storage path failover, Failover during replication

Key VTL features and options

Storage path failover

In a standard‐availability VTL system, there is one logical path from a VTL client to VTL storage, and every Fibre Channel port is either a target port for a VTL client or

astorage‐facing initiator. But in a high‐availability system, there are two paths, a primary and a secondary or standby path, as shown below.

Fibre Channel path failover in high-availability VTL systems

Primary server for A

Secondary server for B

Secondary server for A

WWPN x1	Primary path from A
	Secondary path from B

WWPN x2

VTL client A

Primary server for B

WWPN y1 Secondary path from A

		VTL client B
WWPN y2	Primary path from B

Failover during replication

If a replication operation is in progress when failover or failback occurs, replication stops. Once failover/failback has completed, replication resumes with the next normally scheduled operation.

Mirroring and failover

If mirroring is in progress during failover/recovery, after the failover/recovery the mirroring will restart from where it left off.

If the mirror is synchronized but Fibre Channel connectivity is lost between the server and storage, the mirror may become unsynchronized. It will resynchronize automatically after failover/recovery.

A synchronized mirror will always remain synchronized during a recovery process.

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