When I/O is going to a mirrored virtual disk and both DataCore Servers are stopped,
a full recovery may be required. See Mirroring
and Mirror Recovery for more information about mirror recovery.In this topic:
When a DataCore Server is stopped in the SANsymphony software, virtualization is stopped and the server is taken offline, but does not remove the server from the configuration.
While a server is stopped:
o DataCore device drivers are stopped. Ports that are set to Target Only are disabled; this includes ports with only the FE role set, iSCSI target mirror ports and Fibre Channel mirror ports set to Target Only.
o The cache is flushed.
o Some configuration changes can be made in the management console when a server is stopped, but operations requiring drivers (such as virtualization) can not be performed or will not take effect until the server is started again.
o Front-end paths between
the host and server are set offline. All mirrored virtual disks with active
paths using the DataCore Server
will failover to the other server in the server group. (When the server
is restarted, the paths will failback.)
When I/O is going to a mirrored virtual disk and both DataCore Servers are stopped,
a full recovery may be required. See Mirroring
and Mirror Recovery for more information about mirror recovery.
o All single virtual disks will be inaccessible to the host.
When stopping a server is required:
o When the cache settings for a server are changed, the settings will not take effect until the server has been stopped and then restarted.
o It is a best practice to stop virtualization on the server before shutting down a server or when performing server maintenance operations which will require a computer restart. This is known as a "clean" or "graceful" shutdown.
To stop a server:
1 In the DataCore Servers Panel, right-click the server to stop and select Stop DataCore Server.
2 Click Yes on the confirmation message to continue.
After stopping a server, the server will have to be started again to resume mirroring and allow storage to be served from the server.
To start a server:
In the DataCore Servers Panel, right-click the DataCore Server to start and select Start DataCore Server.
Certain behaviors can be observed when DataCore Servers are restarted:
o When a DataCore Server machine is intentionally restarted (such as after a computer shutdown or computer restart), SANsymphony software will restore the last state of the DataCore Server. So if the server was "started" in the software when the machine was restarted, then the server will be "started" in the software after the machine comes back up.
o When a DataCore Server machine restarts unexpectedly (such as in a power failure), the DataCore Server will come up "stopped" in the software as a precaution. By design, virtualization will not be started automatically, so that the administrator can check in the console that all storage-related hardware components and mirror port connections are up and reconnected to targets. Once this has been established, then virtualization can be manually restarted (using the instructions below).
o
When more than one DataCore Server
is stopped (intentionally or unintentionally), the server that was the
last to go down or the last "stopped" will have the latest known
status of a mirrored virtual disk.
· Until all servers with mirrored virtual disks are restarted, the state of mirrored virtual disks will be unknown and host access will be disabled. After starting the servers, in most cases the software will be able to determine any recoveries that need to take place and begin them in the correct order. However, if the virtual disk status is still unknown, data access can be restored by following the Force Mirror Recovery procedures.
· When restarting servers with mirrored virtual disks, the best practice is to start virtualization on the last server that was stopped (if known), before starting virtualization on the other servers. For example, if two servers are powered down, here is the recommended sequence: (1) stop DataCore Server 1 and shut down DataCore Server 1, (2) stop DataCore Server 2 and shut down DataCore Server 2, (3) power up DataCore Server 2 and start DataCore Server 2, (4) power up DataCore Server 1 and start DataCore Server 1.