During a non-disruptive software update or a software fault to the Controller nodes, warmstarts can occur.
A warmstart is a soft reset (not a reload) of the operating system in a Controller. During a Controller warmstart, the data structures for the operating system are reinitialized and all customer data is kept intact. The warmstart appears as a target reset to the SAN host, which causes all outstanding SCSI commands to be retried by the host. A warm start continues to process all data already in the Oracle FS System.
As each Controller node warmstarts, a temporary protocol service disruption of a few seconds can occur on each node. This disruption is typically non-disruptive to most applications and protocols. If more than four warmstarts occur in an hour, the Controller node fails over, reloads the operating system, and then rejoins the system.