Viewing the History Buffer
In the directory history buffer, the Key Counter column displays the 32-bit value maintained by Cisco MDS switches. This value is incremented when any port changes state in that VSAN. The key counter (a 32-bit value) is incremented when a FICON-related configuration is changed. Host programs can increment this value at the start of the channel program and then perform operations on multiple ports. The director history buffer keeps a log of which port address configuration was changed for each key-counter value.
The director history buffer provides a mechanism to determine the change in the port state from the previous time when a value was contained in the key counter.
To view the directory history buffer using Device Manager, follow these steps:
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