> # 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:

> 1. Choose FICON > VSANs.

> You see the FICON VSANs dialog box.

> 2. Click the Director History button.

> You see the history buffer dialog box.

> 3. Click Close to close the dialog box.

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