How the SSI component works

The Storage Systems Integration (SSI) component is an XBM component that provides the following functions:

  • Snapshot processing by using intelligent storage DASD devices
  • An interface to allow active manipulation of storage devices
  • A monitor to show storage device status

Related topic

Snapshot-types-that-XBM-can-process

To perform a traditional hardware or Instant Snapshot, you must enable the SSI component. XBM requires this component to communicate to the supported hardware devices.

When you start the SSI component, either at initial startup of XBM or manually, it discovers the available intelligent hardware devices. The amount of time that the discovery process takes depends on the number of hardware devices you have. This discovery process determines the hardware snapshot capability of supported devices. For each device, the SSI component determines whether volume-level or data-set-level snapshots (or both) are allowed. The SSI component also passes this information to the SSI monitor, so that the XBM ISPF interface can display the hardware devices. Through the SSI monitor, you can issue commands to the hardware, such as displaying device information, establishing pairs, suspending pairs, and so on. (For more information about these commands, see Monitoring-and-managing-storage-devices.)

Important

  • The SSI component cannot access devices for which unit control blocks (UCBs) are dynamically added, changed, or deleted while the SSI component is running. When a device is dynamically added,  issues a message that warns you that you must restart the SSI component. The SSI component will not be able to recognize that device until it has discovered the UCB for the device during initialization. For information about restarting your SSI component, see Starting-and-stopping-components.
  • If you remove a device dynamically, the SSI component issues a message that indicates that the device was removed. XBM will no longer be able to obtain information about the device. The removed device will be ignored by the snapshot process and unavailable for any future requests.
  •  XBM supports alternate channel sets and the IBM HyperSwap function. When a HyperSwap is triggered to swap a primary device (which is attached to channel set 0) to a secondary device, the SSI component makes the primary device unavailable for use for Snapshot. In addition, XBM issues a message indicating that the primary device was removed. If a swap back is issued, you must restart the SSI component so that XBM displays the status of the device correctly and makes the primary device available.

To control whether the SSI component starts when the XBM subsystem starts, use the XSSI keyword in the XBM PROC (as described in Parameters). To start or stop the SSI component manually, use the procedure described in Starting-and-stopping-components.

SSI component options enable you to control how XBM processes the snapshots. These options control such things as whether to allow hardware snapshot and Instant Snapshots, as well as whether to perform volume-level or data-set-level snapshots. For more information, see Specifying-snapshot-types-through-options.

XBM provides commands that allow you to set some commonly used vendor-specific hardware device options. For more information, see Commands-for-managing-SSI-options.


 

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