Recovery (Install Only)

	NOTE: This section applies only to customer-created software with unpreinstall and unpostinstall scripts. HP-supplied software does not include these scripts.

SD-UX supports automatic procedures to recover from failed installation if the autorecover_product option is set to true, attempting to leave the system in the same state as it was previously. Also, manual means are available (refer to “Multiple Versions ”).

Rollback is limited to the system where the installation of the product failed, not all target systems specified in an installation job.

Because autorecovery removes any files that were installed up to this point, it is antithetic with the checkpointing and retry features previously described. Recovery saves copies of each file that it is replacing, then removes those files at the successful completion of the product installation. If the install fails, then the saved files are restored.

Once a product is successfully updated, it cannot be restored except by reinstalling it. Additionally, if a later product fails, the earlier product cannot be recovered. In order to meet the requirement that multiple products be recoverable, multiple versions must be installed.

The unpreinstall and unpostinstall scripts are needed to undo the steps that the preinstall and postinstall scripts executed. The normal sequence of operations for each product is:

If any of these steps fails (e.g., a lost source or a script error) then the undo scripts are run, and the files restored from the point of failure in reverse order.

	NOTE: Patches created using the features capabilities described may maintain saved files. In this case, patches can be removed (rolled back) or committed (by removing saved files). See Chapter 5: “HP-UX Patching and Patch Management” for more information on patches.The use of autorecover_product=true during an update of the HP-UX OS is not supported.