Write cache protection in a purpose built backup appliance

1. A method for write cache protection in a purpose built backup appliance using a processor device in a computing environment, the method comprising:

upon data of the write cache being written to storage that is managed by a redundant array of independent disks (RAID) card, creating backup data of the write cache and preserving the backup data in a server memory that is managed through an operating system and not controlled by the RAID card;

flushing the backup data in the server memory to a persistent storage device subsequent to detecting a failure of the RAID card; and,

performing a reboot operation and, during the reboot operation, restoring the backup data to the storage managed by the RAID card from either the server memory or the persistent storage device, the purpose built backup appliance supporting an adapter hot swap of a RAID adapter card and the backup data being restored during the reboot operation from the server memory and not from the persistent storage device when the backup data is still active in the server memory.

2. The method of claim 1 , further including obtaining a lock for maintaining consistency of the backup data on the server memory, wherein the RAID card is at least one of a hardware RAID card, a software-based RAID card.

3. The method of claim 2 , further including, upon obtaining the lock, updating the backup data on the server memory for maintaining consistency of the backup data between the write cache and the server memory.

4. The method of claim 3 , further including releasing the lock upon achieving a successful update of the backup data on the server memory.

5. The method of claim 3 , further including performing one of:

invoking an error flush operation if the backup data is unable to be successfully updated, and

taking the purpose built backup appliance offline if the backup data is unable to be successfully updated on the server memory.

6. The method of claim 5 , further including performing one of:

issuing a fatal error message upon detecting a failure of flushing the backup data in the server memory to the persistent storage device, and

ensuring that a mirrored copy of the backup data residing on the server memory is flushed to the persistent storage device is a complete and consistent copy during the error flush operation.

7. The method of claim 1 , further including performing one of:

utilizing a user configuration setting for defining a desired behavior if the backup data is unable to be successfully updated on the server memory for allowing the purpose built backup appliance to continue to operate yet provide a user with a warning message indicating reduced data protection,

performing a consistency check of the backup data on the server memory in order to determine a best source for a required restore activity of the backup data, and

utilizing limited local server disk space in order to continue limited operations if there is one of a RAID adapter card failure and failure to access a RAID system by allowing currently running host jobs to complete rather than taking the purpose built backup appliance offline.

8. A system for write cache protection in a purpose built backup appliance of a computing storage environment, the system comprising:

at least one processor device operable in the computing storage environment for controlling the purpose built backup appliance,

wherein, upon data of the write cache being written to storage that is managed by a redundant array of independent disks (RAID) card, the at least one processor device creates backup data of the write cache and preserves the backup data in a server memory that is managed through an operating system and not controlled by the RAID card,

wherein the at least one processor flushes the backup data in the server memory to a persistent storage device subsequent to detecting a failure of the RAID card, and

wherein the at least one processes performs a reboot operation and, during the reboot operation, restores the backup data to the storage managed by the RAID card from either the server memory or the persistent storage device, the purpose built backup appliance supporting an adapter hot swap of a RAID adapter card and the backup data being restored during the reboot operation from the server memory and not from the persistent storage device when the backup data is still active in the server memory.

9. The system of claim 8 , wherein the at least one processor device obtains a lock for maintaining consistency of the backup data on the server memory, wherein the RAID card is at least one of a hardware RAID card, a software-based RAID card.

10. The system of claim 9 , wherein the at least one processor device, upon obtaining the lock, updates the backup data on the server memory for maintaining consistency of the backup data between the write cache and the server memory.

11. The system of claim 10 , wherein the at least one processor device releases the lock upon achieving a successful update of the backup data on the server memory.

12. The system of claim 10 , wherein the at least one processor device performs one of:

invoking an error flush operation if the backup data is unable to be successfully updated, and

taking the purpose built backup appliance offline if the backup data is unable to be successfully updated on the server memory.

13. The system of claim 12 , wherein the at least one processor device performs one of:

issuing a fatal error message upon detecting a failure of flushing the backup data in the server memory to the persistent storage device, and

ensuring that a mirrored copy of the backup data residing on the server memory is flushed to the persistent storage device is a complete and consistent copy during the error flush operation.

14. The system of claim 8 , wherein the at least one processor device performs one of:

utilizing a user configuration setting for defining a desired behavior if the backup data is unable to be successfully updated on the server memory for allowing the purpose built backup appliance system to continue to operate yet provide a user with a warning message indicating reduced data protection,

performing a consistency check of the backup data on the server memory in order to determine a best source for a required restore activity of the backup data, and

utilizing limited local server disk space in order to continue limited operations if there is one of a RAID adapter card failure and failure to access a RAID system by allowing currently running host jobs to complete rather than taking the purpose built backup appliance offline.

15. A computer program product for applying a content defined minimum size bound on content defined blocks using a processor device in a computing environment for write cache protection in a purpose built backup appliance, the computer program product comprising a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

a first executable portion that, upon data of the write cache being written to storage that is managed by a redundant array of independent disks (RAID) card, creates backup data of the write cache using a server memory that is managed through an operating system and not controlled by the RAID card;

a second executable portion that flushes the backup data in the server memory to a persistent storage device subsequent to detecting a failure of the RAID card; and

a third executable portion that, during a reboot operation, restores the backup data to the storage managed by the RAID card from either the server memory or the persistent storage device, the purpose built backup appliance supporting an adapter hot swap of a RAID adapter card and the backup data being restored during the reboot operation from the server memory and not from the persistent storage device when the backup data is still active in the server memory.

16. The computer program product of claim 15 , further including a fourth executable portion that obtains a lock for maintaining consistency of the backup data on the server memory, wherein the RAID card is at least one of a hardware RAID card, a software-based RAID card.

17. The computer program product of claim 16 , further including a fifth executable portion that, upon obtaining the lock, updates the backup data on the server memory for maintaining consistency of the backup data between the write cache and the server memory.

18. The computer program product of claim 17 , further including a sixth executable portion that performs one of:

releasing the lock upon achieving a successful update of the backup data on the server memory, and

invoking an error flush operation if the backup data is unable to be successfully updated.

19. The computer program product of claim 18 , further including a seventh executable portion that performs one of:

issuing a fatal error message upon detecting a failure of flushing the backup data in the server memory to the persistent storage device, and

ensuring that a mirrored copy of the backup data residing on the server memory is flushed to the persistent storage device is a complete and consistent copy during the error flush operation.

20. The computer program product of claim 15 , further including a fourth executable portion that performs one of:

utilizing a user configuration setting for defining a desired behavior if the backup data is unable to be successfully updated on the server memory for allowing a purpose built backup appliance to continue to operate yet provide a user with a warning message indicating reduced data protection,

performing a consistency check of the backup data on the server memory in order to determine a best source for a required restore activity of the backup data, and

utilizing limited local server disk space in order to continue limited operations if there is one of a RAID adapter card failure and failure to access a RAID system by allowing currently running host jobs to complete rather than taking the purpose built backup appliance offline.