Method to reserve part of a disk controller's battery backed up cache for data that is not to be flushed to disk but instead is held across system boots in the cache
Publication Date: 2010-Sep-22
The IP.com Prior Art Database
Disclosed is a method to use the battery backed up disk controller cache instead of adding a NVRAM card to store data for a point-of-sale (POS) operating system. The invention requires that a disk controller that has a battery backed-up cache dedicate a portion of the cache, which is not flushed but instead holds the data, for use by the POS operating system.
Method to reserve part of a disk controller 's battery backed up cache for data that is not to be flushed to disk but instead is held across system boots in the cache
In order to be more stable and avoid lost data, a point-of-sale (POS) operating system well-used in the retail industry requires the installation of a nonvolatile random access memory (NVRAM) card. The first use of NVRAM is to keep a copy of local disk writes in the event that power to the system is lost before the data is written to the disk platter. The NVRAM card is used to store that valuable data. When the system recognizes that the data is successfully written to disk or distributed to other POS Controllers, the system deletes/invalidates the data from the NVRAM. Another use of NVRAM is to keep a record of where on the disk data written locally is located in the event that the data is needed due to a failure in data distribution to other controllers. Other uses of NVRAM include: storing the controller's name, keeping lock record information and other items that are faster accessed from NVRAM rather than from the disk platter, helping with data integrity, and aiding performance so applications are not waiting for data to be distributed to other systems or waiting for data.
To improve efficiency, a method is needed to remove this requirement for a physical NVRAM card while ensuring that:
• data is never lost in the event of a power failure
• the POS data distribution has fast performance
• POS operating system code does not require developers to do a considerable amount of re-writing
The problem is that for newer systems (System x) and blade servers, the existing Retail Store Solutions' (RSS) NVRAM cards are the wrong form factor or are peripheral component interconnect (PCI) cards and the new servers only have PCI-e slots. It is expensive to make a new card that will fit both newer System x and blade servers. It is also costly to update device drivers to include support for the new NVRAM card.
The proposed solution is to use the battery backed up disk controller cache instead of adding an NVRAM card. The System x and blade servers have options to include a battery backed up disk controller cache. The battery backed up cache is an additional feature on the disk controller and does not utilize an extra PCI or PCI-e as does a NVRAM card. A battery backed up cache is functionally equivalent to NVRAM. No new NVRAM cards in different form factors and with different connectors for PCI/PCI-X/PCI-E/CIO-v need to be made, and the NVRAM driver does not need to be updated and re-tested for this new form factor/connection type. Code would need to be written so that the operating system could map the disk controller cache and use the disk controller cache as it uses NVRAM now. Writes that would normally go to NVRAM would go to the battery protected disk cache directly and would execute faster than going to the actual disk platter. If power was lost and the data in the c...