MM5425/256M Curtiss-Wright Battery-Backed PCI NVRAM Module

The MM-5425CN is designed to improve response time and data reliability in server appliances.

Especially Applicable to file servers and storage appliances that adhere to the NFS protocol or utilize journaling file systems, PCI NVRAM cards can enable there products to improve performance for I/O intensive applications and still comply with the industry standard benchmark, SPEC SFS.

SPEC SFS requires following the NFS Protocol, which ensures reliability by making many operations synchronous. While this is an excellent method towards guaranteeing reliability, there is an associated performance penalty. This penalty is greatest when hard disk drive(s) are selected as the stable storage device. the MM5425CN minimizes this performance penalty by replacing disk accesses with SDRAM memory accesses; SDRAM memory accesses are usually millions of times faster than disk accesses.

Unlike NVRAM that resides on a storage controller, PCI NVRAM can be completely controlled by the host that is also controlling the file system. In addition, PCI NVRAM provides superior performance to NVRAM on external storage controllers for synchronous writes because it is effectively accessed at the system level and only limited by the significant overhead of a cable interconnect.

Several journaling file systems now provide external journal mounts, so the journal log (metadata) can easily be placed on a separate device. Due to the nature of journal updates which often involve small, frequent writes where disk performance is at its lowest, a high speed PCI NVRAM card can be used as the device for the journal log.