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Umem Applications

Curtiss-Wright has specialized in designing and manufacturing battery backed RAM cards for open industry standard bus architectures. This has involved pioneering a myriad of data retention features and over twenty-five years of refining the battery failover circuitry for use in enterprise products and high availability solutions.

Especially applicable to file servers and storage appliances that adhere to the NFS protocol or utilize journaling filesystems, Umem cards enable these 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. These operations typically involve directory and inode updates, journal logs and metadata, data base snapshots, cluster check points, time stamps and changes to actual file data.

Specifically, this means that when a client issues a synchronous write or commit request to the server/storage appliance, the server cannot reply back to the client that the request has been received until the write has been committed to stable storage. This can also prevent the client from initiating new requests until it receives the required acknowledgment. As most networks have several clients, this can easily create a bottleneck in terms of response time.

While making operations synchronous and requiring they be committed to stable storage 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.

Umem PCI NVRAM cards minimize this penalty and response time by replacing disk accesses with memory accesses; SDRAM memory accesses are generally several million times faster than any hard disk drive. But unlike system memory, the Umem cards uniquely provide on-board battery back-up that enables data retention and prevents re-initialization of memory upon power up or system reset, complying with the NFS protocol and SpecSFS requirements for stable storage.