MM-5453CN

2GB PCI Express x4 Low Profile NVRAM Card

• Capacity: 512MB, 1GB & 2GB
• PCI Express x4 interface
• Application optimized Mailbox DMA for chaining linked-lists
• Device Drivers available for several operating systems
• Error Detection and Correction
• Specialized, low latency DDR memory controller
• Supports Interrupts
• Field replaceable battery mezzanine
• Low-Profile, Half-Length PCI card form factor

** Tier I/II OEM Product **
The MM-5453CN is an OEM product not available for purchase through distribution channels.

The Umem MM-5453CN is a PCI-Express x4 NVRAM card with battery backup. It has been engineered to speed up response time and improve data availability in enterprise-class server and storage appliances.

The MM-5453CN is based on a PCIe x4 interface. The host can access it as a peripheral device by way of a serial interconnect through a PCI Express switch fabric subsystem. PCIe fabrics offer users the advantage of accessing multiple peripherals concurrently. Compared to more traditional parallel buses, such as PCI-X, the MM-5453CN—operating as a serial interconnect—enhances signal integrity over higher clock frequencies.

PCI Express is backwards compatible to PCI at the device driver level. The MM-5453CN provides a seamless transition to high speed serial technology and helps users protect their software investments as it maintains the same register set and DMA functionality as its PCI Umem predecessors.

Ultimate Random Access Performance
The MM-5453CN, equipped with up to 2GB of DDR memory, is especially well suited for high throughput operations and continuous random access—qualities possible only with solid state RAM. While the drawbacks of using hard disk drive technology for random access operations are understood, other solid state drives (SSD)—including those based on Flash memory technology—also pose problems.

Flash SSDs Not the Answer
Flash is non-volatile, but operates with significant latency while pages or blocks are "flashed" to memory. Techniques arraying large numbers of Flash devices are used to mitigate this weakness. But while this technique improves throughput, it accomplishes little toward enhancing real IOPS. This is especially the case for bursts that exceed the memory's Flash page size, which Flash SSD marketing material commonly misrepresents.

Flash memory has limited lifetime write/erase cycles, so SSDs apply wear-leveling algorithms to raise the limit of accesses over time. This practice introduces overhead as a virtual file system serves as an intermediary between I/O operations and memory accesses. Compounding these performance limitations are bad blocks, a common fault of NAND Flash that increases in frequency over time. Bad block mapping algorithms are thus implemented. These often involve reading pages before writing, a process that further slows response time for random and even sequential operations.

Proprietary Data Retention Technology
To avoid these performance issues, Umem cards use DRAM—not Flash memory. Umem NVRAM cards are limited only by the peripheral interconnect—PCI Express—not the memory media. However, DDR, unlike Flash, is volatile and thus requires continuous, uninterrupted power to retain data. However, through proprietary data retention technology refined by Curtiss-Wright over the course of 25 years, the volatile DDR memory is transformed into persistent storage on Umem cards. Through this technology, the memory can reliably maintain data through a myriad of abrupt power failures and system panics.

Compact Form Factor
The MM-5453CN's compact form factor is consistent with the PCI-SIG specification for low profile, mid-length options and ideally fits in tightly integrated appliances. This integrated configuration is designed for the PCI single card slot envelope. An FRU mezzanine, mounted to the MM-5453CN, can contain up to three rechargeable lithium-ion batteries.

Low-Latency Controller
The MM-5453CN's specialized, low-latency DDR memory controller and application-optimized DMA engine provides performance characteristics such as scatter-gather capabilities, chaining of linked lists and semaphore updates to minimize system overhead.

The Key to Cutting-Edge File Systems
Controlled by the system host, Umem NVRAM cards maximize and differentiate file system performance. Umem technology enables implementation of specialized file system operations, data protection, advanced features and availability functionality—applications that would otherwise incur prohibitive performance penalties.

State-of-the-art proprietary file systems of enterprise-class appliances depend on battery-backed NVRAM to enhance the performance of certain operations—such as those that involve checkpoints and inode updates. NVRAM technology ensures that these file systems can be logged to stable, high-speed, random access storage in an ordered fashion that avoids the penalties typical of other forms of stable storage.

Another advantage of Umem NVRAM cards: They enable application specific write-caching under the intelligent control of the host. And this can be done in conjunction with software RAID and file system journaling, which is not possible with the NVRAM of a conventional RAID controller.

Umem NVRAM Cards for NFS
Umem cards enable file servers and storage appliances that adhere to the NFS protocol to improve performance for I/O intensive applications while complying with the industry standard for NFS—SPEC SFS.

SPEC SFS requires that NFS protocol be followed to ensure reliability, making many operations synchronous. These operations typically involve journal logs and metadata, directory and inode updates, database snapshots, time stamps, cluster checkpoints, and changes to actual file data.

Making operations synchronous and requiring that they be committed to stable storage are excellent ways to help guarantee reliability. But there is a performance penalty to pay when hard disk drives or Flash SSDs are selected as the stable storage device.

Umem PCI NVRAM cards help reduce the risk of this penalty and response time by replacing disk accesses with memory accesses. Unlike system memory, however, the Umem cards provide on-board battery back-up to support data retention and prevent reinitialization of memory in a power up or system reset. These Umem cards ensure compliance with NFS protocol and SPEC SFS requirements for stable storage. More generally, they ensure high availability for enterprise-class appliances.