PM1643a

Abstract
The PM1643a Entry SAS 12Gb solid-state drives (SSDs) from Lenovo provide high-performance, reliable storage solutions for high-capacity enterprise applications. Designed for dense storage and with a 12 Gb SAS interface, these drives feature all the capacity and performance that is needed to replace large numbers of 15K rpm and 10K rpm spinning disks, and consolidate storage into tightly packed server configurations.

This product guide provides essential presales information to understand the PM1643a Entry SAS 12Gb SSD offerings and their key features, specifications, and compatibility. This guide is intended for technical specialists, sales specialists, sales engineers, IT architects, and other IT professionals who want to learn more about the SSDs and consider their use in IT solutions.

Introduction
The ThinkSystem PM1643a Entry SAS 12Gb solid-state drives (SSDs) are next-generation SSDs suitable for a wide range of applications. The PM1643a SAS SSDs are designed for dense storage and with a 12 Gb SAS interface, these drives feature all the capacity and performance that is needed to replace large numbers of 15K rpm and 10K rpm spinning disks, and consolidate storage into tightly packed server configurations.

The PM1643a SSDs are the follow-on to the PM1643 SSDs and offer improved random write performance.

Did you know?
Unlike SATA drives, the 12 Gb/s SAS interface on PM1643a drives supports full duplex data transfer for higher performance, as well as enterprise-level error recovery for better availability.

Rigorous testing of PM1643a Entry SATA SSDs by Lenovo through the ServerProven program assures a high degree of storage subsystem compatibility and reliability. Providing additional peace of mind, these drives are covered under Lenovo warranty.

SSDs have a huge but finite number of program/erase (P/E) cycles, which affect how long they can perform write operations and thus their life expectancy. Entry SSDs typically have a better cost per read IOPS ratio but lower endurance and performance compared to Mainstream or Performance SSDs.

SSD write endurance is typically measured by the number of program/erase (P/E) cycles that the drive incurs over its lifetime, listed as the total bytes of written data (TBW) in the device specification. The TBW value assigned to a solid-state device is the total bytes of written data (based on the number of P/E cycles) that a drive can be guaranteed to complete (% of remaining P/E cycles = % of remaining TBW).

Reaching this limit does not cause the drive to immediately fail. It simply denotes the maximum number of writes that can be guaranteed. A solid-state device will not fail upon reaching the specified TBW. At some point based on manufacturing variance margin, after surpassing the TBW value, the drive will reach the end-of-life point, at which the drive will go into a read-only mode.