Lenovo ThinkSystem 3.5" PM1645A 6.4TB Mainstream SAS 12Gb Hot Swap SSD

The PM1645a Mainstream SAS 12Gb SSDs have the following features:

• Mainstream server SSD suitable for mixed read-write-intensive workloads
• Endurance of 3 drive-writes per day (DWPD)
• 2.5-inch or 3.5-inch industry standard form factor with hot-swap tray
• SAS 12 Gbps interface
• Protect data integrity from unexpected power loss with Samsung's advanced power-loss protection architecture
• Supports Self-Monitoring, Analysis and Reporting Technology (S.M.A.R.T)
• End-to-end data protection
• Support 16 Initiator with Tag Command Queuing (TCQ) Command Set with a queue-depth of up to 128 commands
• Compliant with SCSI Specification (SAS-3 / SPL-3 / SBC-4 / SPC-4 / SAM-5)
• RoHS Compliant

Entry SSDs and Mainstream SSDs have similar read and write IOPS performance, but the key difference between them is their endurance (or lifetime) (that is, how long they can perform write operations because SSDs have a finite number of program/erase (P/E) cycles). Mainstream SSDs have better endurance but lower cost/IOPS ratio compared to Entry 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.