Features

The PM1635a Enterprise Mainstream 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
• Active-active dual port host 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

Enterprise Entry SSDs and Enterprise 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). Enterprise Mainstream SSDs have better endurance but lower cost/IOPS ratio compared to Enterprise 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 does not fail upon reaching the specified TBW, but at some point after surpassing the TBW value (and based on manufacturing variance margins), the drive reaches the end-of-life point, at which time the drive goes into read-only mode. Because of such behavior, careful planning must be done to use SSDs in the application environments to ensure that the TBW of the drive is not exceeded before the required life expectancy.

For example, the PM1635a 1600 GB drive has an endurance of 8760 TB of total bytes written (TBW). This means that for full operation over five years, write workload must be limited to no more than 4800 GB of writes per day, which is equivalent to 3.0 full drive writes per day (DWPD). For the device to last three years, the drive write workload must be limited to no more than 8000 GB of writes per day, which is equivalent to 5.0 full drive writes per day.

Technical specifications