Dell Technologies Server Troubleshooting Guide

Certain operating systems support the TRIM function, which translates deleted files to the associated LBA (logical block address) on the storage device (SSD). For SATA, the command is referred to as TRIM, for SAS, the command is called UNMAP. The TRIM or UNMAP command notifies the drive that it no longer needs data in certain Logical Block Addresses (LBA) which then free up several NAND pages.

The TRIM or UNMAP command must be supported by the operating system, the drive, and the controller in order to work. The TRIM or UNMAP command could result in higher SSD performance from both the reduced data needed to be rewritten during garbage collection and the higher free space resulting on the drive. Dell enterprise drives which are currently shipped have high performance and endurance so they do not yet support these commands even if the OS supports them. These features are being investigated for subsequent Dell SSD offerings.