SSDs are like traditional magnetic storage based hard drives in that data still resides on the drive after it has been deleted by the OS. That data block is overwritten by new data when the amount of fresh unused storage is depleted. On most SSDs, data is erased in 512KB blocks even though data is written in 4KB pages. This means that if a single 4KB page needs to be updated, the whole block must be erased and rewritten, slowing down the drive significantly. This is particularly true for random write operations.

TRIM synchronizes the operating system's view of deleted files with those that are deleted, but not yet erased on the hard drive. SSD controllers are good at managing data, but they have no optimization for different file systems. TRIM lets the controller know that data has been deleted so that it can wipe the entire block when it is not busy with other operations. This significantly speeds up write operations, especially when the drive is nearly full.

Intel's second generation X25-M series SSDs have been selling very well, and the company has been promising TRIM support to its many customers. It is releasing new firmware to the public that will enable the use of TRIM, but only with its latest generation of mainstream SSDs using 34nm NAND flash.

"Fast and reliable access to data is critical for our SSD users," said Pete Hazen, Director of Marketing for Intel's NAND Solutions Group. "The latest firmware and toolbox upgrade for Intel 34nm SSD users provide a host of new management, information and diagnostic tools to help SSDs retain out-of-box performance. We are encouraging our 34nm customers to download the new firmware update today. Not only will Windows 7 users receive the performance enhancements of the Trim command, but so will our Windows XP and Vista
users."

Owners of second generation 160GB X25-M drives running Windows 7 will also see a 40 percent performance boost to sequential write speeds. The firmware update allows the drives to write data at up to 100MB per second.

Backing up data before the firmware update is highly recommended, but existing data on the SSD will not be erased. Intel also cautions against using the firmware utility over RAID, as each drive must be flashed individually. The firmware update is available here.

TRIM has been implemented in Linux 2.6.28 since December of last year. All older solid state drives will need firmware updates to enable TRIM support, otherwise the new command will be ignored by the controller.