Solid State Drives in IRST RAID 1 may have degraded performance

Solid State Drives in Intel Rapid Storage Technology RAID 1 (Mirror) configurations may have degraded performance over time. This article provides more information on this issue and troubleshooting guidance.

Degraded SSD RAID performance.

You may notice that the read/write speeds of your Solid State Drives (SSD's) in a RAID 1 configuration degrade over time. If the operating system is reinstalled or the system is re-imaged the problem is temporarily resolved.

No TRIM support in RAID 1 configurations.

This is working as designed. The Intel Rapid Storage Technology (IRST) controller software doesn't include support the Windows TRIM feature in RAID 1.

TRIM enables the SSD to handle garbage collection overhead, if TRIM is not enabled it will significantly slow down future write operations to the involved blocks.

The process of garbage collection involves reading and rewriting data to the flash memory. This means that a new write from the host will first require a read of the whole block, a write of the parts of the block which still include valid data, and then a write of the new data. This can significantly reduce the performance of the system over time. If you need to confirm that TRIM is the cause of write speed degradation on an SSD in a RAID 1, you can re-image the drive (outside of the RAID volume) and re-test the write speed. Expected writes speeds for all SSD's vary dependent on the model.

NOTE: TRIM is supported in IRST for RAID 0 (Striped Array), and also in RAID 1 in IRST for Enterprise on Dell Precision Workstations which support this IRST for Enterprise version.

If you need further assistance with this issue, use the following link to contact Dell support: Contact Dell Technical Support.