SSDs in IRST RAID 1 May Have Degraded Performance
Resumen: This article provides information about solid state drives in Intel Rapid Storage Technology RAID 1 experiencing degraded performance.
Síntomas
Degraded SSD RAID performance
You may notice that the read/write speeds of your solid state drives 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.
Causa
Resolución
No TRIM support in RAID 1 configurations
This is working as designed. The Intel Rapid Storage Technology (IRST) controller software does not include support for the Windows TRIM feature in RAID 1.
TRIM enables the SSD to handle garbage collection overhead. If TRIM is not enabled, it will 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 first requires 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 reduce the performance of the system over time. If you must 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 SSDs 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, contact Dell Technical Support.