I've got at work Dell R730xd with 6 NL-SAS 7200RPM 8TB Drives in RAID10. Is was fine for what we use it - hyperv and main storage. OS is Server 2012R2 DC with about 20 VM. 1 of those is around 2TB bit and uses DFS. Recently i looked at perfmon and after a bit heavier work for example i've noticed queue lenght as big as 4.0. Ive started VM in that time. Normally its around 0.020-0.100. Should i start to worry about latency and/or IOPS? It crossed my min to purchase PCIe NVME as a cache. At home i've got S3500 and i've noticed that Intel SSDs has dedicated cache software. Iwas thinking about Intel 750, P3500 or P3600 as such cache device. Is anyone used PCIe as a cache device ? Is it safe ? The issue with PCIe drives is that there is really no method to raid other than software. Or perhaps maybe Intel are that good that raid1 for that drives is not needed and good backup is enough ? Thanks in advance for suggestions!