NVMe or SATA SSD for Caching Tier

[elihuj]

I'm looking to build an All Flash Solution, and am evaluating what to use for my Caching Tier. Here's are the two that I've narrowed it down to:

• 1TB Intel P4500 NVMe
• Random Read: 294k
• Random Write: 32k
• Sequential Read: 3260 MB/s
• Sequential Write: 620 MB/s

• 960GB Intel P4600 SSD
• Random Read: 72k
• Random Write: 65k
• Sequential Read: 500 MB/s
• Sequential Write: 480 MB/s

I understand that with NVMe, I'll have a much lower latency. However, with it being my caching tier I'm concerned about the writes vs. the P4600 write-intensive SSD's. Another consideration is the NVMe's I'm looking at (due to cost) have a lower endurance rating than the 4600's.

So my question is are there any downsides in not using NVMe's for my caching tier outside of the lower latency that it brings?

[wreedMH · Accepted solution]

NVMe will have a larger queue depth that SATA, which could help some if the cluster becomes very busy, but looking at those specs, it would make me lean more towards the SATA drive with the higher write IO. An AF cluster the caching tier will be used only for writes, so one would think you would want a drive with better write performance.

Also read Intel description of the P4500, it is not made for writes.

Optimized for Storage Efficiency Across a Range of Workloads

This cloud-inspired SSD is built with an entirely new NVMe* controller, optimized for read intensive workloads, and designed to maximize CPU utilization.

I am sure someone will chime in with a better answer.

[wreedMH]

Look at the Toshiba SAS SSDs. We have lots of those are work and they smoke with vSAN.

Enterprise SSD | TOSHIBA Semiconductor & Storage Products | Americas

[GreatWhiteTec]

I will highly advise against SATA SSD for cache for many reasons. NVMe devices are great, but somewhat expensive. Depending on your performance need, you should consider SAS SSD or NVMe. If you must use SATA SSD, then you may use it for capacity , but even so, I will try to stay away from SATA protocol if at all possible.