I have a couple of questions about the m.2 slot, NVMe over PCIe, and general compatibility.
1. Can I use the Optane memories in an m.2 slot with M-keying?
2. How many PCIe lanes will be used? Will the number be affected by the m.2 slot keying?
3. Are there any official adapters to allow the use of the Optane with motherboards that don't have an m.2 slot?
Background and long version:
I want to use an Optane on a machine over USB 3.0, in front of an external storage disk. As I understand it from the documentation, the Optane memories use NVMe over PCIe, through a m.2 slot with B+M keying.
Most of the adapters I have found use either M-key (NVMe over PCIe only), or B-key (SATA bus). Some exist which allow adapting one or the other to USB 3.*, which is exactly what I need. As far as I can tell, no such adapters exist with both B and M keying. In fact, it seems like only SATA-based SSD drives use B+M keying, for compatibility reasons. I was hoping that the Optane series can use either keying without incident.
Another concern - Many of the adapters are expressly PCIe x4. The documentation states that either x2 or x4 is required, but offers no other restrictions. Assuming I picked an adapter that uses x4, is there any reason why it would not work as expected? Would the keying interfere with this? I'm assuming that M-keyed will have higher throughput due to the additional pins.
Are there any reasons why these would not work? Is there some other solution I've overlooked, which would allow me to use Optane in line with an external disk?
Hope this helps,
Thank you Scott,
A few followup questions:
1. The Optane has B+M keying, so it is compatible with both B and M keyed slots. That said, what determines how many PCIe lanes are used? Is it reconfigurable? If B uses 2 lanes and M uses 4 lanes, what does B+M use?
2. Per the FAQs here: https://www.intel.com/content/www/us/en/support/articles/000024018/memory-and-storage/intel-optane-m... https://www.intel.com/content/www/us/en/support/articles/000024018/memory-and-storage/intel-optane-m... the Optane can be used as a stand-alone disk using NVMe*. If I were to do so, would I be able to use an adapter from m.2 to USB? In this case, no redirection would be necessary.
Thanks for your help
The keying B+M means the Optane module can use either B or M configuration. BAsically, it will use 2 or 4 lanes. And the maximum lanes it will use is up to 4.
In the same FAQ you can find the following statement:
"You may use Intel® Optane™ memory as a standalone NVMe* SSD. However, we don't support this configuration."
This meaning that you can use the Optane memory as a stand alone disk. Intel has not tested or validated this specific configuration. Also, Intel does not test adapters to be used with our devices. Therefore you are free to try this configuration, however Intel will not test, validate or support this configuration. It may have unexpected behaviors.
Additionally, using the Optane memory with the NVMe protocol in the USB 3.0 interface will slower the device's speed and will not perform even near to the advertised speed.
Hope this information helps to clarify your questions, if you have any additional question please let me know.
I would add that almost all of the USB 3.0 drive bays that support M.2 SSDs support *only* M.2 SATA SSDs; they do not support M.2 NVMe SSDs.
I've noticed that as well, which is what led me to ask the question here in the first place. It appears that there is no such device to interface a device using PCIe lanes with one that does not. I can't seem to find that explicitly stated anywhere, but the lack of adapters supports that being the case.
Thank you Juan. I understand that this is a nonstandard use case and that you can't support it in any way. I appreciate the time you spent to help me just the same.
It was a pleasure for me to assist you with your questions.
Thanks for your patience and understanding about this issue.
If you have any additional question do not hesitate to open a thread and will be happy to help you.
The answers from Scott Pearson are right.
I will add some additional details.
- Intel does not test or validate the use of adapters on our SSDs including Intel® Optane™ Memory. Therefore there is not a list of validated components to achieve what you are trying to do.
- The Optane acceleration software (RST or the Optane UI) will not work recognize the Optane memory over USB.
Hope this information helps to clarify your questions. If you have any additional question please let me know.