I have a quick question on mass storage devices.
A hard drive, SSD, or USB thumb drive has a device name of /dev/sdX
such as /dev/sda, /dev/sdb etc. Partitions are /dev/sda1, /dev/sda2 etc
A M.2 M key NVME device has a device name of /dev/nvme0n1 then /dev/nvme0n2 etc
Partitions are /dev/nvme0n1p1 /dev/nvme0n1p2 etc.
Now the question, what device name does a M.2 B key SSD device have???
Pudge
I am not sure where to find out whether a drive is M or B but I have this drive https://www.newegg.com/samsung-970-evo-250gb/p/N82E16820147689
and it follows the behavior you are describing.
I’m not sure if it will use the same naming scheme as regular SSD as they use the same SATA port as opposed to m.2 NVME drives that use PCI-e bus?
Edit: Maybe i’m wrong here as the chart say’s the B key is also Pci-e
Thanks for your reply.
What you have is exactly what I have in three computers. It is a M.2 M key NVME SSD.
What I don’t have is hardware that has a M.2 B key SSD connector, nor do I have a B key storage device.
What I understand is, with a M.2 M key nvme device one can use it to install an Operating System on it and boot from it. I also understand that with a M.2 B key SSD you cannot boot from it, it is storage only. I believe it has something to do with the fact that M.2 devices were originally designed for Lap Tops. Not sure on that.
You can find more info on B key vs M key here HERE
@ricklinux
I believe you are correct, but if possible I need to know for sure.
With the diverse community we have here, hopefully someone will know for sure.
Pudge
I’m not entirely sure now? I have m.2 drives and they are the 2280 like this description.
WD Black SN750 500GB PCIe Gen3 x4 NVMe M.2 2280 Read:3470MB/s,Write: 2600MB/s SSD (WDS500G3X0C)
I see where he is going with this now after reading the link. He wants to use a usb m.2 nvme adapter card. I guess the question is how will linux see that device? A USB, NVME, or something completely different.
@ricklinux
The 2280 refers to the length of the M.2 drive, in this case 80 millimeters
Refer to the link I listed in the above post, then on the left, click on the 5th down little graphics display. It lists all the sizes available. Note that the shortest ones are both B key AND M key as they were originally designed for added storage in a Lap Top were size is crucial.
The B key PCIe is PCIe x 2 PCIe rails
The M key PCIe is PCIe x 4 PCIe rails and thusly is approx 2 times faster.
Pudge
Maybe I should explain what I’m doing here. I am working on a script that will auto partition, format and mount drives attached to the computer. I know from testing, that a HD, SSD, SSD nvme, or USB thumb drive works with the script.
What I don’t have is hardware with a M.2 B key connector for testing. So I am assuming, like @ricklinux that it will list the device as /dev/sdX but that is a guess.
By the way, I just used the M.2 converter on Amazon as a quick guide to M key vs B key. Be aware that most converters will NOT allow you to boot from them. Just FYI
Pudge
@Pudge
Okay…i see you are referring to a usb to m.2 adapter so i believe like i said before that it will use SATA port and possible be the same naming scheme /dev/sdx but i don’t know? It is using the usb port to connect but i’m thinking it will set up as a SATA device? I’m not 100% sure!
Is this what you are getting at?
Actually, I need to know what device name a M.2 B key would use either connected to the mother board OR from a M.2 converter as the M.2 B key to USB converter could be used as storage. I assume that either way (direct connect or USB connect) would use the same naming convention, which I assume is /dev/sdx
Pudge
That’s what i am thinking but i could be wrong. I assume as long as the motherboard will boot from usb it shouldn’t be an issue. Some boards don’t but i would say they are older hardware not the newer UEFI versions as most if not ALL should boot from usb. I realize you are needed the naming convention for your script. I just don’t know for sure I’m guessing?
Edit: The direct connect I would think if they are not using PCI-e bus would be SATA.
Edit 2: Ya i looked at the amazon link and it basically say’s it’s SATA.
Just to clarify. A USB device plugged directly into one of the computer’s USB ports should be capable to boot from. However, when you put a device, say a sata 2.5 inch SSD, into an enclosure or converter, you have added additional hardware to the pot. Namely a controller device inside the enclosure or converter that does the converting of protocols.
computer → USB port → storage device
computer → USB port → controller chip in enclosure or converter → storage device
With most enclosures and converters the controller chip in the enclosure does not support booting. Some will, but most don’t. The ones that will are usually more expensive.
Sorry to get off topic, I hope I’m not coming off as preaching, just passing on some info.
Pudge
I was more leaning towards worrying the usb connection would not boot on SOME computers which is fact. Internally i would have thought that it would be no different than any other drive whether it was m.2, ssd or SATA even if it was on a daughter board especailly with UEFI because of the way it’s supposed to work. You’re not preaching here… I’m just not sure as different manufacturers do different things with their BIOS, UEFI and Firmware so it’s one of those things. Some may not work or most maybe because i don’t really know for sure. I’m kind of guessing what i think but not sure. 