NVME or M.2 to PCIe Bifurcation

[hunter69]

I have been researching Bifurcation.  I am looking for technicalities to watch out for including suggested adaptors.  I emailed Asrock and confirmed my board supports 8x8 & 8x4x4.  So what does this mean, does it mean I could have either a 2 port adaptor running the nvme at 8x8 or a 3 port adaptor running at 8x4x4?  I probably am not quite understanding the concept yet.  

 

I have read there are raid and not raid adaptors, can a person use either.

 

My end goal is to protect my cache that has my dockers and vm's.

 

Currently I have 2 m.2 cache drives.  1 for normal cache.  1 for dockers and vm's.

 

Thanks for the information in advance

[MAM59]

No, it means that the existing 8x slot (ususally the 2nd one?) can either be used as 1*8x or can be switched to 2*4x.

So you could either use a cheap 1port adaptor (they only use 4 lanes then) or a cheap 2port adapter (or more, but only 2 devices will be available then).

 

With "cheap" I mean those cards without any electronics. These are usually 10-20€ each.

 

The "raid" cards that you have read of have an own PCIe splitter onboard an are usually 10-20times more expensive (but they do not need any support of the MoBo)

 

Beside of the price there is no real difference or downside. Only if the "raid" card offers more ports than the host has lanes to offer, the onboard switch will slow down things a bit if those cards are used in parallel (it would be not a good idea to put both nvme of a mirrored pool onto the same card)

 

[hunter69]

On 4/6/2023 at 11:31 PM, MAM59 said:

No, it means that the existing 8x slot (ususally the 2nd one?) can either be used as 1*8x or can be switched to 2*4x.

So you could either use a cheap 1port adaptor (they only use 4 lanes then) or a cheap 2port adapter (or more, but only 2 devices will be available then).

 

With "cheap" I mean those cards without any electronics. These are usually 10-20€ each.

 

The "raid" cards that you have read of have an own PCIe splitter onboard an are usually 10-20times more expensive (but they do not need any support of the MoBo)

 

Beside of the price there is no real difference or downside. Only if the "raid" card offers more ports than the host has lanes to offer, the onboard switch will slow down things a bit if those cards are used in parallel (it would be not a good idea to put both nvme of a mirrored pool onto the same card)

 

Thanks for the clarification