3GB/s or 6GB/s on Motherboard?

Hello folks,

Newbie builder here--I've tried to search this answer, but didn't find a specific answer.  My confusion (and the confusion exists at many levels) is in regards to what SATA throughput speed is needed/best/compatible on the Motherboard as well as within PCIe expansion controller cards.  The SuperMicro card (AOC-SASLP-MV8) is spec'd at 3GB/s throughput.  So here are my Q's:

1. Do you have to have the same throughput spec on the Motherboard SATA ports as on the SAS RAID Controller?

2. Can you mix and match speeds?

3. Does it involve more setup/build/bios editing time if you do mix?

4. Will a 6GB/s perform the initial setup/disk clearing faster?

5. Should I look for 6GB/s expansion cards?  Do they exist?

I have been looking at Motherboards that have 8 6GB/s SATA ports, but want to make sure that I can add additional drives later.  And I want to make sure it will work as I grow and minimize the setup/bios editing later.  My goal is to create a server that can hold 15 3TB or 4TB disks.

Thanks in advance.

Hello folks,

 

Newbie builder here--I've tried to search this answer, but didn't find a specific answer.  My confusion (and the confusion exists at many levels) is in regards to what SATA throughput speed is needed/best/compatible on the Motherboard as well as within PCIe expansion controller cards.  The SuperMicro card (AOC-SASLP-MV8) is spec'd at 3GB/s throughput.  So here are my Q's:

Welcome to unRAID then 

1. Do you have to have the same throughput spec on the Motherboard SATA ports as on the SAS RAID Controller?

No.

2. Can you mix and match speeds?

Technically yes...controllers and drives should be up- and downwards compatible and negotiate speeds accordingly.

For myself it is unheard of that at least the "next neighbour" is not supported.

Meaning you can team SATA150 and SATA300, as well as team SATA300 and SAT600....not sure what a SATA600 disk will do with a SATA150 card or vice versa.

3. Does it involve more setup/build/bios editing time if you do mix?

No, speed negotiation should be perfomed silently between parts

4. Will a 6GB/s perform the initial setup/disk clearing faster?

No...the process is based on a single disk and this will not even saturate SAT150 if it is a mechanical drive.

unRAID by design does not use striping, so single disk speed is what you will get from your array for a file...since only one NIC is suported,

traffic in/out of the unRAID box will max out at that NIC speed in total.

5. Should I look for 6GB/s expansion cards?  Do they exist?

Yes, they do exist.....look for a LSI 2008 card or higher. The IBM ServeRAID M1015 is very popular since it is available for little money and can be converted into a HBA.

Using such a card makes sense if you want to employ more disks with combination of an expander. This will allow to provide a better baseline, since all disks share the bandwith of the HBA driving the array.

I have been looking at Motherboards that have 8 6GB/s SATA ports, but want to make sure that I can add additional drives later.  And I want to make sure it will work as I grow and minimize the setup/bios editing later.  My goal is to create a server that can hold 15 3TB or 4TB disks.

see above, 6GB makes sense only for driving more drives via a HBA plus expander...or when you plan to use SDDs as base for your array 

Thank You Ford Prefect!!!

I think for what I want (simple SMB/file shares) for pictures, backups, etc. the lower level Supermicro card will suffice.  With my goal of ~15 drives, I think I can get them all connected with the motherboard and one card (which says it can drive 8 drives).  Please let me know if there's some inherent limitation to that plan...I understand that the NIC and/or my network may be the limiting factor...

My main concern was committing to the purchase of the gear only to find out I can't mix throughput speeds, and you've allayed that fear.

Thanks again!  Very helpful...

...no worries.

Just make sure that the SATA chipset of your mobo is supported.

Most likely, when having 8 ports, the mobo will employ two different chipsets having 6 native ports plus two additional from another chip, like ASMedia or Marvel.