What happens when you plug SAS 2 Drives into a SAS 3 Controller?

[Cookiefamily]

Hello,

I recently got gifted some servers (Fujitsu RX300 S8), but they came without HDDs and a Raid Controller based on the SAS2208. Since I havent been successfull in crossflashing it to a 2308, I wanted to also buy some used HBAs for them.

The drives I want to use are all SAS2 (6Gbit/s). Would I have any benefit of going with a SAS 3 (12Gbit/s) Controller since 16 drives can definitly saturate a SAS 2 link or will it downgrade everything to SAS 2 as soon as you have a SAS 2 drive on your backplane?

 

[HarambeLives]

Is there an expander in there? If there is a SAS2 expander, you will get zero benefit going to a SAS3 HBA

That being said, SAS3 HBA's are not THAT expensive, and they are more power efficient than the SAS2 models, and they will be supported for longer just on the fact they are newer. For that reason, I went with a SAS3 HBA. After years of buying equipment, I've come to learn that you should buy the best hardware you can

I am unsure if a SAS3 expander will link to the HBA at SAS3 speeds with all SAS2 drives. I would ASSUME the expander would link up at 12G, and then you'd have extra bandwidth back down to the controller

 

[Johnnie Black]

I am unsure if a SAS3 expander will link to the HBA at SAS3 speeds with all SAS2 drives.

LSI SAS3 expanders have Databolt that can get you close to SAS3 performance with SAS2/SATA3 devices, some PMC expanders also have a similar feature, e.g., the one used in the Intel RES3TV360.

 

[Cookiefamily]

I guess there are SAS Expanders in there as it is an 8 Port RAID Controller wtih 16 Drive Bays.

Thank you for your answers, gonna take a look where I can get a couple of good deals on used LSI HBAs then :)