I have a backplane that is SAS/SATA for drives and on the back it uses sata to connect to HBA card.
My question is if I use SAS3 drives and use the sata to SAS3 HBA PCI-e card will it work and will I get the full bandwidth 12Gbps?
Don’t quite understand the ask.
SAS drives require a SAS specific backplane. SATA drives work on SAS or SATA backplanes.
If the backplane is SAS/SATA then it connects as SAS unless it is some off the wall contraption which would be asking for trouble.
SAS drives can be either 6GB/s (SAS/2) or 12GB/s (SAS/3) depending upon drive model and on the SAS controller capability.
Truenas does not support dual port connections to SAS drives if you are thinking along those lines.
my experience with an icydock is that it will work - you’ll only get a single channel to the sas drive though. The fact that it’s a sata plug in the middle doesn’t detract from the fact that it will sort its own protocol with the HBA. It’s a cheap method for manufacturers to make ‘dual’ capable backplanes for what it most like a 99% sales to home users with sata boards only.
These things are dumb backplanes in that they only match traces from drive to socket. If the cables etc are good enough, you should get the full 12gb/s rate. If not, you might find it downrates until it works or it may just fail completely.
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Thanks for the reply. My backplane on the front it is SAS/SATA connector. On the back of the backplane it is SATA connectors.
I appreciate the time and patience. So for my own clarification the backplane does not hamper the connection as long as the path from the DRIVE to the HBA PCI-e card is good doesn’t matter if use SATA cables?
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To answer that question again more directly. If you connect the board to a SAS HBA in IT mode and if the connection is SAS3 from the SAS3 drive all the way through all the hardware then yes you could get the 12Gb/s speed. If any part of the path or hardware is not SAS3 then you will get SAS2 speeds which is 6GB/s. Any SATA drives will run at SATA speeds even if the hardware is SAS3 (12Gb/s) capable.
If it is a dumb board with all the connector slots on one side routed to a SATA connector and all the connector slots on the other side routed to a SAS connector, then it may be essentially what amounts to a breakout board and might work at 12GB/s on the SAS side. SATA side will be SATA speeds only.
For othe other part of the question.
In general a true SATA HBA card cannot see SAS drives and SAS drives are incompatible with SATA only hardware.
A HBA in IT mode that is not SATA only is designed to see both SAS and SATA drives. These are the common LSI cards and variants posted on the forums as compatible with Truenas. This is because SAS controllers and HBAs are built to be backward-compatible with SATA, while SATA only controllers lack the necessary signaling to communicate with SAS drives.
So SAS cannot use SATA hardware as it is not compatible with SATA or a SATA only connector which are also not compatible with SAS drives (a SAS drive’s connector lacks the gap that a SATA connector has). SATA can use SAS because SATA is a subset of SAS and the SATA drives are compatible with SAS connectors and the SAS hardware is designed to communicate with the SATA drives.
I really appreciate your time and it clarifies my questions. So my only concern is the HBA card supporting SAS3 and not the SATA cables. I cannot post photos here as that would have been clearer. I again appreciate your time and patience and thanks so much for the information.
If you post brand and model of the card maybe some will look it up or already know about the card.
I think you need to complete the disco bots forum walk through to be able to post photos. There should be a welcome notification. It would be under the bell (notifications) on your forum account
Cables are cables. If you connect a SAS HBA to a passive backplane with breakout cables to SATA, it should work as SAS or SATA, depending on the drive at the end.
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