Intel RAID Expander Card RES2SV240 (powered via external Molex)
My goal:
I need to place my hard drives more than 1 meter away. Long SATA cables aren’t recommended, so I’m trying to use the Intel RES2SV240 expander card to solve this.
What I’ve tried:
With a single SAS-to-SAS cable from the HBA to the expander and one SAS-to-SATA breakout cable to 4 disks, the system will boot, but it takes a long time and shows a flood of errors during POST (too fast to capture). The setup feels unstable.
When I tried adding a second SAS-to-SAS cable for dual-link, hoping to add more disks, things got worse. Disks started showing up twice and TrueNAS didn’t handle it well.
I tested adding hw.mps.dual_function=1 in loader.conf, but that didn’t help.
Problem:
Right now, I can’t get the expander working in a stable way. Even the “semi-working” setup with one link feels flaky. I suspect I may be missing something in either configuration or cabling.
Question:
Does anyone have experience getting the RES2SV240 working reliably with TrueNAS and LSI 9211 HBAs?
Is dual-link even supported with this card on FreeBSD/TrueNAS?
Any documentation or known working setups would be a huge help.
Thanks
That doesn’t appear to be a valid configuration. The manual only shows a single cable being used as input (from the main board SAS).
I am not sure what the cause of your issues is, it could be a bad expander card, bad cables or, since you specficially mention it, cabling that is too long. How long are we talking here (from the HBA to the expanders and from the expander to the drives), and what made you think an expander was the solution?
The run from the HBA in my motherboard to the expander is about 1 meter, and from the expander to the drives is another ~50 cm.
I didn’t even know cards like this existed until recently — I was originally running with 2-meter SATA cables, which I knew wasn’t ideal. When I found out about expanders, I figured it would be a cleaner and more reliable solution, so I picked up this Intel RES2SV240. The unit I got was actually brand new.
My main goal here is to improve on both stability and performance compared to the long SATA cable setup.
The tricky part is with dual-link: I don’t know how to capture the boot errors, but they fly by on screen, and later when looking at logs it looked like the disks were showing up twice. I thought maybe it was a setting I missed, or that I’d used the wrong ports for the dual-link connection but from what I can tell, all ports on this expander can act as “IN” so the cabling itself should be fine.
To answer the cable length question: my “case” is actually a breaker closet with a custom layout and brackets. Drives are stacked vertically like a skyscraper with custom power cabling, and airflow/cooling is handled well. This has been running for years.
Previously I had no choice but to use 2m SATA cables to reach everything. I know that’s out of spec, and that’s exactly why I picked up the expander , I was hoping it would let me ditch those long SATA runs and give a more stable, supported setup.
So now the run is ~1m from the HBA to the expander, and another ~50cm out to the disks. Do you think that’s a reasonable single-path setup, or would you recommend another approach for reliability at this distance?
That should be within spec, since the HBA to expander is using SAS and thus the higher signaling voltage - however, if the last 0.5m is just in open-air there might be more potential for interference vs. inside a case. eSATA is rated for longer distances but is more shielded IIRC.
You’ll definitely need to stick with a single path though, regardless of whether or not your disks themselves are SAS or SATA.
Given the price of these cards (second hand) - is it worth trying a different expander.
I did well with an Adaptec SAS expander although I have since decomm’d the “home made” JBOD (PC Case, Adaptec SAS Expander, PSU with a fake motherboard plug and 12 HDD’s in a set of hot swap bays)
