I’m looking to expand the storage on my TX2 dev board (R32 4.4). I use the built in SATA port w/ an SSD but I want to add a PCIe card w/ a SATA controller + >= 2x SATA ports. My new SSDs will only require 5V for power, so I’m thinking of using each of the J21 5V pins (+ separate GNDs) for each SSD (each 5V pin allows up to 1A and the SSDs are each <5W at full load).
The trickier part seems to be compatibility of the PCIe card w/ the TX2. It seems like:
- ASM1062 (also ASM1061?) controller based cards may require kernel patching due to being PCIe 2.0 (Gen2) and only supporting 32-bit MSI or possibly have other issues. I haven’t done a kernel patch before but don’t mind learning if needed.
This user has a card w/ a Marvell 88SE9215 (also Gen2) that seems to detect but not mount their disk possibly due to ASPM (it’s not clear to me the user confirmed resolving their issue and that it actually was ASPM?). Other controllers I’ve seen for cards in my price range use Marvell 88SE9235 (Gen2) whose datasheet only indicates “MSI compatibility”.
As I understand it, PCIe 3.0 (Gen3) introduced MSI-X which mandates 64-bit MSI support. So my best bet seems to be a Gen3 card (even though the TX2 is Gen2) with 2 ports such as this? This uses a Gen3 Jmicron JMB582 controller.
- Does anyone know of actual working examples of reasonably priced PCIe expansion cards (or controller chips) w/ (only) SATA ports and w/ multiple disks?
- Does my reasoning for preferring a Gen3 card make sense? Since I’ve seen examples of both the ASM and Marvell based cards having issues on these forums this seems another pro in this direction.
- Does the power “breakout” I described make sense (one SSD per 5V pin)?
Most of this I cannot answer, but:
- If you use a model of Jetson only rated to a PCIe revision of 2, then there is no chance of a PCIe v3 card actually working at that speed (it would throttle back to rev. 2 or rev. 1).
- It is unlikely the power of the Jetson will be sufficient for everything. You would very likely need an external power for the SSDs.
Thanks for your input!
Yes, I’m aware of the Gen2 limitation of any Gen3 cards on the TX2. It’s not an issue for me and I’m much more concerned regarding compatibility and just being able to read/mount the actual disks. I’ve seen references in some threads to “internal testing” by the jetson/nvidia staff of certain PCIe cards for compatibility. Is there anyone I could reach out to (by PM on this forum for example) for checking what/if they’ve tested as far as SATA cards?
That’s an interesting point regarding power. According to the reply/solution for this post there should be no problem using all 3x 5V pins (I only need 2) to each draw up to 1A as the 5V DC-DC (TPS53015) can output up to 7A on the VDD_5V0_IO_SYS rail (in addition to the 4A max for the VDD_IN rail going to the Jetson). Am I missing something?
I don’t know of anyone who specifically tests hardware, so I can’t answer that.
So far as power goes it isn’t just a case of providing a certain amount of raw current. The issue is that the regulation must be extremely good to prevent rebooting, and required current for an SSD is not steady…it can go up or down depending on what is going on, and it can do so suddenly. This would mean a single power supply current source would have increased regulation quality requirements. Having separate supplies to isolate the two reduces regulation quality requirements. Technically you could power them all as you mention, but I suspect it would have real world issues with regulation quality causing reboot.
OK thanks yes that part is clear and I understand also that the line regulation on the TPS53015 is worst at low output currents up to ~1A (only the SSDs would draw any real load from VDD_5V0_IO_SYS). I don’t know whether the ~12mV variation from the datasheet (among other potential issues) is too much for the controller on the SSD. Anyways I will keep looking to see if I can find a suitable expansion card.
This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.