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PSU not detected after upgrade to FW 6.9.1
After upgrading to FW version 6.9.1 from 6.8.x i see log messages that indicate PSU1 not detected and PSU2 not detected. The unit is populated with 12 4TB drives. I've attempted to upload the logs ...
This past weekend I was able to shut down the unit, remove the power cords, remove the power supplies, release the drives from each slot and blow out any dust (there was no visible dust inside the unit and while compressed air was blowing there was no visible dust being displaced) and clean any dirt from the contacts on the back of the power supplies (there was no visible difference after cleaning the contacts.
The unit was reassembled and powered up. Since 6.9.2 had been downloaded it was installed as the machine rebooted.
Upon accessing the GUI the power supplies were both shown as installed and functioning.
While the problem is solved I'm not 100% sure that dirt was the problem and the reappearance of the power supplies could be associated with the extended amount of time the unit was powered down.
I debugged one RMA RN3220 with this problem. It turned out that the problem might be related to pollutant in the air :(
See attached picture, the black dust has weak conductivity, resulted I2C bus voltage drop on backplane. While it does not affect backplane I2C bus operation, it does affect I2C bus buffer for PSU PMBus which is sensitive to voltage level. I cleaned up backplane using dust blower, the system was back to normal.
If PSU is not detected right after boot up. Would appreciate if you can try this and report back:
1. Gracefully shutdown NAS
2. Take out all hard drives(keep it in order and put back in same order later even though this is not needed)
3. Visual inspect if there is excessive dust on backplane. Use compressed air can to clean up backplane, especially the area with components. You can also get access of back of backplane by removing top cover if clean from front does not recover the PSU monitoring
4. Replace drive(and cover)
5. Check if PSU is found, chance is it will.
While your suggestion is excellent in this case it is probably not the case. The units operate in a temperature controlled clean environment. While it is not as clean as a true clean room the air is still very clean. So clean that units operating a year or more will have no visible dust on the fan grills or inside. In addition this issue began on the reboot immediately following the update to 6.9.1 from 6.8.x so it is likely related to that change rather than an hardware issue.
Since this unit is a storage domain for a virtual server environment I will have to wait until the maintenance window is available to take it offline and open the cover to clean the backplane (both on the drive side and on the back side) as well as the PSU connection points.
There is a serial console port on back of RN4220/RN3220. The settings are 115200-8N1.
BIOS posts two types of message during POST(Power On Self Test) regarding PSU:
PSU x is not present (This indicates that PSU is not detected)
PSU x is not electrified (Normal message)
If BIOS manages to detect PSU but firmware fails, then we know for sure it is caused by firmware update.
We did review I2C driver code history, it does not have any change for long time because the PMBus is driven by mature Nuvoton super IO chip.
If the server is running in server room, I agree that chance of pollutant/moisture causing problem is extremely low. We have many RN4220/RN3220 running in not so well controlled labs, none of these systems has this issue. We did many versions of firmware update/downgrade and these were OK.
I don't have other easy no-risk ways for you to troubleshoot this problem. If you are comfortable with messing with drives and screws(several dozens of these!), I can send you a good drive cage with backplane, then you can swap out yours to see if problem goes away. The reason that I suspect the backplane is that only backplane shares I2C bus with PSU. All other I2C devices are on a different I2C bus.
I'll check it out this weekend during the scheduled maintenance window and see what the results are.
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