ReadyNAS intermittently fails to boot or shows error on screen

Question

Hi all, I am having a problem with my aging ReadyNAS Ultra 4. Some time ago I upgraded to ReadyOS 6.x (I know this isn't officially supported) and it worked fine but probably 2 years later I am finding the NAS inaccessible at times and a message is displayed on the LCD. Today the message was:
swiotlb_unmap_sg_attrs+28
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If I force it off then on it will usually boot up fine and the shares will be accessible. Does anyone have any ideas where I can start trying to find the cause of this? I recently updated to the latest version but this has been going on intermittently for some time now.
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Thanks

Retired_Member · Answer

Hi AK47-UK, at certain peaks the poor granny might run out of memory and what you see is the result. I would deinstall all apps and also disable all services you do not truely need.
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Then let it run and see, whether there are any hickups again. If not, bring back those apps and services you deinstalled/disabled one by one and see where you will hit the limits. Of course you will need some patience and time for this approach. Lets see, whether anybody else has other recommendations to tackle this.
Good luck with fixing and kind regards

Retired_Member · Answer

Lets assume, you only want to support file services for windows clients, you could safely disable AFP (dedicated to mac clients) and NFS (for linux workstations).
Do NOT disable HTTP and HTTPS or you might not be able to access the admin page through your browser.
Keeping UPnP and SSH enabled depends a bit on what else you expect your Nas to support.
Conceptually, UPnP extends plug and play (a technology for dynamically attaching devices directly to a computer) to zero configuration networking for residential and soho wireless networks. UPnP devices are "plug and play" in that, when connected to a network, they automatically establish working configurations with other devices. (more here https://en.wikipedia.org/wiki/Universal_Plug_and_Play). If you don't need this support, disable it. Keeping it disable is also more secure :-)
SSH's most visible application is for access to shell accounts on unix-like operating systems (more here https://en.wikipedia.org/wiki/Secure_Shell), as used by your nas. So, if you don't want to poke around in the intestines of your nas using line mode, disable this, too.
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StephenB · Answer

4 GB should be enough, so I am not convinced it is a memory issue. But you&nbsp;can disable uPNP, though I don't think it takes any significant resourses.&nbsp; File Search can use quite a bit, so if you can live without it you could disable it.
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FWIW, swiotlb_unmap_sg_attrs is a function used in DMA transfers.
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Other steps

try running a RAID scrub from volume settings wheel, and when it completes examine the SMART stats on the disk.
maybe try using the boot menu to run a memory test.
Check the OS partition fullness (not likely to be a problem in your case, but not hard to check).

If you have ssh enabled, you could try copying the data volume (and perhaps the OS partition) to /dev/null as a test.
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AK47-UK · Answer

Thanks all, it is used as a universal backup target and file repo (not used often but still occasionally) so I like to have AFP/NFS as I run macOS/Linux VMs on my other server and like to have SSH enabled in case it's ever needed! But I shall disable UPnP and File Search to see if that helps.
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I think it has happened again today, my NAS is not accessible remotely so will wait til I get back to check the status on the screen. Based on what you have said I am wondering if the RAM module may have developed a fault so I will see if I can get a KGM to replace it with and also try the memory scan. I will also try the other steps mentioned by Stephen.
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Thanks again for all of your help

bedlam1 · Answer

.....or upgrade the memory anyway

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ReadyNAS intermittently fails to boot or shows error on screen

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