After... not sure how long, but it was pre-LEDE, I'm trying to return to OpenWRT. I've ordered a new router that supports it (the Dynalink WRX36), and while the setup is a little complicated, I can follow instructions. (The only deviation is the guide said "double check all you have latest versions in case this doc page was not updated," so I've downloaded the 23.05.2 version of all 3 files rather than using the linked ones in the TOH page, which is hopefully correct since it asked me to do that?)
I'm a little confused by what the commands actually do though, and I'm curious about the note at the bottom of the page, "The Dynalink/Askey OEM firmware has Dual-image support for firmware upgrade fail-safe. This feature is not yet fully supported by OpenWrt for this device."
I would assume that not supporting dual-image means that it won't toggle between images on firmware upgrade, so I don't actually have a backup image if I break something? I'm also guessing that this'll put all the wear in one region?
Can/should I manually switch the partitions? How?
What do I do if I build & upload a subtly corrupt image or if a flash fails for some reason? I think that's why there are optional instructions to tell it to preferentially boot off ramdisk on USB, but how do I restore a good image from there? Is that repeating ubiformat from the install guide or a sysupgrade?
Does the reset button still reset a bad config or is that only for NOR devices?
(I've never had a NAND device before, so how much do I need to worry about block errors and are there any differences in behavior/usage/upgrading?)
You can configure a USB based recovery, but that's something you need to set up yourself (changing the boot commands).
Additionally there's serial based console access, 2mm pitch, but relatively easy to dismantle the case and access the populated serial header.
That should work.
You won't kill the NAND by upgrading OpenWrt 'often' (let's define 'often' as once or twice a week on average, for 5++ years), but you should avoid excessive logging (OpenWrt doesn't do this by default anyways) or similar continuous usage on NAND (not much different to NOR, though). NAND is a bit more fragile than NOR (and harder to flash externally/ replace, etc.), but for 'normal' usage it will do (and gives you more space in return).
That endurance number you gave - that works out to ~250 writes on the low end. Is that accurate? Or was that an accidental underestimate? I'd read that a decent NAND should get at least 500 or so, but perhaps this is a different type.
A stray thought just occurred to me... is it possible to offload the entire image (kernel, FS, R/W partition, etc) to a USB drive if it can boot off and (presumably the kernel can then) write to USB?
I still had some questions, too:
How do I reinstall a non-broken image via the ramdisk USB boot if something goes wrong? That wasn't specifically explained out in the install guide and I'm not sure if If I'd need one ubiformat command, both, or additional commands to do so.
I wasn't calculating the number of writes at all, just mentioning that you won't kill it by 'hyperactive, but normal' usage, even if you reflash it for breakfast, noon and dinner.