[Milhouse]

One of my Pis boots from a 128 MB SD card that is at least 10 years old. Storage is on USB. I don't see what benefit there is to a bigger or faster card if it is only read during boot up and only written to during an update, or if you edit the config or command files.

Same here.

I also don't see how corruption of the system partition could even be an issue. How is it going to be corrupted if is never being written to in everyday use?

Obviously, not all Pi's are prone to corruption, but for those that are...

If your only SD card partition is the primary boot partition, your only chance of corruption is while updating, or when modifying configuration files, as these are the only times the partition should be written to. Although it's unusual for the FAT partition itself to be corrupted, it's not unusual to see corrupt files written that render the device unbootable until the corrupt files are overwritten with working versions.

However if you have both primary and /storage partitions on the SD card, it's quite likely that the /storage partition will be corrupted as it is first mounted, hence moving the /storage partition to NFS, SMB or USB to significantly reduce the risk of complete system failure due to corruption. Even cleanly unmounted /storage partitions have been corrupted when next mounted.

I once wrote a method for detecting during OpenELEC boot when the SD card wasn't correctly initialised, it involved timing how long it would take to write a 1MB file to the FAT partition - it should normally take <1 second but there were times when it would take 10-15 seconds. I would have the Pi reboot itself when these abnormal IO times were detected and it eliminated corruption of both firmware (during any subsequent update) and of the secondary /storage partition whenever it was mounted. Not a nice solution by any means, but it worked pretty reliably. I've since given away that Pi which suffered from corruption, and my current Pi doesn't have any SD corruption problems...