Old LS421 freezing, no errors reported

[oliverb]

Looking for advice, the NAS in question is well out of warranty.

Anyway... The LS421 was suppled as an enclosure, I fitted WD 1T "RED" drives configured as "mirrors" and it has been running with the same drives ever since.

Recently I've discovered that the LS had become unresponsive. On cycling the power everything appears normal and on inspection I discovered a considerable amount of dust which I've done my best to brush/blow out. I also put the latest firmware on.
Disk check reports no errors, The LS just appears to go "down" after a few days, with no indication of what is wrong.

My inclination is to suspect a drive problem such as one drive simply "freezing" and ceasing to respond altogether.

[1000001101000]

Failing drives is always the first thing to consider. It's a little odd that the device would freeze rather than show as degraded if only one drive was failing.

I assume the first thing you did was make sure you have backups of any data on the device, if not do that first.

In addition to checking the health of those drives, I would check to make sure the fan is working and if possible check the output of the power supply. What you describe could be explained by overheating or power supply problems.

[oliverb]

Regarding backups the good news is this is the backup destination for another device elsewhere, not the primary, and I also have copies on removable drives.

Regarding the hard drives I know a failure should return an error and "degrade", but if I understand correctly the box's firmware runs off of the drive too, so could the wrong kind of failure just bring it to a sudden stop?

The fan is turning. I measured 12v from the power supply, but that was off-load as I don't have a splitter cable to measure it while it is powering the NAS. I do wonder about the power supply though, it has been in service nearly a decade and power supplies do seem to wear out.

Update: It has frozen up again a couple of times, both times it required cycling the power to restart it, it wouldn't react to the switch on the back.

[oliverb]

The NAS is still just quietly going offline. Still no clues but I don't really know what tests I could run so yeah I haven't tried much apart from setting a startup and shutdown schedule to see if it would restart out of a crash (no) and switching the drives round.

Maybe I'll have another go at cleaning it out, but I think I did a good job of clearing it out last time.

I don't think it is the drives but I could find some other drive to put in just to rule that out.

The power supply checked out OK off load, but that's what you'd expect. Maybe I can get a splitter adaptor so I can measure it under load.