Post #2126760

2026-05-07 03:11 UTC

The main issue is statefullness of the host. Say you’re on a laptop, and you get an external JBOD box without any hosted controller. You use that laptop to setup a RAID1 array on 2 disks, and go about your business. Few weeks in you’re in the middle of some editing of video or whatever, and you have a power outage. That RAID array is assuredly damaged or dead. Your host machine being the controller in the middle of a write when the entire array dissapears is going to give up quickly, and the cached data in flux to write is gone. You miiight be able to recover the array if you’re lucky, but whatever you’re working on is gone. A number of diff5scenariis where this may happen exist without a power outage, but the problem is the target not being able to manage its own interrupt, and you have two different states in two different devices that won’t match. It’s toast.

Replies (1)

@Lemmchen@feddit.org 2026-05-07 10:16

You miiight be able to recover the array if you’re lucky I don’t see how this would apply. Having the disks connected externally is the same as having them connected internally, maybe over a different bus/protocol, but the principle is the same. No RAID solution I know of would lose the array on a power outage (AFAIK). the problem is the target not being able to manage its own interrupt Honestly I don’t see how interrupt handling would be any different between internally or externally connected devives, except for different buses/protocols handling it differently intrinsicly. Are you absolutely sure this is a thing or are you just speculating? you have two different states Maybe I’m too spolied by using ZFS, but again I don’t think this would actually be a problem. But AFAICT you don’t even need a CoW filesystem for that to be not a problem. Every journaling filesystem (e.g. ext4) would solve this by dismissing the newest non-consistent data and restore a working state. I mean, there are 60-bay 19" expansion units for enterprise storage systems. I doubt these would be a thing if having the drives connected externally was a problem.

Open ##2148816