On 26/11/17 17:29, Duane wrote: > You're right I failed and removed device 3, then failed and removed > device 2, which broke my array. > > Let's assume I haven't messed things up any more than I already have. > > Is there a method to reverse the above operations for device 2 and > device 3? > > Thanks, Duane > My raid-fu is mostly theoretical, but what I would try is as follows. It's assembled the broken array as md0, so mdadm /dev/md0 --re-add /dev/device2 followed by mdadm /dev/md0 --re-add /dev/device3 That won't cause any further damage, and may work fine. Beyond that, I wouldn't like to suggest anything - if it doesn't work you'll probably need to use things like --force, which could easily break stuff. But re-add will probably work. And my syntax might not work - you might need to specify the mode like --grow or --manage, I don't know. Suck it and see, at least this won't do any damage, and if it doesn't work we'll have to wait for further advice. Cheers, Wol > > > On 2017-11-26 05:04 AM, Wols Lists wrote: >> On 26/11/17 01:50, Duane wrote: >>> I have 3 RAID5 devices. When I assemble them, I end up with a RAID0 >>> device. >>> >>> What is the cause? What is the solution? >>> >>> All I can think of is the fact that there is only 1 active device. I had >>> 2 but then manually failed it. I want to reassemble a RAID5 array and >>> then re-add the second device. >>> >> OUCH! >> >> Sorry. You have a 3-device raid-5. You only have 1 working device. Your >> array is well broken. >> >> You can't "reassemble raid5 then readd the second device". You need to >> readd the second device in order to get your raid5 back. I'll let >> someone else tell you how, but you need a MINIMUM of two devices to get >> your raid working again. Then you need to get your third device added >> back otherwise your raid 5 is broken. >> >> DON'T DO ANYTHING WITHOUT ADVICE. I'm sorry, but your message says you >> don't understand how raid works, and you are on the verge of destroying >> your array irrevocably. It should be a simple recovery, *provided* you >> don't make any mistakes. >> >> Cheers, >> Wol -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
