Score:0

Can I make hotremove/add on raid5 with mdadm?

wf flag

I created and assembled software RAID5 array (mdadm), 15 SSD disks. If I physically remove several disks and add them back, RAID doesn't assembles back. Disks stays in "spare" mode. Even after reassembling by commands.

But if I manually fail a drives: mdadm /dev/md0 --fail /dev/sd[xyz] and then after mdadm /dev/md0 --remove /dev/sd[xyz] remove physically and add disks back, with command mdadm /dev/md0 --add /dev/sd[xyz] RAID works fine!

Can anybody guess me, if there is a hot swap\remove\add in soft-raid mdadm or not? Should I always use commands before removing disks? No automation?

br flag
Please don't use R5, most storage professionals have considered it wildly dangerous for over a decade and we can't believe it's still an option on disk controllers and in OS's - we deal with people all the time who come here asking for help getting their data back from a broken R5. Please only use R1/10, R6/60 or ZRAID if you like that kind of thing - R5 has been 'dead' for a long time.
Mike Andrews avatar
ng flag
RAID 5 can only tolerate the loss of a single drive. If you lose two drives, the array is inoperative until you can bring the second failed drive back. This is a limitation of RAID 5 generally, not something specific to Linux.
I sit in a Tesla and translated this thread with Ai:

mangohost

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.