I have a few RAID 5 disks from a computer that broke and I’m wondering, I have them all plugged in but how do I reformat them for normal use? My Linux machine doesn’t even pick up the devices. Just a few gigs of TMPFS.

  • How do you know your computer doesn't pick them up? You shouldn't expect the Raid5 to automagically assemble on your system, it doesn't work like that. They will likely show up as raid members, but won't be readable at all. – djsmiley2k Jul 17 '17 at 19:15
  • @djsmiley2k The question reads “…do I reformat them for normal use?” Which to me means just reformatting the disks for stand-alone use like any normal hard drive. That is a fairly simple thing to do… If that is indeed what this question is about? If so it’s simply odd that the disks are not being picked up by the OS. – JakeGould Jul 17 '17 at 19:18
  • How did you determine it doesn’t see the devices? Please provide the output of fdisk -l. – Daniel B Jul 17 '17 at 19:23
  • As @Tonny said, the key is that it needs more than just formatting, it needs re-partitioning. In a raid 5 the partition table would also have been spread across all three disks... thus Linux can't identify the partitions. This would cause, for example, /dev/sdb to appear, but not /dev/sdb1 and /dev/sdb2, etc. One can also use blkid as root to see what block devices are detected, if it doesn't show up there you have more serious problems. – Cliff Armstrong Jul 17 '17 at 20:00

The disks should show as devices in your system but they most likely don't have any valid partition table on it.

This makes them unavailable for automatically mounting/showing them on your desktop.

Use fdisk, cfdisk, gparted or any other partitioning tool of your choice.

It should show the disks as either raid-member or as unformatted.

Simply give it a fresh partition table (either MBR or GPT, depending on your system and BIOS, when in doubt use the same type as the disk your /-filesystem is on) and then you can proceed as usual creating partitions.

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