From a2813e0490698f96c97fab881c1aa479c2f43d3d Mon Sep 17 00:00:00 2001 From: Malin Freeborn Date: Fri, 14 Jan 2022 12:32:40 +0100 Subject: [PATCH] add mdadm --- data/mdadm.md | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 data/mdadm.md diff --git a/data/mdadm.md b/data/mdadm.md new file mode 100644 index 0000000..6362db3 --- /dev/null +++ b/data/mdadm.md @@ -0,0 +1,40 @@ +# RAID5 + +You will need 4 disks and the `mdadm` package. +The total size will be equal to the disks x 3, because one will be used for redundancy. + +> sudo mdadm --create --verbose /dev/*md127* --level=5 --raid-devices=*4* */dev/sdb /dev/sdc /dev/sdd /dev/sde* + +Note the variable parts: + +- The name of the device could be `/dev/md12` or whatever +- The number of devices could be larger, but must be at least 4 for raid 5 +- We end by listing all devices in the new `md` device. + +Now look at how the raid status: + +> cat /proc/mdstat + +This will increase until the entire thing is fine. + +Check the health of your `mdadm` array: + +> sudo mdadm --detail /dev/md127 + +You should see `State : clean`. If you see it is `degraded`, then a disk has broken. + +## Replacing a Disk + +First, prepare the disk with both a gpt partition table, and a partition: + +> sudo parted --script /dev/sdb mklabel gpt mkpart primary 1MiB -2048s + +Add the appropriate file system to it, e.g.: + +> sudo mkfs.ext4 /dev/sdb1 + +Then finally, add the disk: + +> sudo mdadm --add /dev/md127 /dev/sdb1 + +