Differences

This shows you the differences between two versions of the page.

--- raid [2011/03/04 00:55] – external edit 127.0.0.1
+++ raid [2022/01/31 21:11] (current) – [Rebuild array with replaced disk] paulsmith
@@ Line 1: / Line 1: @@
+====== RAID ======
+===== Create new RAID =====
+==== dev nodes: ====
+<code>
+If you built raid into the kernel as modules
+modprobe raid5
+Create some nodes
+mknod /dev/md0 b 9 0
+mknod /dev/md1 b 9 1
+mknod /dev/md2 b 9 2
+</code>
+==== create: ====
+<code>
+RAID0
+mdadm --create --level=0 --chunk=4 --raid-devices=2 /dev/md0 /dev/hde2 /dev/hdg2
+mdadm --create --level=0 --chunk=4 --raid-devices=2 /dev/md1 /dev/hde3 /dev/hdg3
+RAID1
+mdadm --create --level=1 --chunk=32 --raid-devices=2 /dev/md0 /dev/sda3 /dev/sdb3
+RAID5
+mdadm --create --level=5 --chunk=32 --raid-devices=3 /dev/md0 /dev/sdc2 /dev/sdd2 /dev/sde2
+mdadm --create --level=5 --chunk=64 --raid-devices=3 /dev/md1 /dev/sdc3 /dev/sdd3 /dev/sde3
+Stop a raid build: mdadm -S /dev/md1
+Watch the raid being built: watch -n 10 cat /proc/mdstat
+</code>
+===== Reassemble RAID =====
+  mdadm --assemble /dev/md0 /dev/sda3 /dev/sdb3
+===== Take a disk offline =====
+<code>
+</code>
+===== Build a raid from scratch =====
+<code>
+modprobe raid5
+#  mknod /dev/md0 b 9 0   <- not sure needed now, mdadm might create it
+fdisk /dev/sdb   g enter, n enter 1 enter enter enter, t raid, w enter
+fdisk /dev/sdc   g enter, n enter 1 enter enter enter, t raid, w enter
+fdisk /dev/sdd   g enter, n enter 1 enter enter enter, t raid, w enter
+mdadm --create --level=5 --chunk=64 --raid-devices=4 /dev/md0 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1
+</code>
+===== Rebuild array with replaced disk =====
+<code>
+mdadm /dev/md0 --fail /dev/sdb1 --remove /dev/sdb1 --add /dev/sdf1
+--- Add as hot spare, then replace/with, then remove failed
+mdadm /dev/md0 --add /dev/sdb1
+mdadm /dev/md0 --detail
+mdadm /dev/md0 --replace /dev/sdf1 --with /dev/sdb1
+mdadm /dev/md0 --remove /dev/sdf1
+mdadm --detail --scan > /etc/mdadm/mdadm.conf
+update-initramfs
+</code>
+===== Add a new disk to a existing raid =====
+  mdadm --manage /dev/md0 --add /dev/hdb1
+===== Rename a array =====
+  mdadm --stop /dev/md0
+  mdadm -A /dev/md6 -m0 --update=super-minor /dev/sda5 /dev/sdb5
+===== Boot auto assemble =====
+''If you have more then 4 raids then you need to pass the others to the kernel as it will not find these automatically.''
+<code>
+title Gentoo Linux 2.6.16-gentoo-r7.1
+        root (hd0,0)
+        kernel /kernel-2.6.16-gentoo-r7.1 root=/dev/md4 md=4,/dev/md0,/dev/md1 md=5,/dev/md2,/dev/md3
+</code>