add documentation for removing a device from linux kernel safely

Signed-off-by: Martin Zobel-Helas <zobel@ftbfs.de>

diff --git a/input/howto/decomission.mdwn b/input/howto/decomission.mdwn
index ce2da3c..da732e5 100644 (file)
--- a/input/howto/decomission.mdwn
+++ b/input/howto/decomission.mdwn
@@ -28,6 +28,33 @@
     rabbitmqadmin -N rainier -V dsa delete queue name=$queue
     done
 
-Three months after decomissioning:
+ * Remove disks from the MSA 
+   * run multipath -ll on the KVM host and find all disks on that multipath
+
+```
+    finzi-srv (3600c0ff00027786c874edd5701000000) dm-52 HP,MSA 2040 SAN
+    size=75G features='2 queue_if_no_path retain_attached_hw_handler' hwhandler='0' wp=rw
+    |-+- policy='service-time 0' prio=50 status=active
+    | |- 1:0:2:4  sdeu 129:96  active ready running
+    | |- 1:0:3:4  sdhu 134:64  active ready running
+    | |- 2:0:0:4  sdaa 65:160  active ready running
+    | `- 2:0:2:4  sdfz 131:80  active ready running
+    `-+- policy='service-time 0' prio=10 status=enabled
+      |- 1:0:0:4  sdf  8:80    active ready running
+      |- 1:0:1:4  sdbu 68:128  active ready running
+      |- 2:0:1:4  sdcz 70:112  active ready running
+      `- 2:0:3:4  sdja 8:320   active ready running
+   
+```
+   * for each disk in those multipath run
+
+     echo 1 > /sys/block/sdX/device/delete
+
+   * once done, remove that multpath-device from multipath
+
+     multipath -f finzi-srv
+
+   * remove the paths in the MSA
 
+Three months after decomissioning:
  * Remove backups