Adding RBD support for Xen

Ceph 是近來新興的分散式檔案系統, 作者網站號稱可以到 peta-byte 的處理能力
看他的架構的確是不錯, 但目前還在開發階段, 不宜作為 production 使用!!
以下是小弟寫的小小 script 讓 xen 也能使用 Ceph 的 Rados

Adding the follow code in /etc/xen/scripts/block-rbd

#!/bin/bash

# Usage: block-rbd [monitor_server options pool_name image_name]

dir=$(dirname "$0")
. "$dir/block-common.sh"
rbd="/sys/bus/rbd/devices"

case "$command" in
 add)
   echo "$2 $3 $4 $5" > /sys/bus/rbd/add
   sleep 0.5
   for dev in `ls $rbd`; do
       if [ "`cat $rbd/$dev/pool`" == $4 ] && [ "`cat $rbd/$dev/name`" == $5 ]; then
         write_dev "/dev/rbd$dev"
         xenstore_write "$XENBUS_PATH/rbd" "$dev"
         exit 0
       fi
   done
   exit 1
   ;;
 remove)
   dev=$(xenstore_read "$XENBUS_PATH/rbd")
   echo $dev > /sys/bus/rbd/remove
   ;;
esac

Modify the last line of /etc/xen/scripts/block

--- block.org       2006-11-13 15:13:37.000000000 +0100
+++ block      2010-12-24 20:55:10.000000000 +0800
@@ -404,4 +404,4 @@

# If we've reached here, $t is neither phy nor file, so fire a helper script.
[ -x /etc/xen/scripts/block-"$t" ] && \
-  /etc/xen/scripts/block-"$t" "$command" $node
+  /etc/xen/scripts/block-"$t" "$command" $p

Creating new config file for VM

The format of new block device is "rbd:monitor_server options pool_name image_name". example:

kernel = "/mnt/images/gentoo/kernel/boot/vmlinuz-2.6.32.26-domu"
extra = "root=/dev/xvda1 ro console=hvc0 ip=::::vm01::off"
memory = 1024
vcpus = 2
name = "vm01"
vif = [ '' ]
disk = [ 'rbd:192.168.15.1 name=admin rbd gentoo.2010-0.x86-64.img,xvda1,w' ]