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New DRBD Manage add-on for Highly Available storage

DRBD backed storage is now integrated into OpenNebula with the new DRBD Manage addon.

DRBD provides transparent, real-time replication of block devices without the need for specialty hardware. DRBD Manage is an administrative tool which facilitates easy Logical Volume Management (LVM) and configuration files for multi-node DRBD clusters.

With the DRBD Manage driver, create each new image for your virtual infrastructure as a DRBD volume. Volumes intelligently balance the load on your storage nodes. Alternatively, assign volumes to the specific nodes that you want in use. This is a simple scale-out storage solution, supporting the capability to add new nodes to your storage cluster at any time. This, combined with the flexibility of LVM, allows DRBD to keep up with your ever-increasing storage requirements.

DRBD 9 and DRBD Manage allow transferring Images to Virtualization hosts via the DRBD Transport protocol. This allows images to be available nearly instantly on host nodes without requiring them to have storage space available.

Below is a diagram showing a simple OpenNebula cluster using the DRBD Manage Driver. This cluster has a Front End, two storage nodes, and a single virtualization host. The host has two images attached to it via DRBD Transport. Both images are deployed to double redundancy and are being replicated in real time across both storage nodes. This means that the failure of a single storage node will not disrupt IO on the host. All nodes have a local copy of DRBD Manage’s control volume.

opennebula-diskless

Features

  • Data redundancy
  • Automatic fail-overs if a storage node fails
  • Database and high I/O application compatible
  • Transfers images over the network with DRBD Transport
  • Quickly attaches images to VMs
  • Fast image clones

Setting up High Availability in OpenNebula with LVM

In this post, I will explain how to install OpenNebula on two servers in a fully redundant environment. This is the English translation of an article in Italian on my blog.

The idea is to have two Cloud Controllers in High Availability (HA) active/passive mode using Pacemaker/Heartbeat. These nodes will also provide storage by exporting a DRBD partition via ATA-Over-Ethernet; the VM disks will be created on logical LVM volumes in this partition. This solution, besides being totally redundant, will provide high-speed storage because we use snapshots to deploy the partitions of the VM, not using files on an NFS filesystem.

Nonetheless, we will still use NFS to export the /srv/cloud directory with OpenNebula data.

System Configuration

As a reference, this is the configuration of our own servers. Your servers do not have to be exactly the same; we will simply be using these two servers to explain certain aspects of the configuration.

First Server:

  • Linux Ubuntu 64-bit server 10.10
  • Cards eth0 and eth1 configured with IP 172.17.0.251 bonding network (SAN)
  • ETH2 card with IP 172.16.0.251 (LAN)
  • 1 TB internal HD partitioned as follows:
    • sda1: 40 GB mounted on /
    • sda2: 8 GB swap
    • sda3: 1 GB for metadata
    • sda5: 40 GB for /srv/cloud/one
    • sda6: 850 GB datastore

Secondary Server

  • Linux Ubuntu 64-bit server 10.10
  • Cards eth0 and eth1 configured with IP 172.17.0.252 bonding network (SAN)
  • ETH2 card with IP 172.16.0.252 (LAN)
  • 1 TB internal HD partitioned as follows:
    • sda1: 40 GB mounted on /
    • sda2: 8 GB swap
    • sda3: 1 GB for metadata
    • sda5: 40 GB for /srv/cloud/one
    • sda6: 850 GB datastore

Installing the base system

Install Ubuntu server 64-bit 10.10 on the two servers and enabling OpenSSH server during installation. In our case, the servers are each equipped with a double-disk 1TB SATA in hardware mirror, on which we will create a 40 GB partition (sda1) for the root filesystem, a 4 GB (sda2) for the swap, a third ( sda3) of 1 GB formetadata , a fourth (sda5) with 40 GB for the directory /srv/cloud/one replicated by DRBD, and a fifth (sda6) with the remaining space (approximately 850 GB) that will be used by DRBD for the export of VM filesystems.

In terms of network cards, we have a total of three network cards to each server: 2 (eth0, eth1) will be configured in bonding to manage data replication and communicate with the compute nodes in the cluster network (SAN) on the class 172.17.0.0/24 and a third (eth2) is used to access from outside the cluster on the LAN 172.16.0.0/24 with class.

Unless otherwise specified, these instructions are specific to the above two hosts, but should work on your own system with minor modifications.

Network Configuration

First we modify the hosts file:

/etc/hosts
172.16.0.250 cloud-cc.lan.local cloud-cc
172.16.0.251 cloud-cc01.lan.local
172.16.0.252 cloud-cc02.lan.local
172.17.0.1 cloud-01.san.local
172.17.0.2 cloud-02.san.local
172.17.0.3 cloud-03.san.local
172.17.0.250 cloud-cc.san.local
172.17.0.251 cloud-cc01.san.local cloud-cc01
172.17.0.252 cloud-cc02.san.local cloud-cc02

Next, we proceed to the configuration of the system. First configure the bonding interface, installing required packages:

apt-get install ethtool ifenslave

Then we load the module at startup with correct parameters creating file /etc/modprobe.d/bonding.conf

/etc/modprobe.d/bonding.conf
alias bond0
bonding options mode=0 miimon=100 downdelay=200 updelay=200

And configuring LAN:

/etc/network/interfaces
auto bond0
iface bond0 inet static
bond_miimon  100
bond_mode balance-rr
address  172.17.0.251 # 172.17.0.251 on server 2
netmask  255.255.255.0
up /sbin/ifenslave bond0 eth0 eth1
down /sbin/ifenslave -d bond0 eth0 eth1

auto eth2
iface eth2 inet static
address  172.16.0.251 # 172.16.0.252 on server 2
netmask  255.255.255.0

Configuring MySQL

I prefer to configure a MySQL circular replication rather than to manage the launch of the service through HeartBeat because MySQL is so fast in the opening; having been active on both servers, they save a few seconds during the switch in case of a fault.

First we install MySQL:

apt-get install mysql-server libmysqlclient16-dev libmysqlclient

and create the database for OpenNebula:

mysql -p
create database opennebula;
create user oneadmin identified by 'oneadmin';
grant all on opennebula.* to 'oneadmin'@'%';
exit;

Then we configure active/active replica on server 1:

/etc/mysql/conf.d/replica.cnf @ Server 1
[mysqld]
bind-address			= 0.0.0.0
server-id                       = 10
auto_increment_increment        = 10
auto_increment_offset           = 1
master-host                     = server2.dominio.local
master-user                     = replicauser
master-password                 = replicapass
log_bin				= /var/log/mysql/mysql-bin.log
binlog_ignore_db		= mysql

And on server 2:

/etc/mysql/conf.d/replica.cnf @ server 2
[mysqld]
bind-address			= 0.0.0.0
server-id                       = 20
auto_increment_increment        = 10
auto_increment_offset           = 2
master-host                     = server1.dominio.local
master-user                     = replicauser
master-password                 = replicapass
log_bin				= /var/log/mysql/mysql-bin.log
binlog_ignore_db		= mysql

Finally, on both servers, restart mysql and create replica user:

create user 'replicauser'@'%.san.local' identified by 'replicapass';
grant replication slave on *.* to 'replicauser'@'%.dominio.local';
start slave;
show slave status\G;

DRBD Configuration

Now is the turn of DRBD but configured in standard active/passive. First install the needed packages:

apt-get install drbd8 modprobe drbd-utils

So let’s edit the configuration file:

/etc/drbd.d/global_common.conf
global {
usage-count yes;
# minor-count dialog-refresh disable-ip-verification
}

common {
protocol C;

handlers {
pri-on-incon-degr "/usr/lib/drbd/notify-pri-on-incon-degr.sh; /usr/lib/drbd/notify-emergency-reboot.sh; echo b > /proc/sysrq-trigger ; reboot -f";
pri-lost-after-sb "/usr/lib/drbd/notify-pri-lost-after-sb.sh; /usr/lib/drbd/notify-emergency-reboot.sh; echo b > /proc/sysrq-trigger ; reboot -f";
local-io-error "/usr/lib/drbd/notify-io-error.sh; /usr/lib/drbd/notify-emergency-shutdown.sh; echo o > /proc/sysrq-trigger ; halt -f";
# fence-peer "/usr/lib/drbd/crm-fence-peer.sh";
# split-brain "/usr/lib/drbd/notify-split-brain.sh root";
# out-of-sync "/usr/lib/drbd/notify-out-of-sync.sh root";
# before-resync-target "/usr/lib/drbd/snapshot-resync-target-lvm.sh -p 15 -- -c 16k";
# after-resync-target /usr/lib/drbd/unsnapshot-resync-target-lvm.sh;
}

startup {
# wfc-timeout degr-wfc-timeout outdated-wfc-timeout wait-after-sb
wfc-timeout 120; ## 2 min
degr-wfc-timeout 120; ## 2 minutes.
}

disk {
# on-io-error fencing use-bmbv no-disk-barrier no-disk-flushes
# no-disk-drain no-md-flushes max-bio-bvecs
on-io-error detach;
}

net {
# sndbuf-size rcvbuf-size timeout connect-int ping-int ping-timeout max-buffers
# max-epoch-size ko-count allow-two-primaries cram-hmac-alg shared-secret
# after-sb-0pri after-sb-1pri after-sb-2pri data-integrity-alg no-tcp-cork
# allow-two-primaries;
# after-sb-0pri discard-zero-changes;
# after-sb-1pri discard-secondary;

timeout 60;
connect-int 10;
ping-int 10;
max-buffers 2048;
max-epoch-size 2048;
}

syncer {
# rate after al-extents use-rle cpu-mask verify-alg csums-alg
rate 500M;
}
}

And let’s create one-disk definition:

/etc/drbd.d/one-disk.res 
resource one-disk {
    on cloud-cc01 {
	address 172.17.0.251:7791;
	device /dev/drbd1;
	disk /dev/sda5;
	meta-disk /dev/sda3[0];
    }
    on cloud-cc02 {
	address 172.17.0.252:7791;
	device /dev/drbd1;
	disk /dev/sda5;
	meta-disk /dev/sda3[0];
    }
}

and data-disk:

/etc/drbd.d/data-disk.res 
resource data-disk {
    on cloud-cc01 {
	address 172.17.0.251:7792;
	device /dev/drbd2;
	disk /dev/sda6;
	meta-disk /dev/sda3[1];
    }
    on cloud-cc02 {
	address 172.17.0.252:7792;
	device /dev/drbd2;
	disk /dev/sda6;
	meta-disk /dev/sda3[1];
    }
}

Now, on both nodes, we create the metadata disk:

drbdadm create-md one-disk
drbdadm create-md data-disk
/etc/init.d/drbd reload

Finally, only on server 1, activate the disk:

drbdadm -- --overwrite-data-of-peer primary one-disk
drbdadm -- --overwrite-data-of-peer primary data-disk

Exporting the disks

As already mentioned, the two DRBD partitions will be visible through the network, although in different ways: one-disk will be exported through NFS, data-disk will be exported by ATA-over-Ethernet and will present its LVM partitions to the hypervisor.

Install the packages:

apt-get install vblade nfs-common nfs-kernel-server nfs-common portmap

We’ll disable automatic NFS and AoE startup because we handle it via HeartBeat:

update-rc.d nfs-kernel-server disable
update-rc.d vblade disable

Then we create the export for OpenNebula directory:

/etc/exports
/srv/cloud/one          172.16.0.0/24(rw,fsid=0,insecure,no_subtree_check,async)

and we create necessary directory:

mkdir -p /srv/cloud/one

Finally we have to set idmapd daemon to correctly propagate user and permission on network.

/etc/idmapd.conf
[General]

Verbosity = 0
Pipefs-Directory = /var/lib/nfs/rpc_pipefs
Domain = lan.local # Modify this

[Mapping]

Nobody-User = nobody
Nobody-Group = nobody

Finally we have to configure default NFS settings:

/etc/default/nfs-kernel-server
NEED_SVCGSSD=no # no is default

and

/etc/default/nfs-common
NEED_IDMAPD=yes
NEED_GSSD=no # no is default

Fault Tolerant daemon configuration

There are two packages that can handle high available services on Linux: corosync and heartbeat. Personally I prefer heartbeat and provide instructions referring to this, but most configurations will be through the pacemaker, then you are perfectly free to opt for corosync.

First install the needed packages:

apt-get install heartbeat pacemaker

and configure heartbeat daemon:

/etc/ha.d/ha.cf
autojoin none
bcast bond0
warntime 3
deadtime 6
initdead 60
keepalive 1
node cluster-cc01
node cluster-cc02
crm respawn

Only on first server, we create the authkeys file, and will copy it on the second server:

( echo -ne "auth 1\n1 sha1 "; \
  dd if=/dev/urandom bs=512 count=1 | openssl md5 ) \
  > /etc/ha.d/authkeys
chmod 0600 /etc/ha.d/authkeys
scp /etc/ha.d/authkeys cloud-cc02:/etc/ha.d/
ssh cloud-cc02 chmod 0600 /etc/ha.d/authkeys
/etc/init.d/heartbeat restart
ssh cloud-02 /etc/init.d/heartbeat restart

After a minute or two, heartbeat will be online:

crm_mon -1 | grep Online
Online: [ cloud-cc0 cloud-cc02 ]

Now we’ll configure cluster services via pacemaker.
Setting default options:

crm configure
property no-quorum-policy=ignore
property stonith-enabled=false
property default-resource-stickiness=1000
commit
bye

The two shared IP 172.16.0.250 and 172.17.0.250:

crm configure
primitive lan_ip IPaddr params ip=172.16.0.250 cidr_netmask="255.255.255.0" nic="eth2" op monitor interval="40s" timeout="20s"
primitive san_ip IPaddr params ip=172.17.0.250 cidr_netmask="255.255.255.0" nic="bond0" op monitor interval="40s" timeout="20s"
commit
bye

The NFS export:

crm configure
primitive drbd_one ocf:linbit:drbd params drbd_resource="one-disk" op monitor interval="40s" timeout="20s"
ms ms_drbd_one drbd_one meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true"
commit
bye

The one-disk mount:

crm configure
primitive fs_one ocf:heartbeat:Filesystem params device="/dev/drbd/by-res/one-disk" directory="/srv/cloud/one" fstype="ext4"
commit
bye

The AoE export:

crm configure
primitive drbd_data ocf:linbit:drbd params drbd_resource="data-disk"  op monitor interval="40s" timeout="20s"
ms ms_drbd_data drbd_data meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true"
commit
bye

The data-disk mount:

crm configure
primitive aoe_data ocf:heartbeat:AoEtarget params device="/dev/drbd/by-res/data-disk" nic="bond0" shelf="0" slot=="0" op monitor interval="40s" timeout="20s"
commit
bye

Now we have to configure the correct order to startup services:

crm configure
group ha_group san_ip lan_ip fs_one nfs_one aoe_data
colocation ha_col inf: ha_group ms_drbd_one:Master ms_drbd_data:Master
order ha_after_drbd inf: ms_drbd_one:promote ms_drbd_data:promote ha_group:start
commit
bye

We will modify this configuration later to add OpenNebula and lighttpd startup.

LVM Configuration

LVM2 will allow us to create partitions for virtual machines and deploy it via snapshot basis.

Install the package on both machines.

apt-get install lvm2

We have to modify the filter configuration to allow lvm scan only to DRBD disk.

/etc/lvm/lvm.conf
...
filter = [ "a|drbd.*|", "r|.*|" ]
...
write_cache_state = 0

ATTENTION: Ubuntu uses a Ramdisk to bootup the system, so we have to modify also lvm.conf file inside ramdisk.

Now we remove the cache:

rm /etc/lvm/cache/.cache

Only on server 1 we have to create physical LVM volume and Volume Group:

pvcreate /dev/drbd/by-res/data-disk
vgcreate one-data /dev/drbd2

Install and configure OpenNebula

We are almost done. Now we download and install OpenNebula 2.2 via source:

First we have to install prerequisites:

apt-get install libsqlite3-dev libxmlrpc-c3-dev scons g++ ruby libopenssl-ruby libssl-dev ruby-dev make rake rubygems libxml-parser-ruby1.8 libxslt1-dev libxml2-dev genisoimage  libsqlite3-ruby libsqlite3-ruby1.8 rails thin
gem install nokogiri
gem install json
gem install sinatra
gem install rack
gem install thin
cd /usr/bin
ln -s rackup1.8 rackup

Then we have to create OpenNebula user and group:

groupadd cloud
useradd -d /srv/cloud/one  -s /bin/bash -g cloud -m oneadmin
chown -R oneadmin:cloud /srv/cloud/
chmod 775 /srv
id oneadmin # we have to use this id also on cluster node for oneadmin/cloud

Now we go in unpriviledged mode to create ssh certificate for cluster communications:

su - oneadmin
ssh-keygen # use default
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chown 640 ~/.ssh/authorized_keys
mkdir  ~/.one

We create a .profile file with default variables:

~/.profile
export ONE_AUTH='/srv/cloud/one/.one/one_auth'
export ONE_LOCATION='/srv/cloud/one'
export ONE_XMLRPC='http://localhost:2633/RPC2'
export PATH=$PATH':/srv/cloud/one/bin'

Now we have to create one_auth file to setup a default user inside OpenNebula (for example of api or sunstone):

~/.one/one_auth
oneadmin:password

And load default variables before compile:

source .profile

Now download and install OpenNebula:

cd
wget http://dev.opennebula.org/attachments/download/339/opennebula-2.2.tar.gz
tar zxvf opennebula-2.2.tar.gz
cd opennebula-2.2
scons -j2 mysql=yes
./install.sh -d /srv/cloud/one

About configuration: this is my oned.conf file, I use Xen HyperVisor, but you can use also KVM.

/src/cloud/one/etc/oned.conf
HOST_MONITORING_INTERVAL = 60

VM_POLLING_INTERVAL      = 60

VM_DIR=/srv/cloud/one/var

SCRIPTS_REMOTE_DIR=/var/tmp/one

PORT=2633

DB = [ backend = "mysql",
       server  = "localhost",
       port    = 0,
       user    = "oneadmin",
       passwd  = "oneadmin",
       db_name = "opennebula" ]

VNC_BASE_PORT = 5900

DEBUG_LEVEL=3

NETWORK_SIZE = 254

MAC_PREFIX   = "02:ab"

IMAGE_REPOSITORY_PATH = /srv/cloud/one/var/images
DEFAULT_IMAGE_TYPE    = "OS"
DEFAULT_DEVICE_PREFIX = "sd"

IM_MAD = [
    name       = "im_xen",
    executable = "one_im_ssh",
    arguments  = "xen" ]

VM_MAD = [
    name       = "vmm_xen",
    executable = "one_vmm_ssh",
    arguments  = "xen",
    default    = "vmm_ssh/vmm_ssh_xen.conf",
    type       = "xen" ]

TM_MAD = [
    name       = "tm_lvm",
    executable = "one_tm",
    arguments  = "tm_lvm/tm_lvm.conf" ]

HM_MAD = [
    executable = "one_hm" ]

VM_HOOK = [
    name      = "image",
    on        = "DONE",
    command   = "image.rb",
    arguments = "$VMID" ]

HOST_HOOK = [
    name      = "error",
    on        = "ERROR",
    command   = "host_error.rb",
    arguments = "$HID -r n",
    remote    = "no" ]

VM_HOOK = [
   name      = "on_failure_resubmit",
   on        = "FAILED",
   command   = "/usr/bin/env onevm resubmit",
   arguments = "$VMID" ]

The only important thing is to modify /srv/cloud/one/etc/tm_lvm/tm_lvm.rc setting default VG:

/srv/cloud/one/etc/tm_lvm/tm_lvm.rc
...
VG_NAME=one-data
...

Now copy the init.d script from source to /etc/init.d but not set it to startup ad boot.

I have modified the default script to startup also sunstone:

/etc/init.d/one
#! /bin/sh
### BEGIN INIT INFO
# Provides:          opennebula
# Required-Start:    $remote_fs
# Required-Stop:     $remote_fs
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: OpenNebula init script
# Description:       OpenNebula cloud initialisation script
### END INIT INFO

# Author: Soren Hansen - modified my Alberto Zuin

PATH=/sbin:/usr/sbin:/bin:/usr/bin:/srv/cloud/one
DESC="OpenNebula cloud"
NAME=one
SUNSTONE=/srv/cloud/one/bin/sunstone-server
DAEMON=/srv/cloud/one/bin/$NAME
DAEMON_ARGS=""
PIDFILE=/var/run/$NAME.pid
SCRIPTNAME=/etc/init.d/$NAME

# Exit if the package is not installed
[ -x "$DAEMON" ] || exit 0

# Load the VERBOSE setting and other rcS variables
. /lib/init/vars.sh

# Define LSB log_* functions.
# Depend on lsb-base (>= 3.0-6) to ensure that this file is present.
. /lib/lsb/init-functions

#
# Function that starts the daemon/service
#
do_start()
{
mkdir -p /var/run/one /var/lock/one
chown oneadmin /var/run/one /var/lock/one
su - oneadmin -s /bin/sh -c "$DAEMON start"
su - oneadmin -s /bin/sh -c "$SUNSTONE start"
}

#
# Function that stops the daemon/service
#
do_stop()
{
su - oneadmin -s /bin/sh -c "$SUNSTONE stop"
su - oneadmin -s /bin/sh -c "$DAEMON stop"
}

case "$1" in
start)
[ "$VERBOSE" != no ] && log_daemon_msg "Starting $DESC" "$NAME"
do_start
case "$?" in
0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
esac
;;
stop)
[ "$VERBOSE" != no ] && log_daemon_msg "Stopping $DESC" "$NAME"
do_stop
case "$?" in
0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
esac
;;
restart|force-reload)
#
# If the "reload" option is implemented then remove the
# 'force-reload' alias
#
log_daemon_msg "Restarting $DESC" "$NAME"
do_stop
case "$?" in
0|1)
do_start
case "$?" in
0) log_end_msg 0 ;;
1) log_end_msg 1 ;; # Old process is still running
*) log_end_msg 1 ;; # Failed to start
esac
;;
*)
# Failed to stop
log_end_msg 1
;;
esac
;;
*)
echo "Usage: $SCRIPTNAME {start|stop|restart|force-reload}" >&2
exit 3
;;
esac

:

and set it with execute permissions:

chmod 755 /etc/init.d/one

Configuring the HTTPS proxy for Sunstone

Sunstone is the web interface for Cloud administration, if you do not want to use the command line… works on port 4567 and is not encrypted, so we’ll use lighttpd for proxy requests to HTTPS encrypted connection.

First install the daemon:

apt-get install ssl-cert lighttpd

Then generate certificates:

/usr/sbin/make-ssl-cert generate-default-snakeoil
cat /etc/ssl/private/ssl-cert-snakeoil.key /etc/ssl/certs/ssl-cert-snakeoil.pem > /etc/lighttpd/server.pem

and create symlinks to enable ssl and proxy modules:

ln -s /etc/lighttpd/conf-available/10-ssl.conf /etc/lighttpd/conf-enabled/
ln -s /etc/lighttpd/conf-available/10-proxy.conf /etc/lighttpd/conf-enabled/

And modify lighttp setup to enable proxy to sunstone:

/etc/lighttpd/conf-available/10-proxy.conf
proxy.server               = ( "" =>
                                ("" =>
                		(
                                 "host" => "127.0.0.1",
                                 "port" => 4567
                                )
                                )
                            )

Starting LightHTTP and OpenNebula with heartbeat

Now add the startup script automatically to heartbeat. First all stop heartbeat on both servers:

crm node
standby cloud-cc01
standby cloud-cc02
bye

Then we can change the configuration:

crm configure
primitive OpenNebula lsb:one
primitive lighttpd lsb:lighttpd
delete ha_group
group ha_group san_ip lan_ip fs_one nfs_one aoe_data OpenNebula lighttpd
colocation ha_col inf: ha_group ms_drbd_one:Master ms_drbd_data:Master
order ha_after_drbd inf: ms_drbd_one:promote ms_drbd_data:promote ha_group:start
commit
bye

And startup the cluster again:

crm node
online cloud-cc01
online cloud-cc02
bye

That’s all folks!
Thanks,
Alberto Zuin – http://www.anzs.it