Setup SAN Boot for RHEL 6.x using native multipath on EMC storage

Requirements:
1) RHEL 6.x (most apply to RHEL 5.x too, RHEL 5.x use mkinitrd instead of Dracut and the /etc/multipath.conf is slightly different refer to Red Hat KB in reference section)
2) EMC storage was setup with Active/Active (ALUA)
3) Boot LUN was presented with single path for initial install


Procedures:

1. Server boots up after initial install
2. Login to server as root to enable multipath
[root@server1]#mpathconf --enable –-with_multipathd y
3. Edit /etc/multipath.conf and make sure it only contains following valid parameters

blacklist {
}


defaults {
 user_friendly_names yes
}
devices {
  device {
    vendor "DGC"
    product ".*"
    product_blacklist "LUNZ"
    hardware_handler "1 alua"   
    path_checker directio    
    prio alua                
  }
}

4.Find out the logical path the root disk is mapped
[root@server1]#multipath –v3
It should be /dev/mapper/mpatha

5. Create initramfs with multipath module
[root@server1]#dracut --force -–add multipath

6. Make sure multipath.conf is included in initrd image

[root@server1]#lsinitrd /boot/initramfs-*.x86_64.img | grep multipath.conf
-rw-r--r--   1 root     root         2525 Feb 27 13:31 etc/multipath.conf

7. Modify the /boot/grub/device.map and change

 (hd0) /dev/sda    to
 (hd0) /dev/mapper/mpatha

This is assuming the boot disk is on /dev/mapper/mpatha as verified in step 2 above.

8. Reboot the server.

9. Verify multipath, check hwhandler='1 alua' and member disk sda for mpatha

[root@server1]#multipath –ll 
mpatha (3600601609973310067eb1e1ed69ae311) dm-0 DGC,VRAID
size=150G features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
`-+- policy='round-robin 0' prio=10 status=enabled
  |- 1:0:0:0 sda 8:0   active ready running
  

10. Ask storage administrator to enable other paths for boot LUN.
11. Reboot server again after multipath is aenabled in storage too
12. Login server to verify all paths, check hwhandler='1 alua' prio>0
if hwhandler='1 emc' or prio=0 means PNR mode

[root@server1]#multipath -ll
mpatha (3600601609973310067eb1e1ed69ae311) dm-0 DGC,VRAID
size=150G features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
|-+- policy='round-robin 0' prio=130 status=active
| |- 1:0:1:0 sdd 8:48  active ready running
| `- 2:0:1:0 sdj 8:144 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
  |- 1:0:0:0 sda 8:0   active ready running
  `- 2:0:0:0 sdg 8:96  active ready running
mpathb (360060160997331009fd6e124d69ae311) dm-1 DGC,VRAID
size=800G features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
|-+- policy='round-robin 0' prio=130 status=active
| |- 1:0:0:1 sdb 8:16  active ready running
| `- 2:0:0:1 sdh 8:112 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
  |- 1:0:1:1 sde 8:64  active ready running
  `- 2:0:1:1 sdk 8:160 active ready running

13. Partition other LUNS using fdisk command as normal, but use logical path /dev/mapper/mpathb etc (partition will be created as /dev/mapper/mpathbp1 instead of /dev/mapper/mpathb1
NOTE: any change to /etc/multipath.conf requires re-create initramfs ( dracut --force -–add multipath) and a reboot, because the boot LUN is on SAN, if boot LUN is local disk, change to /etc/multipath.conf only requires multipathd restart

Automate Server deployment with Ansible

There are many server automation applications in the market: puppet,chef,cfengine and salt. Ansible is relatively new, but I think it is better than puppet in server deployment automation tasks.
1. Dependency packages
Ansible depends on python, which is installed by default at least for Red Hat alike distributions
Puppet depends on ruby, which is not installed by default.
2. Agent
Ansible is agentless, it rely on SSH
Puppet need agent running in target server as a daemon.
3. Security
Ansible use SSH as transport method, so Username and password are required for each connection.(Ansible is smart enough to cache the SSH and sudo password, so it will be only prompted once for the first server)
Puppet: agent is controlled by master server, if master server is compromised, all hosts can be brought down easily
4. Setup
Ansible is easy to setup, as there is no agent. Ansible server is easy to setup too, there are just python scripts. You can even run it without installing it.
Puppet need packages installed in agent host or server, the agent certificate need to be signed before server can talk agent.
Ansible use SSH TCP port 22, which is standard firewall port already opened in most infrastructure.
Puppet use customized TCP port , typically 8139
5. Command line mode
Ansible supports command line mode for ad-hoc tasks, so you don’t need to write tasks definitions, just pass the command to ansbile such as return date for a number servers.
ansbile myservers –k –K –u admin –m raw –a “date”

The following example show a typical server deployment

[root@centos1 post]# cat setup.yml 
---        #ansible playbook use YAML syntax http://en.wikipedia.org/wiki/YAML
- hosts: server1          #It is a server or server group as defined in /etc/ansbile/hosts
  user: admin 
  sudo: yes
  vars_files:
    - vars/settings.yml   #global variables
    - vars/{{ ansible_hostname }}.yml             #server specific variable . ansible_hostname is variable, it is server1.yml for server1
  tasks:

  - name: yum
    action: yum name=${item}  state=present      #install yum packages
    with_items:
      - kernel-devel-{{ ansible_kernel }}
      - ed
      - ksh
      - ntp
  - script: ./scripts/sshd.sh        #- The script will insert 'UseDNS no' , - script is shorthand  for - name: XX ,action: YY

  - name: users | Delete users       #delete users delusers is list if users defined in setting.yml
    action: user name=$item state=absent
    with_items: delusers

  - name: ifcfg-eth0 | Configuration file      #ansible template engine is Jinja2 http://jinja.pocoo.org/docs/
    action: template src=./templates/ifcfg-eth0.j2 dest=/etc/sysconfig/network-scripts/ifcfg-eth0 owner=root group=root

  - name: route-eth0 | Configuration file, /etc/sysconfig/network-scripts/route-eth0
    action: template src=templates/route-eth0.j2 dest=/etc/sysconfig/network-scripts/route-eth0

  - name: resolv.conf | Configuration file, /etc/resolv.conf
    action: template src=templates/resolv.conf.j2 dest=/etc/resolv.conf

  - name: ntpd | Configuration file, /etc/ntp.conf
    action: template src=templates/ntp.conf.j2 dest=/etc/ntp.conf
    notify:
    - restart ntpd

  - name: snmpd | Configuration file, /etc/snmp/snmpd.conf
    action: copy src=files/snmpd.conf dest=/etc/snmp/snmpd.conf owner=root group=root mode=0644
    notify:
    - restart snmpd


  - copy: src=files/clock dest=/etc/sysconfig/clock owner=root group=root mode=0644
  - command: ln -fs /usr/share/zoneinfo/Australia/Sydney /etc/localtime


  handlers:
  - name: restart sshd
    action: service name=sshd enabled=yes state=restarted
  - name: restart ntpd
    action: service name=ntpd enabled=yes state=restarted
  - name: restart snmpd
    action: service name=snmpd enabled=yes state=restarted

####----Global variables 
[root@centos1 post]# cat vars/settings.yml 
#
# ntp.conf
ntpservers: [10.1.1.1, 10.1.1.2]

#users to delete
delusers: [user1, user2]

#resolv.conf
domainname: .example.com
searchdomain: [example.com]
nameservers: [10.1.1.1, 10.1.1.2]

####----Server specific  variable
[root@centos1 post]# cat vars/server1.yml 
eth1: 
   device: eth1
   ipaddr: 172.16.1.2
   netmask: 255.255.255.0
   routes: ['192.168.1.0/24 via 172.16.1.254', '192.168.2.0/24 via 172.16.1.254']
 
####----How the tempalate reference the variable
[root@centos1 post]# cat templates/resolv.conf.j2 
#
# resolver configuration file...
#
options         timeout:1 attempts:8 rotate
domain          {{domainname}}
search          {{domainname}} {{ searchdomain | join (' ') }}

{% for host in nameservers %}
nameserver {{host}}
{% endfor %}

[root@centos1 post]# cat templates/ifcfg-eth1.j2 
DEVICE={{eth1.device}}
BOOTPROTO=static
ONBOOT=yes
USERCTL=no
IPADDR={{eth1.ipaddr}}
NETMASK={{eth1.netmask}}
{% if eth1.gateway is defined  %} 
GATEWAY={{eth1.gateway}}
{%endif%}



####----a separate playbook to create LVM and file system 
[root@centos1 post]# cat setup-lvm.yml 
---
- hosts: server1
  user: admin
  sudo: yes
  gather_facts: no
  vars:
    mntp:  /opt
    vgname: vg01
    pvname: /dev/sdb1
    lv1: opt
 
  tasks:

  - script: ./scripts/disks.sh $pvname       #a script to create LVM partion and create physical volume
  - name: filesystem | Create pv,vg,lv and file systems
    action: lvg  vg=$vgname pvs=$pvname

  #- name: filesystem | create lv
  - lvol: vg=$vgname lv=$lv1 size=51196

 # - name: filesystem | create fs
  - filesystem: fstype=ext4 dev=/dev/${vgname}/${lv1}

  #- name: filesytem | mount dir
  - mount: name=${mntp} src=/dev/${vgname}/${lv1} dump=1 passno=2 fstype=ext4 state=mounted

How to run the playbook?

[root@centos1 post]# ansible-playbook -k -K setup.yml

  -k, --ask-pass        ask for SSH password
  -K, --ask-sudo-pass   ask for sudo password

Download all the files
https://drive.google.com/file/d/0B-RHmV4ubtk8Y2wyazhZRS1pSVk/edit?usp=sharing

VMware PowerCLI: Map datastore name to LUN devicename.

It is not obvious as it is thought to be to map datastore name to LUN devicename in native PowerCLI codes,
The  esxcli interface exposed to PowerCLI  make it very easy.(Tested in ESXi 5.0)

PowerCLI>$esxcli=get-esxcli -vmhost esx01
PowerCLI>$esxcli.storage.vmfs.extent.list() | ft devicename,volumename -autosize

DeviceName                           VolumeName
----------                           ----------
naa.600601605bc02e00007fb97cacbee211 datastore01
naa.600601605bc02e00fac8cd88acbee211 datastore02

Script to automatically partition a new disk and create LVM PV

It is a very common task to create a single partition on  whole disk  and create LVM PV, How to automate it?

fdisk doesn't support making partition in script mode, sfdisk can, but it is not as good as the powerful parted tool. parted can also optimize partition alignment automatically(parted -a optimal).

#!/bin/ksh
#Create a single primary partiton with whole disk size and create LVM PV on it
disk=$1
partno=1
if [[ -z $disk ]]; then
 echo "Usage: $0 disk device name: e.g $0 /dev/sdb"
 exit
fi


if [[ -e ${disk}${partno} ]]; then
 echo "==> ${disk}${partno} already exist"
 exit
fi

echo "==> Create MBR label"
parted -s $disk  mklabel msdos
ncyl=$(parted $disk unit cyl print  | sed -n 's/.*: \([0-9]*\)cyl/\1/p')

if [[ $ncyl != [0-9]* ]]; then
 echo "disk $disk has invalid cylinders number: $ncyl"
 exit
fi

echo "==> create primary parition  $partno with $ncyl cylinders"
parted -a optimal $disk mkpart primary 0cyl ${ncyl}cyl
echo "==> set partition $partno to type: lvm "
parted $disk set $partno lvm on
partprobe > /dev/null 2>&1
echo "==> create PV ${disk}${partno} "
pvcreate ${disk}${partno}

Understanding SysV-style Initscripts in Red Hat Linux

It is often needed to write your own init start/stop script, the following is the minimum requirement for your script to behave as expected. The discussion is based on Red Hat Linux family, other distributions like Debian use LSB (Linux Standard Base Specification) Init Scripts.

Location of the script

/etc/init.d is the well known location, but actually /etc/rc.d/init.d is the real original location. Since /etc/init.d is a hard link to /etc/rc.d/init.d, it makes no difference.

Header of the script

It needs at least 3 lines.  The shell script interpreter (/bin/sh, /bin/bash .. etc), the chkconfig header and script description

#!/bin/sh
#   chkconfig: 345 56 10
#   description: Startup/shutdown script for the Common UNIX 

Body of the script

Obviously, it need  to accept parameter “start”, which  /etc/rc3.d/S* will call  on OS startup and accept parameter “stop”, which /etc/rc0.d/K* script will call on OS shutdown.
The lockfile is often overlooked, it is used to check the existence of the daemon on OS shutdown, otherwise the stop action won’t be called. If you found an issue that a script started on OS startup but never stop properly on shutdown, you need to create lockfile. note: lockfile is not pidfile which contains PID of the process, lockfile is usually a blank file.

lockfile=/var/lock/subsys/$(basename $0)
case $1 in
 start)
  start
  [ $? = 0 ] && touch $lockfile
 ;;
 stop)
  stop
  [ $? = 0 ] && rf –f  $lockfile

Others

It is recommended to import functions in /etc/rc.d/init.d/functions to use ‘daemon’ to startup your application or killproc to shutdown your application instead of reinventing the wheel.

LSB headers

You may see something like this in an init script.

 # Provides: boot_facility_1 [ boot_facility_2 ...]
 # Required-Start: boot_facility_1 [ boot_facility_2 ...]
 # Required-Stop: boot_facility_1 [ boot_facility_2 ...]
 # Should-Start: boot_facility_1 [ boot_facility_2 ...]
 # Should-Stop: boot_facility_1 [ boot_facility_2 ...]
 # Default-Start: run_level_1 [ run_level_2 ...]
 # Default-Stop: run_level_1 [ run_level_2 ...]
 # Short-Description: short_description
 # Description: multiline_description

They are LSB(Linux Standard Base) headers, they are supported by default in Debian and SUSE Linux.
Red Hat Linux supports this by additional package “redhat-lsb” and it is not installed by default, Be warned,50+ dependences need to installed as well.

Reference

http://refspecs.linuxfoundation.org/LSB_2.1.0/LSB-generic/LSB-generic/initscrcomconv.html

https://fedoraproject.org/wiki/Packaging:SysVInitScript?rd=Packaging/SysVInitScript

Configure multipath on Solaris 11 for IBM V7000 SAN storage

IBM V7000 is not listed from command “mpathadm show mpath-support libmpscsi_vhci.so”, but it is still supported, Solaris 11 mpxio supports any third party storage device that is T10/T11 standards-compliant.
Procedures to setup multipath

#Setup zoning in SAN switch
#Login to V7000 management UI to map Solaris host to the volume, select host type ‘TPGS’
#Rescan new SAN disks without rebooting
$cfgadm -o force_update -c configure cX (X is the port id as shown cfgadm -al)
#verify SAN disks are detected.
$echo|format
#create scsi_vhci.conf
#scsi_vhci.conf doesn’t need to customized, scsi-vhci-failover-override parameter is optional, IBM V7000 is detected as f_tpgs with the standard probe.
$cp /kernel/drv/scsi_vhci.conf /etc/driver/drv/scsi_vhci.conf

#Obtain the device path of the fc ports of a single HBA
$ls -l /dev/cfg
lrwxrwxrwx   1 root     root          60 Feb 28 10:20 c4 -> ../../devices/pci@400/pci@2/pci@0/pci@8/SUNW,qlc@0/fp@0,0:fc
lrwxrwxrwx   1 root     root          62 Feb 28 10:20 c5 -> ../../devices/pci@400/pci@2/pci@0/pci@8/SUNW,qlc@0,1/fp@0,0:fc

the path needed is the string between ./devices/ and fp@, so the paths are  
/pci@400/pci@2/pci@0/pci@8/SUNW,qlc@0
/pci@400/pci@2/pci@0/pci@8/SUNW,qlc@0,1

#Create fp.conf
cp /kernel/drv/fp.conf /etc/driver/drv/fp.conf
#edit fp.conf to enable multipath for the two fc ports only
mpxio-disable="yes";
name="fp" parent="/pci@400/pci@2/pci@0/pci@8/SUNW,qlc@0" port=0 mpxio-disable="no";
name="fp" parent="/pci@400/pci@2/pci@0/pci@8/SUNW,qlc@0,1" port=0 mpxio-disable="no";
#run the command to enable multiple path on fc ports only, server will need to be rebooted.
$stmsboot –u –D fp

#verify 
$ echo| format will show only a single disk
$stmsboot -L
non-STMS device name                    STMS device name
------------------------------------------------------------------
/dev/rdsk/c4t50050768024046D8d0 /dev/rdsk/c0t6005076802830163A000000000000005d0
/dev/rdsk/c4t50050768022046D9d0 /dev/rdsk/c0t6005076802830163A000000000000005d0
/dev/rdsk/c5t50050768022046D8d0 /dev/rdsk/c0t6005076802830163A000000000000005d0
/dev/rdsk/c5t50050768024046D9d0 /dev/rdsk/c0t6005076802830163A000000000000005d0
$mpathadm list lu
        /dev/rdsk/c0t5000CCA0164251B8d0s2
                Total Path Count: 1
                Operational Path Count: 1
        /dev/rdsk/c0t5000CCA01642CDDCd0s2
                Total Path Count: 1
                Operational Path Count: 1
        /dev/rdsk/c0t6005076802830163A000000000000005d0s2
                Total Path Count: 4
                Operational Path Count: 4
$mpathadm show lu /dev/rdsk/c0t6005076802830163A000000000000005d0s2

#the disk is deteced as f_tpgs as shown in messages log
$grep f_ /var/adm/messages
Mar 21 13:56:46 dnmsovm1 scsi: [ID 583861 kern.info] ssd4 at scsi_vhci0: unit-address g6005076802830163a000000000000005: f_tpgs

Monitor customized application in Windows by SNMP

The native SNMP service  in Windows can provide basic metrics like CPU, memory and disk etc, but it doesn’t have “extend” feature in net-snmp, which allows you run a script for application monitoring. Net-snmp can’t be used as replacement for Windows SNMP service because some SNMP extension agent relies on it and known issue like HOST-RESOURCES MIB doesn’t work in net-snmp. 

 The good news is that you can have net-snmp co-exist with Windows SNMP, you can have nice features like extend ability, in the mean time, pass the other functions to native Windows SNMP service.

As of Net-SNMP 5.4, the Net-SNMP agent is able to load the Windows SNMP service extension DLLs by using the Net-SNMP winExtDLL extension. The extension requires the net-snmp binary to be native (32bit net-snmp extension won’t work in 64bit Windows).

Net-snmp 64bit binary is hard to find, it seems only net-snmp-5.5.0-2 has 64bit binary pre-compiled, you might need to compile yourself for other versions. 

Install net-snmp

Run the net-snmp binary installer select “with Windows Extenstion” instead of standard agent, unselect “net-snmp trap service” and “Perl SNMP modules”, the default path is c:\usr

Configure net-snmp

Register net-snmp as Windows service

Edit c:\usr\registeragent.bat to disable modules conflicting to Windows   by adding parameter.

“-I-udp,udpTable,tcp,tcpTable,icmp,ip,interfaces,snmp_mib”

(Note: if system_mib is also disabled, SNMPv2-MIB::sysuptime won’t report correct time)

Run c:\usr\registeragent.bat

Edit C:\usr\etc\snmp\snmpd.conf

rocommunity public 192.168.1.10
#Test extend feature to execute a script, the script path must use Unix style ‘/’
extend userscript c:/temp/test1.bat

Start Windows service “net-snmp agent”(Native SNMP service must be stopped)

Test

#Test standard SNMP metrics, the HOST-RESOURCES-MIB is provided by native SNMP service, not net-snmp
[root@zabbix]#/usr/bin/snmpwalk -v 2c  -c public 192.168.1.20   HOST-RESOURCES-MIB::hrSystemUptime
HOST-RESOURCES-MIB::hrSystemUptime.0 = Timeticks: (640892116) 74 days, 4:15:21.16

#The extend feature is provided by net-snmp, Execute the script by snmpwalk
[root@zabbix]#/usr/bin/snmpwalk -v 2c -Ov -c public 192.168.1.20 'NET-SNMP-EXTEND-MIB::nsExtendOutLine."userscript"'
STRING: web-time=80
STRING: web-status=[ok]

Troubleshooting

C:\usr\log\snmpd.log

Check which Windows modules loaded, start snmpd in command line with debugging “WinExtDLL”

Snmpd.exe -I-udp,udpTable,tcp,tcpTable,icmp,ip,interfaces,snmp_mib  -DwinExtDLL 

Reference:

http://net-snmp.sourceforge.net/docs/README.win32.html