Increase stripe_cache_size for mdadm/md devices permanently

Posted in Uncategorized on May 26th, 2017 by termina

Create /etc/udev/rules.d/60-md-stripe-cache.rules

SUBSYSTEM=="block", KERNEL=="md*", ACTION=="change", TEST=="md/stripe_cache_size", ATTR{md/stripe_cache_size}="16384"

Reload udev rules, will take effect immediately.

udevadm control --reload-rules

udevadm trigger

Confirm (where md0 is your md device in question)

cat /sys/devices/virtual/block/md0/md/stripe_cache_size

ESXi 5.5 and Teaming on Cisco Switches (VLANs)

Posted in ESX, Networking on November 22nd, 2016 by termina


Create a basic port channel

interface Port-channel1
description ESX Port Channel
switchport mode trunk

interface GigabitEthernet0/8
description ESX team
channel-group 1 mode on
spanning-tree portfast trunk

interface GigabitEthernet0/9
description ESX team
channel-group 1 mode on
spanning-tree portfast trunk

Configure NIC teaming (Configuration – Network – Properties – vSwitch Properties) with the following settings

Load Balancing: Route based on IP address

Network Failover Detection: Link status only

Notify Switche: Yes

Failback: No


When you’re happy with the results, update your Management network settings to use NIC teaming as well.


Raspberry PI Phone Home

Posted in Networking on November 15th, 2016 by termina

This can be done on any systemd based system, this example is on a Raspberry PI running Raspbian (jessie).

# apt-get install autossh

Generate SSH key and copy it over

# ssh-keygen

# ssh-copy-id [email protected]

Create /etc/systemd/system/autossh.service


Description=AutoSSH service

ExecStart=/usr/bin/autossh -M 0 -f -N -T -q -o ServerAliveInterval=30 -o ServerAliveCountMax=3 -R 9993:localhost:22 [email protected]


Reload systemd

# systemctl daemon-reload

Enable/Start Service

# systemctl enable autossh

# systemctl start autossh

Now from “server” you should be able to reach your PI

# ssh localhost -p 9993



GlusterFS MySQL my.cnf Settings

Posted in Uncategorized on November 29th, 2015 by termina

This doesn’t seem to be clearly documented, but to make this persistent add the following under your [mysqld] section of my.cnf


external_locking = TRUE
delay_key_write = Off
query_cache_size = 0

HA Linux Mail Server – Part 2 (RHCS Postfix/Dovecot/MySQL)

Posted in Clusters on December 25th, 2014 by termina

Now it’s fine to configure our services.

On both nodes install and disable these services (cluster services will manage starting/stopping)

yum install postfix mysqld dovecot

chkconfig postfix off

chkconfig mysqld off

chkconfig dovecot off

Copy the required data to our shared glusterfs storage.

cp -rp /var/lib/mysql /mysql/data/

cp -p /etc/my.cnf /mysql/data

cp -rp /etc/postfix /mail/data

cp -rp /etc/dovecot /mail/dovecot

cp -p /etc/init.d/postfix /mail/data/

cp -p /etc/init.d/dovecot /mail/data/

mkdir /mail/data/vmail

/mail/data/vmail will hold our user mail, otherwise we are making sure that our configuration files are located on the shared storage so we have a consistent environment.

Update /mysql/data/my.cnf with


Create /mail/data/ since our cluster service needs to call both postfix and dovecot.

if [ "$1" == "status" ]; then
ps -ef | grep -v grep | grep "/usr/libexec/postfix/master"
exit $?
/mail/data/ $1; /mail/data/ $1
exit 0

Please note this is a quick and dirty hack. You should have more checks than just master running since we care about dovecot as well.

Now again on both nodes, make some symbolic links to the shared storage for our services.

mv /etc/postfix /etc/postfix.bak

ln -s /mail/data/postfix /etc/postfix

mv /etc/dovecot /etc/dovecot.bak

ln -s /mail/data/dovecot /etc/dovecot

You should now be able to start your services. If you run into any errors, check /var/log/messages or /var/log/cluster/cluster.log

clusvcadm -d postfix-svc

clusvcadm -d mysql-svc

clusvcadm -e postfix-svc

clusvcadm -e mysql-svc

To store users mail in /mail/data/vmail, make the following changes to /etc/postfix/ – in this example we are using LDAP.

Both nodes in this case are replicating LDAP information from another server, so both the main LDAP server and one node could go down and users could still authenticate to the cluster services.

accounts_server_host = localhost
accounts_search_base = dc=example,dc=com
#Assumes users have a mail: attribute, if not use something else
accounts_query_filter = (mail=%u)
#accounts_result_attribute = homeDirectory
accounts_result_attribute = mail
#accounts_result_format  =  %u/Mailbox
accounts_result_format  = /var/vmail/%u/
accounts_scope = sub
accounts_cache = yes
accounts_bind = yes
accounts_bind_dn = cn=admin,dc=example,dc=com
accounts_bind_pw = PASSWORD
accounts_version = 3

virtual_transport = virtual
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000
virtual_mailbox_base = /
virtual_mailbox_maps = ldap:accounts
virtual_mailbox_domains =

For Dovecot, configure LDAP normally and then make the following changes

conf.d/auth-ldap.conf.ext:  args = uid=vmail gid=vmail home=/var/vmail/%u/
conf.d/10-mail.conf:mail_location = maildir:/var/vmail/%u
dovecot.conf:mail_location = maildir:/var/vmail/%u

Once this is done, restart your services (clusvcadm -R servicename) and send some test e-mails to yourself.

HA Linux Mail Server – Part 1 (RHCS CentOS 6/Glusterfs)

Posted in Clusters on December 25th, 2014 by termina

Things needed for RHCS on Centos 6

  • Two Centos 6 nodes
  • Shared storage (glusterfs)
  • Fencing mechinism (in our case, a custom fence_esxi found on this website)

I have two physical ESXi 5.1 servers, so the below will assume ESXi for fencing.

Install and configure glusterfs

I assume you have added additional disks to your VM for this (sdb, sdc)

Add the EPEL/EL repos for your distruction to /etc/yum.repos.d

yum install glusterfs glusterfs-server

Partition and format /dev/sdb1 and /dev/sdb2 as EXT4, adding the following to /etc/fstab ON BOTH NODES

In the below example, I am using LVM

/dev/vg01/mysql         /mysql                   ext4    defaults        0 0
localhost:/gv0          /mysql/data             glusterfs       defaults 0 0
/dev/vg02/mail          /mail                   ext4    defaults        0 0
localhost:/gv1          /mail/data              glusterfs       defaults 0 0

Mount /mysql and /mail (not /*/data yet)

Now on only one node, do the following commands

gluster volume create gv0 replica 2 transport tcp centos-cluster1:/mysql/brick centos-cluster2:/mysql/brick

gluster volume start gv0

gluster volume create gv1 replica 2 transport tcp centos-cluster1:/mail/brick centos-cluster2:/mail/brick

gluster volume start gv1

You should now be able to mount /mail/data and /mysql/data on both nodes.


Install RHCS and tools on both nodes

yum install luci ricci rgmanager cman fence-agents corosync

Once done with this step, make sure both node has the other node in their /etc/hosts file and configure your nodes to use static IPs.

Use luci to create the basic configuration of your cluster.  (https://NODE1IP:8084)

Manage Cluster – Add

Once created add your nodes under “Nodes”

Create your fence devices (Use fence_vmware or something similar for now, we will change it later most likely) for each ESXi server.

Create a failover domain (Prioritized=No, Restricted=No)

Create two IP address resources (one for mail services, one for mysql)

Finally create your service groups for each service.

Order should be: IP Resource – Service

For your postfix-svc, use the “Script” type and define the script file as /mail/data/

For mysql-svc, use the “Mysql” type and use for the Config File: /mysql/data/my.cnf

You should now be able to run “clustat” on either node, although your services will be failed or disabled for now.

Finally, let’s finish up fencing.

See for ESXi 5.1 (if you’re using something else, you’ll have to do this part yourself I’m afraid)

Test fencing with the “fence_node” command. Do not skip this step! Make sure fencing works before moving forward.

HA Linux Mail Server – Part 0

Posted in Clusters, HowTo, LDAP, Services on December 5th, 2014 by termina

I’ve been working on a project to learn more about RHCS in general and decided to build a HA Mail server.

Technologies Used:
– Centos 6.6
– Postfix
– Dovecot (IMAP)
– OpenLDAP
– GlusterFS
– Roundcube

Over the coming weeks I’ll be posting the steps required to set this up.

The general idea is to have two RHCS services


  • VIP for postfix/dovecot
  • glusterfs for delivered mail, postfix and dovecot configuration files


  • VIP for mysql
  • glusterfs for mysql config and data


Each node runs the following locally

  • httpd + roundcube
  • OpenLDAP replicating from another LDAP server

While the above two services could certainly be cluster services, this is not required.

We NAT our public IP to the VIP for mail-svc.

To avoid SSH key issues, copy your SSH keys from /etc/ssh to the other node (So SSH to the public IP will not result in errors after a failover)



RHCS ESXi 5.1 Fencing

Posted in Clusters, ESX on November 6th, 2014 by termina

Turns out that using the “free” version of ESXi 5.1 does not work with RHCS fencing due to SOAP limitations.

Place the following file in /usr/sbin/fence_esxi and chmod a+x /usr/sbin/fence_esxi

Make sure to install paramiko (yum install python-paramiko)


import paramiko
import sys
import time
import datetime
import re
from fencing import *

device_opt = [  "help", "version", "agent", "quiet", "verbose", "debug", "action", "ipaddr", "login", "passwd", "passwd_script", "ssl", "port", "uuid", "separator", "ipport", "power_timeout", "shell_timeout", "login_timeout", "power_wait" ]

options = check_input(device_opt, process_input(device_opt))

f = open("/var/log/cluster/fence_esxi.log","w+")
ts = time.time()
st = datetime.datetime.fromtimestamp(ts).strftime('%Y-%m-%d %H:%M:%S')
f.write(st + " starting fencing.\n")
f.write("-n " + options["-n"] + "\n")
f.write("-a " + options["-a"] + "\n")
f.write("-l " + options["-l"] + "\n")
f.write("-p " + options["-p"] + "\n")

client = paramiko.SSHClient()

command="esxcli vm process list | grep ^" + options["-n"]  + " -A 1 | tail -n 1 | sed \'s/  */ /g\' | cut -d \" \" -f 4"

f.write("Cmd: " + command + "\n")

stdin, stdout, stderr = client.exec_command(command)
while not
        f.write("Waiting for command to finish... \n")

wwid =
f.write("wwid: " + wwid + "\n")

if len(wwid) < 2:
	f.write("VM not found or alread offline \n")

f.write("VM found \n")
command="esxcli vm process kill --type=soft --world-id=" + wwid
f.write("Cmd: " + command + "\n")

stdin, stdout, stderr = client.exec_command(command)
while not
        f.write("Waiting for command to finish... \n")

#Give the VM some time to shut down gracefully
f.write("Waited 30 seconds \n")

command="vm-support -V | grep centos | cut -d \"(\" -f 2 | cut -d \")\" -f 1"
f.write("Cmd: " + command + "\n")

stdin, stdout, stderr = client.exec_command(command)
while not
        f.write("Waiting for command to finish... \n")

status =
f.write("VM Status: " + status + "\n")
sregex = re.compile('Running')

	f.write("VM still running, hard kill required \n")
	command="esxcli vm process kill --type=hard --world-id=" + wwid
	f.write("Cmd: " + command + "\n")
	stdin, stdout, stderr = client.exec_command(command)
	while not
	        f.write("Waiting for command to finish... \n")

	f.write("VM successfully soft killed \n")

#Get VM info while powered off
command="vim-cmd vmsvc/getallvms | grep " + options["-n"] + " | sed 's/  */ /g' | cut -d \" \" -f 1"
f.write("Cmd: " + command + "\n")
stdin, stdout, stderr = client.exec_command(command)
while not
        f.write("Waiting for command to finish... \n")

vmid =

#Start VM back up
command="vim-cmd vmsvc/power.on " + vmid
f.write("Cmd: " + command + "\n")
stdin, stdout, stderr = client.exec_command(command)

while not
	f.write("Waiting for command to finish... \n")

f.write("fence_esxi exiting...")

In your cluster.conf you would then have something like the following. Make sure to enable SSH on your ESXi hosts

<method name="fence-cluster1">
<device name="esx1" port="centos-cluster1" ssl="on" />

<fencedevice agent=”fence_esxi” ipaddr=”” login=”root” name=”esx2″ passwd=”YOURPASSWORDHERE” delay=”60″ />

OpenLDAP SSL Replication

Posted in LDAP on October 19th, 2014 by termina

Following the excellent guide here:

I was able to get LDAP replication working fairly easily. There are two problems with this however.

1. The default slapd configuration will use dc=nodomain (if no domain was picked at install) otherwise whatever domain you picked at install. You are not asked to choose, so of course if you have a different domain than your LDAP server replication will not function.

2. The above guide does NOT use SSL for replication for some reason

On your client, do the following to change dc=nodomain to whatever it should be for replication

/etc/init.d/slapd stop
rm /var/lib/ldap/*
vi /etc/ldap/slapd.d/cn\=config/olcDatabase\=\{1\}hdb.ldif

Update all dc=nodomain entries to dc=your,dc=domain

Then start slapd

/etc/init.d/slapd start

Create an LDIF file like the following (in this case, mirror.ldif)

dn: olcDatabase={1}hdb,cn=config
changeType: modify
add: olcSyncrepl
olcSyncrepl: rid=004 provider=ldaps://YOURMASTERHOSTNAME:636 bindmethod=simple binddn="cn=mirrormode,dc=bbis,dc=us" credentials=YOURPASSWORD tls_reqcert=never searchbase="dc=bbis,dc=us" schemachecking=on type=refreshAndPersist retry="60 +"
add: olcMirrorMode
olcMirrorMode: TRUE

Note that “rid=004” should be different for each LDAP server you bring in to play. Replace dc=bbis,dc=us with your domain.

Now add it to your schema

ldapmodify -QY EXTERNAL -H ldapi:/// -f mirror.ldif

Use ldapsearch to verify functonality

ldapsearch -H ldap:// -x

Cisco IOS Import Wildcard Certificate

Posted in Uncategorized on April 30th, 2014 by termina

crypto ca trustpoint comodo
enrollment terminal
chain-validation stop
revocation-check none

crypto ca authenticate comodo
[Comodo ROOT CA]

crypto ca import comodo pkcs12 tftp: password PASSWORDYOUUSED
[Exported PFX]