Category Archives: Linux

Adding to my post from monday, I had another issue with SRM not changing ip addresses on an Asterisk (CentOS) box, so I had to engineer a workaround..

For PRIMARY = 10.100.1.150 and DR = 10.100.2.150

1. On the linux box, we’ll create two bash scripts, chmod these 755 and stick these in your $PATH.

primary-to-dr.sh
#!/bin/sh
ifconfig eth0 10.100.2.150 netmask 255.255.255.0 up
route add default gw 10.100.2.1 eth0
done

dr-to-primary.sh
#!/bin/sh
ifconfig eth0 10.100.1.150 netmask 255.255.255.0 up
route add default gw 10.100.1.1 eth0
done

2. On the vCenter, install WinSCP and run. Create 2 new sessions with saved credentials and name primary and dr. Connect to each session and accept the certificates!
3. Ensure the following is in the windows PATH, if not, add this directory: C:Program Files (x86)WinSCP
4. Create the batch file below to call winscp, start the session and run the relevant script from step 1.

ifconfig.bat
@echo off
echo “Logging into host and running script”
If EXIST c:primary.txt (winscp primary /command “call primary-to-dr.sh”) ELSE (winscp dr /command “call dr-to-primary.sh”)
echo Exit Value %ERRORLEVEL%
TIMEOUT /t 5 /nobreak

In SRM run the bat file, no flags needed.

VMware advertises the ability to “perform fully automated orchestration of site failover and fallback with a single click.” While this technology is extremely easy to setup and use, it’s oftentimes the small things that cause the biggest headache. SRM uses dns to propogate ip changes from the primary to secondary virtual machines. With windows this is automatic: the servers simply register their new ip addresses in dns. For linux servers, however this is not so easy, especially in my case (an avaya phone system) which provides no access to the CLI. The fix is to create a script.

DNS Server – 192.168.10.1
Primary Site Avaya – 192.168.10.35
Failover Site Avaya- 192.168.15.35

First you’ll want to make sure you are running the SRM service as an account with domain admin rights (assuming you setup the database with windows authentication during setup).

Next you’ll need DNSCMD from the RSAT (remote server administration tools), which you can find here

Below is an example script:

@echo OFF
echo “Removing Records from DNS…”
dnscmd 192.168.10.1 /recorddelete dom.local AVAYA-SRV-01 A /f
echo Exit Value:  %ERRORLEVEL%
TIMEOUT /t 3 /nobreak
dnscmd 192.168.10.1 /recorddelete dom.local AVAYA-SRV-01 A /f
echo Exit Value:  %ERRORLEVEL%
TIMEOUT /t 3 /nobreak

@echo off
echo “Adding Records to DNS ..”
If EXIST c:primary.txt (dnscmd 192.168.10.1 /recordadd dom.local AVAYA-SRV-01 A 192.168.10.35) ELSE (dnscmd 192.168.16.58 /recordadd dom.local AVAYA-SRV-01 A 192.168.15.35)
echo Exit Value:  %ERRORLEVEL%
TIMEOUT /t 5 /nobreak

In SRM, you’ll call the script as:
C:windowssystem32cmd.exe /c c:srmscriptsdnschange.bat

Also, you may notice the “If EXIST c:primary.txt”
It was the most elegant way I could think of the check if the system was in a failover state. This file will exist only on the primary side. Credit to Derek Bickel on this one!