Raid 5 simplified

Just visited below page on youtube.

Must admit the video uploader has explained raid 5 very well.

http://www.youtube.com/watch?v=LTq4pGZtzho

On next video you can see how raid 5 works with more than 3 disks (in this case 4).

OVS repositories are not mounted after server reboot.

repositories are not getting initialized after server reboot.

It has been observed in OVM 2.2.1 that after the server reboot repositories are not getting initialized.

After checking the log files i came to know that Network was unreachable during the initial ovs-agent startup.

So we have made some manual changes to make sure first the server should be in network and then the ovs-agent should be started.

Created a script called ovs-repo and saved it in /etc/init.d

# cat /etc/init.d/ovs-repo
#!/bin/sh
# chkconfig: 2345 99 02
# description: restart ovs agent
#

echo "Waiting for 30 sec's for ovs repository initialization"
sleep 60
service ovs-agent stop
service ovs-agent start

Later created soft link in /etc/rc3.d/
#ln -s /etc/init.d/ovs-repo /etc/rc3.d/S99ovs-repo

added the service in chkconfig
#chkconfig --add ovs-repo

Difference between HVM and PVM

A very good article explaining the difference between Hardware virtualized machine and Paravirtual machine is given below.

The article helped me understand how PV machines are faster than HV machines?

http://serverfault.com/questions/222010/difference-between-xen-pv-xen-kvm-and-hvm