REDUNDANCY

Dr. John P. AbrahamProfessor

UTPA

This slide series is a summary of what we discussed in class.

• Power• Broadband• Hard Drive• Backup• Cluster

Power Supply Redundancy

• Power Source– AC– Generator– Solar

AC

• Problem with spikes and browns• Should not have other appliances or devices

connected to it.• Should have a direct circuit breaker• Use surge protection for the whole circuit.• I looked up Square D surge protector as an

example.• Such outlets should be color coded (Orange or

Red)

Generator

• Should maintain it properly. Must start it each week

• Need to have a transfer switch. There is a time delay. Meanwhile your computer will go off.

Solar with Battery back up

• Need to have pure sine wave inverters to be used with electronic equipment.

• You can connect these batteries to the UPS• Solar Array needs to have a voltage controller,

to keep it from over charging the batteries.• Also needs to have a transfer switch.• You can also use APC Redundant Automatic

Transfer switch or similar ones

UPS

• A must for all servers• Check the voltage and wattage rating• VA stands for voltage Amp – How much load a

UPS can handle at any given time. This will tell you how many devices can be plugged in.

UPS software

• APC powerchute software• Powercom• Powershield• Notifies the server of the remaining power• Notifies administrator through text or email• Sends message to clients• Closes files and shuts down

Broadband redundancy• Determine highest speed you would need and

that should become your primary broadband.• Determine the lowest speed you can get by

without damaging your business much, make that your secondary broadband.

• Both services should provided you with pool of public IP addresses.

• Assign one of those IP addresses to appropriate router or modem. In case of a modem the public IP should be passed on or bridged to the load balancer discussed below.

Redundancy and load balancer

• Purchase a router that is capable of load balancing.

• All Private LAN traffic should go through this router.

• A load balancer will have more than one WAN port. Assign appropriate public IPs to each of the WAN. Appropriate means the IP address should come from the appropriate service connected to the WAN port.

Stand by WAN service

• If the primary fails then the secondary should take over

Load balancing

• If either the download speed or the upload speed is similar you may want to load balance.

• Set appropriate policies for load balancing. For example, you may want to set a policy for secure connections to go through a designated WAN.

RAID

• We discussed different levels of RAIDs and advantage and disadvantage of each.

• Get hot pluggable hard drives, that way you won’t have to bring the system down.

• RAID in itself does not assure you protection against corruption.

• Must use backup along with RAID

Redundant Array of Inexpensive Servers

• RAIS stripes and mirrors application code and memory across an array of ordinary servers using the standard RAID schemata of level 0, level 1, level 5, level 1+0. This is possible through the invention of a radical new memory management system called Versioned Memory.

• However, I want to start with the old fashioned way of achieving redundancy.

Backups

• Backup must on removable media, either tape drive or removable hard drive.

• Discussed full and incremental backups• Discussed rotation schedule. Must have a

removable media for each day, and for each week. The weekly must go to fire proof vault.

• Remote backups• Cloud backup – consider financial investment

Cluster