Recovery position
Wouter Vancoppenolle, regional sales director for eastern Europe, Middle East and Africa of Double-Take Software, explains four possible options for disaster recovery for your virtual environment.
Published Wednesday, 21 July 2010
By Imthishan Giado
Virtualisation is great for saving money and resources, but if you lose a virtual server you have larger bigger problems than if you had just lost a single server. While no company wants to put their business at risk by under-protecting their VMs, nobody likes to spend more than they have to on non-productive expenditures like insurance. The Small Business Administration divides businesses into two categories: those who have experienced a disaster and those who are about to experience one, and a study by CIO.com revealed that it costs 42% of companies $1,000 per hour of downtime, 26% of companies $10,000 per hour of downtime – with upper ranges at over $50,000 per hour.
For companies that are trying to figure out the best way to protect your virtual machines, here are a few things to consider:
First, in order to avoid killing a mosquito with a baseball bat, figure out your cost of downtime. These can help you (and the executives funding the bat) understand how much data and time you can afford to lose if your VMs are interrupted or if they fail all together. To figure out how much you have to lose, think about how much money the company would lose if all the transaction data and e-mails from the last 12 to 24 hours were lost, if there are compliance risks with not being able to produce data, and what it would cost to have employees recreate the last 12 to 24 hours of data.
Or, if you want to know exactly what an hour of downtime will cost you, you can use a simple formula to figure it out:
Cost Per Occurrence = (TO + TD) x (HR + LR)
TO = Length of Outage
TD = Time Delta (the length of time since your last backup)
HR = Hourly Rate of Personnel (monthly expense per department divided by the total number of work hours)
LR = Lost Revenue per Hour (applies if the department generates profit – a good rule is to look at profitability over three months and divide by the number of work hours)
Second, before deciding how to protect your data, it is important to consider what the data is being protected from.
Four reasons why companies often choose to protect their data are listed overleaf.
Loss of a single resource
In this scenario, a single important resource fails or is interrupted. For example, losing a virtual server that end users depend on for product ordering would cripple a business that depends on electronic procurement. Likewise, many businesses would be seriously affected by the loss of one of their primary e-mail servers. Planning for this case usually means providing both backup and availability for the virtual server.
Loss of user data files
This unfortunately common scenario involves the accidental or intentional loss of important data files. The most common solution is to restore the lost data from a backup, but this can involve going back to a previous snapshot of the server – often with data loss.
Planned outages for maintenance or migration
The goal of planned maintenance or migrations on virtual machines is usually to restore, repair or patch service. Migrations usually mean users won’t have access to applications and data on virtual machines while the migration is in progress and is tested. If you can tolerate downtime and your IT staff doesn’t mind putting in a night or weekend, the most basic migration software will do.
If you require availability and for users to remain online during a migration, more advanced software will allow you to perform migrations without interruptions.
Loss of an entire facility
In this scenario, entire facilities and all of their resources are unavailable as a result of natural disasters, extended power outages, failure of the facility’s environmental conditioning systems, fire, flood or any other disaster our outage that takes out power or a physical structures. In this situation, it’s best to resume operations at another site. The downtime you tolerate is based on if you require just backup or backup and availability.
Few companies can tolerate days of downtime so they feel good about having an availability and disaster recovery plan in place, but don’t feel so great about sorting through the options. The good news is that if you’ve done your downtime homework, it’s not so bad.
Option 1: Tape backup and recovery systems
Tape backup can provide for the long-term archival needs of virtual servers, it’s portable, fairly secure, and the cost per megabyte is low. Tape backup is right for you if you can tolerate a day or more of downtime while you rebuild a whole VM or a whole server, if you have staff that won’t forget to switch tapes, if you aren’t regulated, and if you don’t have a lot to lose in a day’s worth of data.
Option 2: Replication-based backup and recovery
Backup software installs on your production and backup virtual servers and replicate data anywhere from once-a-day to “snapshots” or point-in-time recovery to continuous, real-time options. If your production server fails, you’ve got a copy of your data (and sometimes applications) waiting on you. If you can make a home for your backup server outside of your zip code you’ll avoid building and local disasters. If you can get it out of your region you’re even better protected. When evaluating products, look for hardware-independent capabilities – that way if your production server is actually destroyed you can recover to a different make and model and won’t have to go looking for an exact copy of the old server. Software-based backup is a great option if you can tolerate a few hours of downtime, don’t want to constantly manage the tape backup process (or can’t, as in the case of branch offices) and can’t afford to lose too much data.
Option 3: Add availability
The granddaddy of these options is software-based backup and recovery that includes continuous access to data and applications on your virtual machines in any situation. It’s usually not much more expensive than simple backup and recovery software, but the right product provides a whole other level of comfort if you can’t afford to lose data or time. Most availability options don’t offer a whole lot of granularity, but there are some that offers immediate failover and recovery. A comprehensive product in this category offers everything backup and recovery software does, except if your virtual server melts down, the backup server steps in immediately with a current copy of your data and applications. With good quality software, the switch happens so seamlessly that your end users won’t notice anything’s gone wonky in the server room.
Option 4: The cloud
The newest, and maybe coolest, kid on the block is backup and recovery in the cloud. Simply by installing cloud software on your VMs and renting a chunk of space from a cloud provider, you can have a virtual datacentre for a fraction of the cost of a physical datacentre. If you’re choosing cloud recovery, it’s probably a good idea to pick a software / storage combo that allows you to recover, or start up applications and data, from the cloud.
If you’re running VMs your eggs are all in one basket, so you’ve got to have a backup and recovery plan. Once you figure out how much downtime you can tolerate, you can set a realistic budget and pick a method for putting that plan in place.
