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How to design a backup strategy

For every business, there will come a time when critical files are lost, damaged or deleted, sometimes by accident and sometimes intentionally as in the case of a fire or theft or a security breach (think disgruntled employees or and ex-employee with an axe to grind). Having a sound backup strategy will assure continuity of business and the peace of mind that comes with having a backup of all the files and databases you need when they are needed.

One of the most common mistakes businesses, as well as individuals make is putting a backup system (e.g. tape or removable drives) in place and never testing to see if what is being backed up can be readily and reliably restored. Much like your insurance policy or the spare battery in your smoke alarm, if you don’t test the validity of your backup, by the time you find out you need it, it would be too late. In this article we will discuss some of the common techniques and best practices used by businesses today.

Backup Medium

  • Tape – Although an aging technology which has changed little in the past three decades, backup to tape media is still the most common form used today. Tape has the advantage of long shelf life (2 – 4 yrs.), low cost and simple operation. Vendors such as IBM and Dell make tape solutions capable of backing up up to 1TB or more per tape and practically limitless size for tape libraries. Two of the major disadvantages of using tape are a) high cost of tape drives and tape libraries and b) Slow backup and restore times.
  • Disk – Backing up to a disk or more likely a disk array, has become very popular in recent years, primarily because of the declining price of disk drives and the speed of backups and restores.
  • Removable Media – Many small business use removable disk drives such as iOmega to back up their critical files. the major shortcoming of the method is the limited space typically offered by such media and the fact that it is a manual process and requires discipline to do it consistently.
  • On-Line – Many business and individuals are turning to on-line backup services such as Mozy and HP. The greatest advantage of this method is physical separation (discussed below). However to be done properly and reliably, at a minimum you need to have T-1 connection speeds and the backup needs to carefully configured to not overwhelm the bandwidth (which it shares will all the users). Most on-line backup service providers charge on a per-Gigabyte basis. In other words, the more data you have to back up the more you pay. In recent years Amazon and iDrive have come up with relatively low cost or free solutions, however these services are primarily targeted to individual users, not businesses, as they are either limited in the size of backup allowed, or are not compatible to be run on servers where business data usually resides.

Rotation Strategies

  • Grand Father, Father, Son – This is the most common strategy used to rotate tapes or “hives”. In this strategy you label tapes for daily, weekly and monthly rotation and as you go though one set of daily tapes (sons), you graduate the last tape to the weekly (father) status and so forth. Some users make a single full backup, e.g. on Mondays and incremental or differential backup on subsequent days. That is not a wise strategy because if something were to have to your full backup tape, you would have no way of recovering most of your files. Tip: Use disk-based backups for daily runs and use tape for end of week.
  • Daily Rotation – In this method five or more tapes are used, one for each day of the week and rotated each week. This not a cost-effective or efficient method
  • Continuous Backup – First introduced by Veritas Backup Exec, continuous backup is exactly what is sounds like. In other words, the software monitors files and other data on the servers and whenever it sees a change, it backs it up and creates “snapshot” of the file at that point in time. So let’s say you are working on a spreadsheet and you save it ten times during the day as you modify it. With continuous backup, you could conceivable go back to each of the ten versions and recover that specific version when and if you need it.

Physical Security

Many businesses host or house their critical servers and backup system at a data center. This is a prudent strategy as most data centers have a array of redundancies such as uninterruptible power supplies (UPS), structural and access security and redundant internet connections. However just because your servers are in a secure location doesn’t mean you can neglect the other aspects of a backup strategy. After all if you had an un-authorized access to your servers and some data was lost or corrupted, the physical security of the data center will be of little help. Furthermore, living in an earthquake prone state here in California, it is not inconceivable that even a mild earthquake might render your server and your backups inaccessible, at least temporarily. So having a robust rotation strategy and “pulling” tapes is still necessary even if your server are safe. The idea of pulling tapes is to create a physical separation between where your data resides and there the backup tapes or disks are stored.

Another factor to consider is this. Let’s say you have been pulling and saving your tapes religiously and all of a sudden your servers were lost in a fire. Even if you have the backup tapes, do you have the tape drives and the software to recover the data on those tapes? The answer is simple. You need to have a method to quickly recover your data. This could be as simple as having a spare tape drive at home or an online “life-line”. Keep in mind that most online backup services do not guarantee how quickly you can access and restore your files, especially if you have a large volume of files or databases. For example in the case of, your request to burn a 20GB database to or a DVD or tape and send it to you will take several days.

Business Objective

In almost any type of business today, the goal of continuity of business relies on the availability and quick recovery in case of a disaster, of the critical files and databases needed to run the business. This includes your MS Office files, your emails, your SQL databases that might store everything from your customer data to you accounting system. Backing up of data is, or should be, only part of the overall disaster recovery plan. Most businesses who are genuinely committed to this principle have at least two backup methodologies. For example, the primary backup may be done to a disk array on a continuous or nightly basis and second on-line backup provides a “life-line” in case something were to happen to the servers and data storage arrays. To further safeguard the process, a tape (or whatever medium is used) is pulled and stored off-site at least once a week. The idea is to never have less backup sources than you can afford to lose. If you can afford to lose up to one week of files and updates without it affecting your business, then pulling one tape a week will probably be adequate. If you have a 24×7 business and your customers rely on your web and database server to be up all the time, then you probably need to implement a more robust disaster recovery plan.

Posted in Backup, Data Recovery, Desktop Security.

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  1. backup strategy - linked to this post on 01/28/2010

    […] and fail due to a faulty hard drive, simply because they did not backup regularly or at all onto …How to design a backup strategy | Tech ArticlesHaving a sound backup strategy will assure continuity of business and the peace of mind that comes […]

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