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Backup and Recovery Basics

Implementing a comprehensive data protection strategy

No matter how large or small your business is, data backup and recovery needs to be a vital part of your IT planning. From basic tape backup to complex multiserver SAN environments, many technologies and techniques are available to meet the needs of corporate data-protection administrators. However, the core concepts and best practices of data backup and recovery apply to every computing environment.

One important first principle is that a backup and recovery plan is not a replacement for a disaster recovery plan. A backup and recovery plan defines a business's data backup and recovery needs and specifies the workflow that meets those needs. A disaster recovery plan defines how the business will get back up and running after any kind of catastrophic event. Data backup and recovery is part of a disaster recovery plan—not a substitute for one. (To walk through the steps of creating a disaster recovery plan for your business, see Ben Smith, “Surviving the Worst,” June 2005, InstantDoc ID 46289.)

Let's look at the fundamentals of building a backup and recovery plan for your organization. Then, I'll take you on a quick tour of the most popular backup and recovery hardware.

Start with a Plan
Typically, the first step in backup and recovery is creating a backup and recovery plan. However, for most businesses, the actual first step is determining what funding is available for implementing data protection. It does little good to create a detailed plan that you can't afford to implement. If funding for backup and recovery isn't a problem for your business, than you're already at step two—creating the plan.

Regardless of how simple your backup and recovery needs are, a written plan is a necessity. In any business larger than a sole proprietorship, the possibility exists that the person who knows how to back up data or recover lost files won't be available when he or she is needed. (In an enterprise-class business, that's not a possibility—it's a guarantee.) A detailed written plan that describes how data is backed up and recovered guarantees that you'll be able to recover data when you need do, regardless of your IT staffing circumstances.

Two Plans in One
I've been referring to “a” plan, but in reality, your data-protection strategy should comprise two separate plans—one for data backup and another for recovery. Depending upon how complex your business is, the plans might be simple sets of instructions that describe how to back up and restore data in one location and from one or two applications, or they might include multiple sets of conditional instructions for backing up specific data in certain locations, from certain applications. Both plans in your data-protection strategy will depend to a certain extent on the software and hardware you've chosen to meet your business's backup and recovery needs. “Designing a Backup and Recovery Strategy,” on page 49, outlines the steps to building a data protection plan for your organization.

The backup plan. Your backup plan needs to include a mechanism for ensuring that each backup will be initiated and completed. Similarly, the plan should identify a process for confirming that backups are capable of being restored. All plans should include a process for backing up new systems so that they can be quickly restored to a baseline configuration. The entire backup plan should be available as a complete set of instructions that provides the hands-on guide to your backup process.

The recovery plan. Recovery plans are necessarily more complex than backup plans. All recovery plans need to describe common recovery operations: for example, how to restore a single file, how to restore a directory, how to restore an entire computer. In more complex environments, recovery plans should specify system dependencies and the order in which systems are to be restored. Bringing up restored computers in the wrong order will keep applications from running correctly.

A common question about data recovery is whether end users should be responsible for their own backups. Typically, giving users backup responsibility isn't a good idea (beyond configuring your network backup to protect a user's home directories). However, many backup and restore applications give administrators the ability to configure the system to give end users limited recovery capabilities. Generally, user-restore capabilities are confined to individual files or user directories; IT still maintains the responsibility for more complex restoration tasks (and documenting these tasks needs to be part of the recovery plan). Restore capabilities won't necessarily be provided to all users, so you need to document the policies and procedures for users to whom you don't give the ability to self-restore.

Backup and Recovery Hardware
Traditionally, the basic backup hardware is tape. Simple, effective, and inexpensive, tape is still a viable option as the primary backup solution for many companies. The speed at which data is written to tape is the limiting factor in tape's effectiveness; although tape drives continue to become faster, they remain the choke point for data backup. Only so much time is available for live data to be copied to tape before other demands on the data or the network make the backup process untenable. In a business operating 24 × 7, the window is usually exceedingly small, and that bottleneck can become a significant problem. But even in situations where tape isn't the optimal choice for live backup, it remains the medium of choice for offline backups.

Gauging Capacity
Keep in mind that the amount of backup storage you need doesn't have to equal the total amount of storage on your network—it needs only to accommodate the amount of data within that total that changes. For example, your business might have half a terabyte of storage in use on its network, but the majority of that data is likely static, with perhaps less than 5 percent changing on a daily basis. In that case, your backup solution needs to be able to regularly accommodate not 500GB but only 25GB, a capacity well within the range of every enterprise backup solution.

Although backing up a 500GB data set to tape is inexpensive, restoring a single file or directory from somewhere within the twenty or more backup tapes containing that 500GB of data can be difficult. Usually, the file or directory to be restored will have been recently modified, which means it will be found in one of the tapes in active rotation, not in offsite archives. This situation reduces the time IT must spend to find the data to be restored, but it doesn't eliminate the necessity of using IT resources.

Alternatives to Tape
Current backup technologies are moving in the direction of disk-to-disk online backup—a faster, more reliable, and more secure medium than tape. In this environment, data is copied from its primary storage location to an online hard disk system. Data can be transferred across the network or over a dedicated storage medium such as a SAN, depending on the corporate need and computing environment. You can move the data on the secondary hard disk storage to offline archival storage or, if capacity is large enough, leave it on the secondary storage. Most organizations will undoubtedly move data to tape to allow for off-site storage of data as part of their disaster recovery plan. Disk-to-disk online backup solutions are more expensive than tape-only solutions, but entry-level prices are reasonable enough that even small businesses can consider these solutions as part of their backup strategy.

If you choose a disk-to-disk solution as your primary backup mechanism, you'll need to take into account the additional strain the solution will place on your network backbone. Although it's unlikely that you'll seriously tax a 100Base-T or Gigabit Ethernet network while writing to a tape device, using disk-to-disk backup means that you can be writing data acquired from multiple sources at speeds that can exceed the available bandwidth on your network. In this case, you need to be careful in architecting your network. Dedicated network connections between servers and backup devices might be required to get the most from disk-to-disk backup tools.

For small businesses, businesses with lots of mobile or remote users, or businesses with many distributed locations, a nontraditional backup methodology worth consideration is the Internet-based backup service. Internet-based backup service providers install a small piece of client software on the target computer (which is any server or client you choose). You then determine what level of backup you require (e.g., file-level backup, folder-level backup, machine-level backup) and configure the client software for the appropriate level of protection. Once the protection is enabled, you can perform a restore directly from a Web browser console. You can grant users whose machines are protected the ability to perform restores in the same way.

The most significant downside associated with Internet-based backup technology is the lack of Internet bandwidth available to many remote or distributed sites. Many businesses opt for cost-effective business cable modem or DSL service and forget about the asymmetric aspect of the connection; they might be getting 6MB download speeds, but the upload speed is well under 1MB. Consequently, if users of the backup service elect to protect entire computers, they will be attempting to push a huge amount of data through a very small upstream pipe. To get the most out of Internet-based backup, initial configurations need to be staggered and backups scheduled to take place when there is no other use of the Internet connection for an extended period of time.

Although it's less of a problem, restoring large amounts of data over the Internet can present difficulties. A definite limit exists to the amount of data you can pull down from the backup service servers. Consequently, many service providers offer delivery of complete backups on DVD or tape, which can be a viable option if you don't need the backed-up data immediately.

Data Recovery Integration
Backup and recovery processes need to be integral parts of the IT work flow. Starting with a basic needs analysis and delivering a backup solution that accommodates the amount of data that must be protected and provides for workable restoration processes, IT administrators need to develop a set of practices and procedures that create and maintain a reliable, secure data protection environment. Setting standards for backup and recovery and abiding by these documented guidelines can prevent many of the problems with data recovery that administrators too often discover when there is no time to find solutions.

TAGS: Security
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