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.
End of Article
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