Lowe D. Networking For Dummies
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Book III
Chapter 9
Backing Up
Your Data
267
How Many Sets of Backups Should You Keep?
✦ To improve network backup speed and to minimize the effect that net-
work backups have on the rest of the network, consider using a 1,000
Mbps switch instead of a normal 100 Mbps switch to connect the serv-
ers and the backup client. That way, network traffic between the server
and the backup client won’t bog down the rest of the network.
✦ Any files that are open while the backups are running won’t get backed
up. That’s usually not a problem because backups are run at off hours
when people have gone home. However, if someone leaves his computer
on with a Word document open, that Word document won’t be backed up.
One way to solve this problem is to set up the server so that it automati-
cally logs everyone off the network before the backups begin.
✦ Some backup programs have special features that enable them to back
up open files. For example, the Windows Server 2003 and 2008 backup
programs do this by creating a snapshot of the volume when it begins,
thus making temporary copies of any files that are modified during the
backup. The backup backs up the temporary copies rather than the ver-
sions being modified. When the backup finishes, the temporary copies
are deleted.
How Many Sets of Backups Should You Keep?
Don’t try to cut costs by purchasing one backup tape and reusing it every
day. What happens if you accidentally delete an important file on Tuesday
and don’t discover your mistake until Thursday? Because the file didn’t exist
on Wednesday, it won’t be on Wednesday’s backup tape. If you have only
one tape that’s reused every day, you’re outta luck.
The safest scheme is to use a new backup tape every day and keep all your
old tapes in a vault. Pretty soon, though, your tape vault can start looking
like the warehouse where they stored the Ark of the Covenant at the end of
Raiders of the Lost Ark.
As a compromise between these two extremes, most users purchase several
tapes and rotate them. That way, you always have several backup tapes to fall
back on, just in case the file you need isn’t on the most recent backup tape.
This technique is tape rotation, and several variations are commonly used:
✦ The simplest approach is to purchase three tapes and label them A, B,
and C. You use the tapes on a daily basis in sequence: A the first day, B
the second day, C the third day; then A the fourth day, B the fifth day,
C the sixth day, and so on. On any given day, you have three genera-
tions of backups: today’s, yesterday’s, and the day-before-yesterday’s.
Computer geeks like to call these the grandfather, father, and son tapes.
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268
A Word about Tape Reliability
✦ Another simple approach is to purchase five tapes and use one each
day of the workweek.
✦ A variation of the preceding bullet is to buy eight tapes. Take four
of them and write Tuesday on one label, Wednesday on the second,
Thursday on the third, and Friday on the fourth label. On the other four
tapes, write Monday 1, Monday 2, Monday 3, and Monday 4. Now, tack up
a calendar on the wall near the computer and number all the Mondays in
the year: 1, 2, 3, 4, 1, 2, 3, 4, and so on.
On Tuesday through Friday, you use the appropriate daily backup tape.
When you run a full backup on Monday, consult the calendar to decide
which Monday tape to use. With this scheme, you always have four
weeks’ worth of Monday backup tapes, plus individual backup tapes for
the rest of the week.
✦ If bookkeeping data lives on the network, make a backup copy of all
your files (or at least all your accounting files) immediately before
closing the books each month; then retain those backups for each
month of the year. This doesn’t necessarily mean that you should pur-
chase 12 additional tapes. If you back up just your accounting files, you
can probably fit all 12 months on a single tape. Just make sure that you
back up with the “append to tape” option rather than the “erase tape”
option so that the previous contents of the tape aren’t destroyed. Also,
treat this accounting backup as completely separate from your normal
daily backup routine.
Keep at least one recent full backup at another location. That way, if your
office should fall victim to an errant Scud missile or a rogue asteroid, you
can re-create your data from the backup copy that you stored offsite. Make
sure the person entrusted with the task of taking the backups to this off-site
location is trustworthy.
A Word about Tape Reliability
From experience, I’ve found that although tape drives are very reliable, they
do run amok once in a while. The problem is that they don’t always tell you
when they’re not working. A tape drive (especially the less-expensive Travan
drives) can spin along for hours, pretending to back up your data — but in
reality, your data isn’t being written reliably to the tape. In other words, a
tape drive can trick you into thinking that your backups are working just
fine. Then, when disaster strikes and you need your backup tapes, you may
just discover that the tapes are worthless.
Don’t panic! Here’s a simple way to assure yourself that your tape drive is
working. Just activate the “compare after backup” feature of your backup
software. Then, as soon as your backup program finishes backing up your
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Book III
Chapter 9
Backing Up
Your Data
269
About Cleaning the Heads
data, it rewinds the tape, reads each backed-up file, and compares it with the
original version on the hard drive. If all files compare, you know your back-
ups are trustworthy.
Here are some additional thoughts about the reliability of tapes:
✦ The compare-after-backup feature doubles the time required to do a
backup, but that doesn’t matter if your entire backup fits on one tape.
You can just run the backup after hours. Whether the backup and repair
operation takes one hour or ten doesn’t matter, as long as it’s finished
by the time the network users arrive at work the next morning.
✦ If your backups require more than one tape, you may not want to run
the compare-after-backup feature every day. However, be sure to run it
periodically to check that your tape drive is working.
✦ If your backup program reports errors, throw away the tape and use a
new tape.
✦ Actually, you should ignore that last comment about waiting for your
backup program to report errors. You should discard tapes before your
backup program reports errors. Most experts recommend that you
should use a tape only about 20 times before discarding it. If you use the
same tape every day, replace it monthly. If you have tapes for each day
of the week, replace them twice yearly. If you have more tapes than that,
figure out a cycle that replaces tapes after about 20 uses.
About Cleaning the Heads
An important aspect of backup reliability is proper maintenance of your tape
drives. Every time you back up to tape, little bits and specks of the tape rub
off onto the read and write heads inside the tape drive. Eventually, the heads
become too dirty to reliably read or write data.
To counteract this problem, clean the tape heads regularly. The easiest way
to clean them is to use a cleaning cartridge for the tape drive. The drive
automatically recognizes when you insert a cleaning cartridge and then per-
forms a routine that wipes the cleaning tape back and forth over the heads
to clean them. When the cleaning routine is done, the tape is ejected. The
whole process takes only about 30 seconds.
Because the maintenance requirements of each drive differ, check the
drive’s user’s manual to find out how and how often to clean the drive. As a
general rule, clean the drives once weekly.
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270
Backup Security
The most annoying aspect of tape drive cleaning is that the cleaning car-
tridges have a limited life span. And, unfortunately, if you insert a used-up
cleaning cartridge, the drive accepts it and pretends to clean the drive. For
this reason, keep track of how many times you used the cleaning cartridge
and replace it as recommended by the manufacturer.
Backup Security
Backups create an often-overlooked security exposure for your network.
No matter how carefully you set up user accounts and enforce password
policies, if any user (including a guest) can perform a backup of the system,
that user may make an unauthorized backup. In addition, your backup tapes
themselves are vulnerable to theft. As a result, make sure that your backup
policies and procedures are secure by taking the following measures:
✦ Set up a user account for the user who does backups. Because this user
account has backup permission for the entire server, guard its password
carefully. Anyone who knows the username and password of the backup
account can log on and bypass any security restrictions that you place
on that user’s normal user ID.
✦ Counter potential security problems by restricting the backup user ID
to a certain client and a certain time of the day. If you’re really clever
(and paranoid), you can probably set up the backup user’s account so
that the only program it can run is the backup program.
✦ Use encryption to protect the contents of your backup tapes.
✦ Secure the backup tapes in a safe location, such as, um, a safe.
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Chapter 10: Disaster Recovery and
Business Continuity Planning
In This Chapter
✓ Realizing the need for backups
✓ Making a plan
✓ Practicing disaster recovery
✓ Remembering tape rotation and other details
O
n April Fools’ Day about 20 years ago, my colleagues and I discov-
ered that some loser had broken into the office the night before and
pounded our computer equipment to death with a crowbar. (I’m not making
this up.)
Sitting on a shelf right next to the mangled piles of what used to be a Wang
minicomputer system was an undisturbed disk pack that contained the only
complete backup of all the information that was on the destroyed computer.
The vandal didn’t realize that one more swing of the crowbar would have
escalated this major inconvenience into a complete catastrophe. Sure, we
were up a creek until we could get the computer replaced. And in those
days, you couldn’t just walk into your local Computer Depot and buy a new
computer off the shelf — this was a Wang minicomputer system that had
to be specially ordered. After we had the new computer, though, a simple
restore from the backup disk brought us right back to where we were on
March 31. Without that backup, getting back on track would have taken
months.
I’ve been paranoid about disaster planning ever since. Before then, I thought
that disaster planning meant doing good backups. That’s a part of it, but I
can never forget the day we came within one swing of the crowbar of losing
everything. Vandals are probably much smarter now: They know to smash
the backup disks as well as the computers themselves. Being prepared for
disasters entails much more than just doing regular backups.
Nowadays, the trendy term for disaster planning is a business continuity plan
(BCP). I suppose the term disaster planning sounded too negative, like we
were planning for disasters to happen. The new term refocuses attention on
the more positive aspect of preparing a plan that will enable a business to
carry on with as little interruption as possible in the event of a disaster.
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272
Assessing Different Types of Disasters
For more in-depth information about this topic, please refer to IT Disaster
Recovery Planning For Dummies by Peter Gregory.
Assessing Different Types of Disasters
Disasters come in many shapes and sizes. Some types of disasters are more
likely than others. For example, your building is more likely to be struck by
lightning than to be hit by a comet. In some cases, the likelihood of a particu-
lar type of disaster depends on where you’re located. For example, crippling
snowstorms are more likely in New York than in Florida.
In addition, the impact of each type of disaster varies from company to com-
pany. What may be a disaster for one company may only be a mere incon-
venience for another. For example, a law firm may tolerate a disruption in
telephone service for a day or two. Loss of communication via phone would
be a major inconvenience but not a disaster. To a telemarketing firm, how-
ever, a day or two with the phones down is a more severe problem because
the company’s revenue depends on the phones.
One of the first steps in developing a business continuity plan is to assess
the risk of the various types of disasters that may affect your organization.
Weigh the likelihood of a disaster happening with the severity of the impact
that the disaster would have. For example, a meteor crashing into your
building would probably be pretty severe, but the odds of that happening
are miniscule. On the other hand, the odds of your building being destroyed
by fire are much higher, and the consequences of a devastating fire would be
about the same as those from a meteor impact.
The following sections describe the most common types of risks that most
companies face. Notice throughout this discussion that although many of
these risks are related to computers and network technology, some are not.
The scope of business continuity planning is much larger than just computer
technology.
Environmental disasters
Environmental disasters are what most people think of first when they think
of disaster recovery. Some types of environmental disasters are regional.
Others can happen pretty much anywhere.
✦ Fire: Fire is probably the first disaster that most people think of when
they consider disaster planning. Fires can be caused by unsafe condi-
tions; carelessness, such as electrical wiring that isn’t up to code; natu-
ral causes, such as lightning strikes; or arson.
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Book III
Chapter 10
Disaster Recovery
and Business
Continuity Planning
273
Assessing Different Types of Disasters
✦ Earthquakes: Not only can earthquakes cause structural damage to your
building, but they can also disrupt the delivery of key services and utili-
ties, such as water and power. Serious earthquakes are rare and unpre-
dictable, but some areas experience them with more regularity than
others. If your business is located in an area known for earthquakes,
your BCP should consider how your company would deal with a devas-
tating earthquake.
✦ Weather: Weather disasters can cause major disruption to your busi-
ness. Moderate weather may close transportation systems so that your
employees can’t get to work. Severe weather may damage your building
or interrupt delivery of services, such as electricity and water.
✦ Water: Flooding can wreak havoc with electrical equipment, such as
computers. If floodwaters get into your computer room, chances are
good that the computer equipment will be totally destroyed. Flooding
can be caused not only by bad weather but also by burst pipes or mal-
functioning sprinklers.
✦ Lightning: Lightning storms can cause electrical damage to your com-
puter and other electronic equipment from lightning strikes as well as
surges in the local power supply.
Deliberate disasters
Some disasters are the result of deliberate actions by others. For example
✦ Intentional damage: Vandalism or arson may damage or destroy your
facilities or your computer systems. The vandalism or arson may be
targeted at you specifically, by a disgruntled employee or customer, or it
may be random. Either way, the effect is the same.
Don’t neglect the possibility of sabotage. A disgruntled employee who
gets hold of an administrator’s account and password can do all sorts of
nasty things to your network.
✦ Theft: Theft is always a possibility. You may come to work someday to
find that your servers or other computer equipment have been stolen.
✦ Terrorism: Terrorism used to be something that most Americans weren’t
concerned about, but September 11, 2001, changed all that. No matter
where you live in the world, the possibility of a terrorist attack is real.
Disruption of services
You may not realize just how much your business depends on the delivery
of services and utilities. A BCP should take into consideration how you will
deal with the loss of certain services:
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274
Assessing Different Types of Disasters
✦ No juice: Electrical power is crucial for computers and other types
of equipment. During a power failure once (I live in California, so I’m
used to it), I discovered that I can’t even work with pencil and paper
because all my pencil sharpeners are electric. Electrical outages are
not uncommon, but the technology to deal with them is readily avail-
able. UPS (uninterruptible power supply) equipment is reliable and
inexpensive.
✦ No communications: Communication connections can be disrupted
by many causes. A few years ago, a railroad overpass was constructed
across the street from my office. One day, a backhoe cut through the
phone lines, completely cutting off our phone service — including our
Internet connection — for a day and a half.
✦ No water: An interruption in the water supply may not shut down your
computers, but it can disrupt your business by forcing you to close your
facility until the water supply is reestablished.
Equipment failure
Modern companies depend on many different types of equipment for their
daily operations. The failure of any of these key systems can disrupt busi-
ness until the systems are repaired:
✦ Computer equipment failure can obviously affect business operations.
✦ Air-conditioning systems are crucial to regulate temperatures, espe-
cially in computer rooms. Computer equipment can be damaged if the
temperature climbs too high.
✦ Elevators, automatic doors, and other equipment may also be neces-
sary for your business.
Other disasters
You should assess many other potential disasters. Here are just a few:
✦ Labor disputes
✦ Loss of key staff because of resignation, injury, sickness, or death
✦ Workplace violence
✦ Public health issues, such as epidemics, mold infestations, and so on
✦ Loss of a key supplier
✦ Nearby disaster, such as a fire or police action across the street that
results in your business being temporarily blocked off
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Book III
Chapter 10
Disaster Recovery
and Business
Continuity Planning
275
Analyzing the Impact of a Disaster
Analyzing the Impact of a Disaster
With a good understanding of the types of disasters that can affect your
business, you can turn your attention to the impact that these disasters can
have on your business. The first step is to identify the key business pro-
cesses that can be impacted by different types of disasters. These business
processes are different for each company. For example, here are a few of the
key business processes for a publishing company:
✦ Editorial processes, such as managing projects through the process of
technical editing, copyediting, and production
✦ Acquisition processes, such as determining product development strat-
egies, recruiting authors, and signing projects
✦ Human resource processes, such as payroll, hiring, employee review,
and recruiting
✦ Marketing processes, including sales tracking, developing marketing
materials, sponsoring sales conferences, exhibiting at trade events, and
so on
✦ Sales and billing processes, such as filling customer orders, maintaining
the company Web site, managing inventory, and handling payments
✦ Executive and financial processes, such as managing cash flow, secur-
ing credit, raising capital, deciding when to go public, and deciding
when to buy a smaller publisher or sell out to a bigger publisher
The impact of a disruption to each of these processes will vary. One
common way to assess the impact of business process loss is to rate the
impact of various degrees of loss for each process. For example, you may
rate the loss of each process for the following time frames:
✦ 0 to 2 hours
✦ 2 to 24 hours
✦ 1 to 2 days
✦ 2 days to 1 week
✦ More than 1 week
For some business processes, an interruption of two hours or even one day
may be minor. For other processes, even the loss of a few hours may be very
costly.
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276
Developing a Business Continuity Plan
Developing a Business Continuity Plan
A BCP is simply a plan for how you will continue operation of your key busi-
ness processes should the normal operation of the process fail. For example,
if your primary office location is shut down for a week because of a major
fire across the street, you won’t have to suspend operations if you have a
business continuity plan in place.
The key to a BCP is redundancy of each component that is essential to your
business processes. These components include:
✦ Facilities: If your company already has multiple office locations, you
may be able to temporarily squeeze into one of the other locations for
the duration of the disaster. If not, you should secure arrangements in
advance with a real estate broker so that you can quickly arrange an
alternate location. By having an arrangement made in advance, you can
move into an emergency location on a moment’s notice.
✦ Computer equipment: It doesn’t hurt to have a set of spare computers
in storage somewhere so that you can dig them out to use in an emer-
gency. Preferably, these computers would already have your critical
software installed. The next best thing would be to have detailed plans
available so that your IT staff can quickly install key software on new
equipment to get your business up and running.
Always keep a current set of backup tapes at an alternate location.
✦ Phones: Discuss emergency phone services in advance with your
phone company. If you’re forced to move to another location on
24-hour notice, how quickly can you get your phones up and running?
And can you arrange to have your incoming toll-free calls forwarded to
the new location?
✦ Staff: Unless you work for a government agency, you probably don’t
have redundant employees. However, you can make arrangements in
advance with a temp agency to provide clerical and administrative help
on short notice.
✦ Stationery: This sounds like a small detail, but you should store a
supply of all your key stationery products (letterhead, envelopes,
invoices, statements, and so on) in a safe location. That way, if your
main location is suddenly unavailable, you don’t have to wait a week to
get new letterhead or invoices printed.
✦ Hard copy files: Keep a backup copy of important printed material (cus-
tomer billing files, sales records, and so on) at an alternate location.
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