Is Tape Dead? A Review of Backup Technology
Original Article Date: 2007-06-26
In this issue, I'd
like to briefly talk about one of those trends that has been
spearheaded by the consumer, instead the usual push from major electronics vendors,
and that's the changing face of data backup.
Why Tape Has Historically Dominated Backup
Talk to any systems administrator over the last 20 years about backup of valuable
data, and you'll hear one key word, tape. Evolving over many
years, tape has been the standard method for providing essential backup of local
and network-based storage. Its purpose has been protecting data against disasters
such as fire, theft and hard disk failure, or user-based errors such as overwriting
or deleting needed files.
Tape filled this role principally because a unit of storage (KB/MB/GB) on tape used
to be significantly cheaper than the equivalent amount of storage
on a hard disk. Tape drives have never been particularly cheap, but the combined
cost of a drive and a set of backup tapes would be much less than the same
number of equivalent capacity hard drives.
A further factor in tape's dominance was the relative stability and durability of
the medium, especially when compared with IDE/ATA disks that typically did not inspire
confidence among IT staff if they were to consider backing up valuable data to them.
In recent years, however, ATA disks (in the guise of the current Serial ATA standard),
have improved in terms of reliability, whilst at the same time, plummetting
in cost per GB. The price advantage of a tape drive and set of backup tapes versus
the equivalent number of hard drives as backup has not only been reduced, but has
actually disappeared altogether. As I will demonstrate later, it is now significantly
cheaper to backup your data to a revolving system of removeable hard drives than
to use a conventional tape drive and tape-set system.
Alternatives to Tape for Backup - Old and New
Tape hasn't been the only means of protecting your data against loss. In the last
two decades, a number of alternatives to tape have come and gone:
- Floppy Drives - Once the standard for PC backup, their
tiny 1.44MB capacity
has become largely useless for modern file systems.
The Iomega ZIP drive proved to
be a popular enhancement to the floppy format, but now even these drives have been
made largely obsolete for personal backup by CD/DVD writeable media.
- Optical Media - In one form or another, removeable optical media
has been around as a method for backup
since the mid 1980s, from the original WORM
drives, various formats of Magneto-Optical (MO) cartridges, and most recently writeable
CDs and DVDs. For non-networked, PC file backup, rewriteable CDs/DVDs
are the most popular choice, owing to the very low cost of both media and drives,
and relatively simple backup and restore operations. For comprehensive and structured
corporate backup systems, however, the relatively limited capacity
of CDs/DVDs (currently
9GB for Dual-Layer DVD) does not make them suitable. Furthermore, the future of
optical media is unlikely to change this, as it seems optical technology is unable
to keep pace with the growth in storage used by corporate computing (e.g. Blu-ray
disks are at most 50GB, still smaller than the smallest mainstream hard disk at
80GB).
- Internet - A relatively recent trend, off-site storage via internet
broadband connection has emerged as a means for individuals and small businesses
to easily protect their data from worst-case site based scenarios such as fire,
flood and theft. In these situations, it is possible that the backup store could
be destroyed along with the original store, thus invalidating any local backup strategy.
By using online drive services such as Xdrive and iBackup, one can purchase
5GB or more of a drive somewhere away from your home or office, and backup your
valued data onto it, thus insuring against local catastrophes.
Downsides, however, can be
slow transfer times, and concern about some unscrupulous employee of the drive service
decrypting and looking at your sensitive files.
- Network Drive Storage - Grouping together on-line or near-line
hard-disk storage in this category, network drive storage is popular amongst medium
to large corporate IT departments because of its high availability and speed. A
recent trend spearheaded by Buffalo has
also brought this concept to many homes
and small businesses, through their mini-NAS solutions. An explosive growth in single
USB external hard drives has also meant that many home users are now backing up
their data to these drives instead of DVD. The downside to these, however,
is that they can be expensive, and are as equally vulnerable to fire, flood and
theft as your original store, so they only really protect you from disk failure
or user-error.
- Removeable Hard Drives - An increasingly popular trend amongst
small to medium sized businesses, this method of effectively substituting tapes
with hard drives bolted to hotswap drive carriers. With massive capacity, portability
and low cost driving this solution, removeable hard drives could be the Tape
Killer many have predicted. As I'll reveal below, building a backup
infrastructure using removeable hard drives in place of tape is now the cheaper
option.
Are Removeable Hard Drives set to become the Tape Killer?
Removeable Hard Drives are a substitute for Tape Backup. I was alerted to this trend
by a number of my customers who had begun improvising in this area.
Like in a tape backup system,
you would do nightly backups onto 5-7 different hard drives which can be loaded
into and out of a hotswap hard drive enclosure mounted in a standard 5.25" drive
bay (see typical photo opposite). At the end of each week, you would then take one
of the drives out of the daily rotation of drives to keep as a weekly snapshot,
and the same again at the end of each month.
So a removeable hard drive backup system would typically require between 7 and 10
drives, depending on how many days a week you perform a backup, and over what intervals
you set aside additional backups. Each of these drives would require a mounting
frame into which it would be securely inserted, but the system would require only
one hotswap bay, mounted in one of the server or workstation's 5.25" drive bays.
Just like in tape, you would store the removeable drives in a secure location, such
as a safe, or off-site, such as the system administrator's home office.
But how do the costs and other aspects of removeable hard drives compare with tape?
Consider this scenario. A small business has a server running a website, MS Exchange,
network file storage and a contacts database. Their typical storage usage does not
exceed 200GB. The data stored on the serve is invaluable, the loss of which could
result in serious hardship for the business.
So they need a backup strategy.
Traditionally, the only viable option for secure, rapid and relatively inexpensive
backup that can match their requirements was tape. But let's now consider removeable
hard drives as a rival option. Here is the outlay needed for both tape and removeable
hard drive systems that would fit their needs:
TAPE
1 x Sony SDX-570V AIT-2 Tape Drive (80GB native, 208GB compressed) - $948.00
7 x AIT-2 Tapes (5 daily, 1 weekly, 1 monthly) - $300.00
Total cost: $1,248.00
REMOVEABLE HDD
1 x 2/4 port SATA disk controller that supports hotswap - $200.00
8 x WD2500KS 250GB 7,200rpm SATA HDD (5 daily, 1 weekly, 1 monthly, 1 spare) - $640.00
7 x 5.25" Hotswap caddy and enclosures for HDDs (only one enclosure used) - $210.00.
Total cost: $1,050.00
So on cost grounds, one can see that a system of removeable hard disks in place
of tape is the cheaper option. Hard Drives do have the disadvantage
of being somewhat more fragile than tapes - you can't throw them
around or drop them on the floor like tapes, for instance. But on the plus side, hard drives allow rapid random access
to their contents for file recovery, whereas tapes are notorious for being
a serial medium, requiring often lengthy rewinds and fast-forwards
when retrieving data.
With the downward trend in hard drive storage pricing continuing at a faster pace
than any corresponding drops in tape backup pricing, the cost advantages to removeable
hard drive storage are set to increase. Additionally, the trend in squeezing more
and more data onto the same area of a hard disk-platter continues at a much more
rapid pace than that of tape.
And for these
two reasons above any other, I believe
that removeable hard drives will continue to grow as means of corporate data backup,
and will ultimately become the tape killer.
Ben Ranson
Chief Systems Engineer
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