Choosing a Tape Drive

Tape drives remain the leading technology used bysizes and locations of the files on disk and is generally
organizations for backup and archiving. However, theunpredictable, but can be determined by the use of
plethora of tape drives on the market can makespecialised software.Secondly, if data is being
choosing the appropriate tape drive a confusing task.transferred over a network of computers to a
How do you select a tape drive that satisfies yourbackup server, the network may be incapable of
needs without blowing the budget? The following aresupplying data at a sufficient rate. The maximum
just some of the main factors to consider.1.throughput
CapacitySelect a tape drive that has sufficientof a network is predictable and easy to measure,
capacity to store your backups. Tape drives are ablebased on previous network performance.Consider a
to compress data so that more data may fit on thenetwork using 10BaseT Ethernet. This transfer rate
tape, which is why manufacturers specify both athrough this type of network cannot exceed 10MB/s,
native capacity and a compressed capacity, usuallyso it is immediately apparent that a tape drive
with a compression ratio at 2:1. However,requiring 20MB/s is
highly-compressed files such as those in video andinappropriate.3. Reliability and duty cycleA simple way
sound formats are hardly compressible at all. For thisto gauge the reliability of a tape drive is to find out
reason, do not heed the specified compressedthe Mean Time Between Failure (MTBF) as specified
capacity when choosing a tape drive.A good way toby the manufacturer. You should note, however, that
determine the size of the backup job afterthe MTBF is
compression is to study logs of past backups. Ifusually specified at a certain duty cycle. For example,
these are unavailable, it is safe to assume that theconsider a Travan tape drive with a MTBF of
data can be compressed at a ratio of 1.4:1, unless the370,000 hours at 20% duty cycle. The drive will only
hard drive contains an usually large number ofhave an average of 370,000 hours between failures
highly-compressed files.2. Transfer rateThe transferif it is run less than 20% of the time (about 4.8 hours
rate of the tape drive is becomes important whenper day), and running the tape drive for any longer
there is limited "window of opportunity" in whichwill significantly reduce the reliability of the drive.4.
backup jobs may run. It is often desirable forPriceThere is no point purchasing the highest-range
backups to take place during the night when networktape drive if it's simply too expensive. Consider how
use is at its lowest.Select a tape drive that is capablemuch value-for-money the tape drive will give you.
of completing a backup job within your window ofAre you willing to pay more
opportunity. For instance, to back up 400GB perfor extra performance? Or do you need to sacrifice
night, you will require a transfer rate of about 30GBsome performance to save on costs?If you choose
hour.A little known fact about tape drives is that datawisely, you should end up with a tape drive that
must be supplied to them at a sufficient rate in orderfulfils your organization's tape backup and archiving
to keep them streaming, or else the tape suffersneeds, without blowing the budget.Linus Chang is a
from start-stop motion.backup expert and the lead developer of
This motion severely degrades the life of the driveBackupAssist -- tape backup software that is simple
and tapes and the reliability of backups.There areand affordable, and perfect for small and medium
two usual reasons why tape drive are not bebusinesses. Protect your Windows servers, including
supplied with data at a sufficient rate. Firstly, the rateSQL Server and Exchange Server, to tape, REV
at which data is read from the hard disk of thedrive, hard drive, NAS and more, at a fraction of the
server is insufficient. This rate is dependent on thecost of other backup software.