Quantum DLT 2000 Handbook page 96

protective spot for a period of time. Some companies, especially
those required by law to maintain historical records such as insur-
ance companies and banks, archive data to special vaults or storage
sites specially designed to protect valuable records.
File-by-file vs. Image Backups
There are two basic forms of backup: file-by-file and image back-
up. File-by-file backups take much longer than image backups,
because the backup system must request each file from the operat-
ing system. File-by-file backups rarely achieve maximum tape drive
performance because the tape stops and starts frequently, prevent-
ing optimal streaming. System performance can usually be
improved by performing regular disk de-fragmentation.
Fragmented files and disks can take much longer to back up.
Image backups are like a snapshot of your disk at a moment in
time. Because data is sent to the tape in large, virtually seamless
chunks, the tape drive is typically able to achieve optimal stream-
ing and maximum performance. Image backups are important for
data restoration following a disaster or other catastrophic data loss,
when you want to restore everything on your system. Most image-
based backup systems also allow individual file restoration as well.
Real-time backup, a variation on file-by-file backups, is available
with some data management software packages. These new soft-
ware packages log changes to your data in real-time as they occur
on your network or file servers. This type of solution is a cost-
effective way to provide up-to-the-minute accuracy in data backup.
Real-time backup is increasing in popularity among 7x24 hour
operations where the backup window has been slammed shut.
The penalty for this type of system is degradation in server and net-
work performance. However, as with any backup solution, the value
QUANTUM DLTtape HANDBOOK 9.3