Disk Based Backup Systems
Data is the most valuable asset of any organiza-
tion, hence it is very important to back it up on a
regular basis. Traditionally, backups were stored
in tape cartridges but over the past few years, we
have witnessed a change in this trend as disks
are used more and more to store backups. In this
article, we will discuss some of the advantages of
disk over tape as a backup medium.
The main advantage of disk backups over tapes is reducing the restore time. To restore from a tape,
it has to be first loaded into a tape drive and then forwarded to a specific point (linear medium)
before data can be read. Once the data is read, tape is rewound and ejected. Think of them as an
old VHS tapes used in VCRs. Conversely, disks do not need any loading time as they allow immedi-
ate access to data, significantly reducing recovery time.
Apart from performance, tapes are also quite fragile when compared with disks. They are prone
to environmental factors like dust, temperature and moisture. Excessive heat or moisture damag-
es the tape reel. Dust in tape drives or tape cartridges often cause mechanical faults. Faulty tape
drives can actually break the tape itself as well. Disks on the other hand are much more rigid and
resistant to these factors. Additionally, disk based backup systems have redundancy built-in,
meaning that even if one or two disks fail, it can simply be replaced without any loss of data.
Disk backups also make it very convenient to migrate backups to offsite locations. Backups are
simply copied over the network from one site to another. The entire process is automated and
no human intervention is required. Tape migration on the other hand is a manual process where
someone has to migrate the physical tapes from the primary site to the secondary site. Any human
error in this migration process can result in loss of data.
It is evident from the above arguments that disk based backup systems are superior to tape based
backup solutions. At UAE University, we use "EMC Data Domain", which is a disk based backup
storage appliance, for storing our backups. Backups are first stored on Data Domain at the Maqam
Campus site, and then replicated to the Data Domain at our Disaster Recovery site in Dubai,
ensuring the safety and security of university's data, even in case of a disaster at one of the sites.
By Mansoor Ahmad
15 |
December 2015
UITS Newsletter
