Disks are faster and better...
Disks and tapes are typically used for backup and archiving purposes. Disk backups are faster as their throughput is at least five-times over tapes. RAID protection schemes incorporated in disk subsystems makes them more reliable and better. The recovery is fastest using disks as a PiT copy within the disk subsystem and can be used for quick restore. With storage subsystems having FC and SATA available within the same box, managing data and cost of storage becomes more cost-effective.

Key parameters where disks score...
Backup window, recovery time objective (time taken to restore), recovery point objective (data lost at a recovery point), data reliability (over a period of time) and integrity, cost of managing data, and meeting service levels, are some of the key parameters where disks score better than tapes.

Good for highly critical applications...
Critical and high performance applications requiring maximum uptime should go in for disk-based solutions. Telcos, banks, manufacturers and even SMEs working under highly critical environment make good customers for disk-based systems. Such customers seek highest service level agreement (SLA) with 24x7 availability. High reliability and fast restore/backup is a critical for such business, which can be efficiently provided in a disk-based solution. Managing tape-based solutions can become a nightmare for all these customers.

Disk lowers total cost of ownership...
One time cost of disk will be marginally higher, but the total cost of ownership (TCO) could be lower as it involves lower management costs. More importantly disk-based solutions are better and faster for data retrieval. Solutions like snapshot make disk backups more efficient and faster.

Tapes are more popular for backups...
Tapes are still the most popularly deployed storage solution. Disks may never replace tapes, but will complement the tape technology.

True backups only on tape...
Backup means protecting and preserving data for days, months or even years. In tape, backup can be taken easily and copies of data can be made. For disaster recovery purpose it can be stored in the same or different locations. Data on tape is in a removable form and hence can be transported very easily. In disk, since DAT is overwritten many times, the copy of history of data is lost. Although RAID protections are given to disks, it does not give any protection against, database corruption, virus, sabotage, human errors and disasters.

Areas where tapes have an edge...
In tapes, we can have multiple drive libraries which gives us several Terabytes of storage space at very economical costs. For faster data backup and restoration libraries with multiple tape drives can be used to stream data simultaneously. These can be connected using fiber channel to give better throughput.

Where data is of highest importance...
Customers are at risk of losing business if data is lost. RAID does not protect data in many ways. Customer segments that have public data (like banks, financial institutions, insurance and telcos service providers) or customers who have consolidated data through the use of ERP or CRM applications; who need to preserve data for longer time due to governmental regulations or for their own reference (like software developer or call center) are some of the critical users of tape solutions.

Tapes are a lot cheaper than disk...
Tape-based solutions are very cost effective compared to disk based. Tapes are highly reliable and have shelf life of up to 30 years. Taking tape backup is very simple and changing the media is also very simple. Automated solutions are also available to do the job of changing the media.

Tapes find a place in every organization...
Tapes are popular in all organizations whether big or small. Disk-based storage like NAS or SAN is rarely found in SME. For data backup disk can never replace tape.

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