People are enamored with "cloud computing" these days. It's featured in TV commercials, vendor certifications, magazine articles, and industry analyst research. These hawkers commonly pitch "the cloud" as a magic solution for all your IT woes. However, let's examine why the cloud is not a replacement for traditional data backup.
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For example, assume our daily backup, or elephant, is 5 TB in size. How much bandwidth is necessary to push that backup into the cloud? How large must the straw be to fit the elephant? Here are some estimates to complete the data transfer within given time constraints.
| Size | Hours | Bandwidth | Similar Number of T1's |
|---|---|---|---|
| 5 TB | 24 | 509 Mbps | 315 |
| 5 TB | 10 | 1,222 Mbps | 755 |
| 5 TB | 5 | 2,444 Mbps | 1510 |
Coincidentally, moving 5 TB in 5 hours requires bandwidth roughly equivalent to an OC-48. Have you checked on the price of an OC-48 recently? I suggest you swallow your coffee and sit down before you look. It's far more costly than a brand new van and enough LTO 5 tapes to fill it. Keep in mind, we only need two or three tapes for our example.
Contrasting the cost of tape against the cost of equivalent bandwidth highlights why traditional data backup is not a candidate for the cloud. Organizations must fundamentally change the way they do backups to effectively leverage the cloud. Until then, replacing tape with the cloud is a pipe dream.
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