Search "backing up cloud-based resources" and you'll see numbers of articles on how to back up your local machines to the cloud, but there is virtually nothing about how to back up the data already stored in the cloud. Does this concern you? It should!
Data loss incidents vs Loss of data access incidents
Just to make sure you're sufficiently concerned, let's revisit some of the more well-known "disappearances" of cloud-based data in recent years. In 2009, T-Mobile Sidekick users lost all data stored "in the cloud." It's believed that this data loss was attributable to human error. Ironically, they failed to back up the data before performing a hardware upgrade. What's more? In 2008, the Linkup lost access to unspecified amounts of customer data for 20,000 paying subscribers which ended up closing its doors forever. A similar incident also happened in 2007, where Carbonite lost backup data for over 7,500 customers.
That's it? No. Even when your data is stored somewhere it might not be at your disposal 24/7 because there is a risk called "Loss of Data Access", which means that there is a copy of the data somewhere but it will take time to make it usable. No one knows how long it will take until the data is restored or recovered and during that time it may seem like the data was lost. In September and July this year, Gmail and related services were offline for 40 minutes; similar outages also occurred in April and December last year. The list goes on that Netflix services were offline due to an operational dysfunction at Amazon Web Services last year, and in 2011, Amazon EC2 suffered an outage as a result of a network configuration change run amok…
2 key lessons
There are two lessons to be learned from these incidents.
1. Never put all your eggs in one basket.
2. While cloud-based services/storage may be cheaper and more convenient, they are not necessarily any less risk-prone than on-premise solutions. It's still servers, disk drives, software, and people -- all of which can malfunction or fail at almost any time.
Plan for protecting cloud-based data
Backups are still a necessary component of a disaster recovery plan. The question is: Where do you back up your cloud-based services/storage? The answer: A different cloud-based provider!
The value of using an alternate cloud-based storage provider for backups is because there is NO guarantee that the location in which you currently store your data will be online tomorrow, or stay online long enough for you to get your data transferred. The prime example of this is the recent announcement of the Nirvanix closure. Despite the company giving its customers two weeks to move their data elsewhere, it will take them days to transfer their data given the majority of the available bandwidth, let alone the number of days for them to get their data off that service when the bandwidth is shared with every other customer within a fixed period of time. Therefore, it is much better to already have the data elsewhere, and not actually have to dump it all.
So what factors do you need to consider when selecting a second cloud-based provider? Generally they should be similar to the factors considered when selecting your primary cloud provider, but this also relates to how the secondary data is being stored. If it's being stored as backup data, that would need to be restored to the primary service, then you may find that performance considerations are less significant than they were for online access. On the other hand, you might also opt to configure this secondary storage as a potential "online" source (many applications can be easily reconfigured to point to a different data source, restarted, and keep on operating). Doing this requires a couple of extra considerations. First, the performance considerations are equal to that of the primary, but more so, you need to be able to replicate data from the primary source to the secondary source in near real time.