In our last blog post, episode 1 – “what the heck is cloud storage?”, we discussed what cloud storage is and some of its attributes. Based on those, it’s apparent why many corporations are interested in being able to take advantage of cloud storage. It’s elastic, inexpensive, and there’s less headache in maintaining complicated storage infrastructure.
So why hasn’t cloud storage taken off?
The truth is, cloud storage isn’t consumable by most traditional applications in your data center. As it is accessed over a WAN (for public cloud storage) using APIs (more often than other access methods), cloud storage has done quite well for custom-built applications where the source code is readily accessible – both in the data center and for applications running on public compute clouds. However, this is not the case when the application expects to speak directly to disk storage using block protocols that carry SCSI, such as iSCSI, FC, and FCoE.
Additionally, many people are nervous about cloud security. In a sense, when you use cloud storage, you’re giving control of your data to a third-party (unless of course you use a private cloud) and introducing a new availability concern (availability being part of the triad of security: confidentiality, integrity, availability). Naturally this brings up questions such as
– “what if my provider loses hardware?”
– “what if my provider’s data center is compromised?”
– “how isolated is my data from the rest of my provider’s customers?”
– “what if my provider is asked to turn over my data?”
– “what if my provider has an outage?”
– … and many more
Alongside the communication issues and security issues are performance issues. Accessing cloud storage involves communication over a network – potentially, the Internet, which is the case in public cloud storage services. All networks – even data center networks – introduce latency, packet loss, bandwidth limitations, congestion, and other issues, all of which can impact performance. Most applications enjoy very high performance access to their storage systems today, because generally speaking the storage is accessed over the local network where these issues are only noticeable in extremely high-throughput environments.
Cloud storage services also lack in the realm of data protection. Many of them will automatically replicate your data to two or more locations, but replication does not solve the issue of providing a consistent copy from a point-in-time in the past. Virtually all companies today rely on snapshots as the foundation of their backup and restore strategy, which when used correctly can create application-consistent, crash-consistent point-in-time copies of application data, to allow the data to be restored in the case of corruption, site failure, data loss, and so on. Cloud storage services generally do not provide this function.
Unfortunately, without addressing these issues, it’s difficult for I/T organizations to take advantage of cloud storage for many of the applications they rely on to power their business.
In the next episode, we’ll talk about how these issues can be addressed. I look forward to your feedback on these items – where you agree, where you disagree, or points I may have missed. Please feel free to use the comments section below and speak up!