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Ten questions to help compare cloud storage services

Cloud storage expert Arun Taneja suggests 10 questions to help you successfully compare cloud storage services.

So you've decided to pursue public cloud storage for a particular data set and use case. If you're a developer building a Web-enabled application, then you'll likely be interested in a cloud object store such as Amazon S3 or OpenStack Object Storage. If, on the other hand, you're an enterprise data storage professional looking to take advantage of the cost-effective scalability of the cloud to protect traditional block or file data for backup or disaster recovery (DR) purposes, then chances are you'll want to deploy an on-premises appliance as a gateway to back-end cloud storage. One of the key decision points for each of these use cases -- and a large range of others -- is the choice of a public cloud storage service provider.

While each usage scenario is a bit different, there is a core set of evaluation criteria common to all use cases that you should consider when choosing a cloud storage provider. Here are 10 questions that will help you compare cloud storage services:

1. Does the provider accommodate and support my primary use case(s)? In our example above, companies looking for an object store may find Amazon S3 attractive, but to support the storage of traditional block or file data, an AWS Storage Gateway will also be required. Not all cloud storage providers offer capabilities tailored to use cases such as backup, DR, or archiving, so you'll need to carefully compare the details of each provider's offering.

2. Where will my data be stored? The answer to this question is important for several reasons. First, you'll want to be sure that the provider's datacenter facilities are state-of-the-art, meeting high standards of operational control and security. Look for SAS 70 type II and similar certifications. Knowing the geography in which your data is stored can be important for compliance as well, and may have an impact on data access times: Depending on your data set and use case, you may achieve faster access if storage nodes are located near your corporate or branch offices.

3. What kind of security mechanisms are in place? Look here for strong encryption methods, such as AES-256 and SSL, to secure data at rest and in transit, and sufficient access control and authentication mechanisms to ensure that the wrong person won't gain access to your information. Ask for a published description of the provider's security policies and processes.

4. How does the provider ensure data durability, reliability and availability? You should look for offerings that provide redundancy across multiple facilities and systems within each facility. The provider should perform regular data integrity checks to protect against corruption. Versioning enables additional protection, by allowing multiple versions of objects to be stored, retrieved and restored in case of failures or unintended user actions. Finally, the provider's service-level agreement (SLA) will spell out storage availability commitments. Look for a minimum of three nines (99.9%) availability over each monthly period and 10 or 11 nines of durability over a year, with the ability to withstand and sustain the concurrent loss of data in one or two facilities.

5. How easy is it to upload my data, especially when moving large data sets into the cloud? For this purpose, check out whether the provider offers a data shuttle (portable storage device) or dedicated high-speed connection for seeding initial data into the cloud.

6. How easy does the provider make it to transfer data out of the storage cloud? The answer to this question hinges in large part on the application programming interfaces (APIs) the provider supports: Industry standard REST APIs will ensure that your data is portable, while proprietary APIs may be the first step to vendor lock-in. The overwhelming majority of cloud storage providers now support a REST-like API, so it's worth looking for that in particular. One other thing to qualify upfront is the cost of transferring data out of the cloud. Most providers charge little to nothing to move data into their clouds, but do charge for data transferred out.

7. What kind of access performance does the provider support? Speed of access will be based in part on the location of your data, as mentioned above. If you're planning to store primary data in the cloud, you should evaluate the use of an on-premises cloud storage gateway, which will provide local caching of frequently accessed data and may also compress and deduplicate data before it is sent to the cloud.

8. Will the provider help me to comply with key industry regulations? If your business is subject to major regulations, such as HIPAA or PCI DSS, you'll need to know the geographic location of your data, and you'll likely also need evidence of various certifications before sensitive data can be moved to the cloud. Compare each cloud storage providers' offerings to understand what level of regulatory compliance is built into their cloud storage services.

9. Can I be certain that the provider will still be in business five years from now? If you're considering working with someone other than a major, well-known provider, you'll want to check out the provider's financial stability and track record, to ensure that your data will be in good hands.

10. Can I count on a quick response from the provider's technical support team, in case I run into problems? Many providers now offer multiple tiers of support, including across-the-board 24x7x365 access, as well as named contacts.

About the author:
Arun Taneja is a regular contributor and the founder and president of the Taneja Group, an analyst and consulting group focused on storage and storage-centric server technologies.

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