Disaster Recovery – Silverton Consulting

Facebook friend carrousel by antjeverena (cc) (from flickr)

Cloud storage has emerged as a viable business service in the last couple of years, but what does cloud storage really do for the data center. Moving data out to the cloud makes for unpredictable access times with potentially unsecured and unprotected data. So what does the data center gain by using cloud storage?

Speed – it often takes a long time (day-weeks-months) to add storage to in-house data center infrastructure. In this case, having a cloud storage provider where one can buy additional storage by the GB/Month may make sense if one is developing/deploying new applications where speed to market is important.
Flexibility – data center storage is often leased or owned for long time periods. If an application’s data storage requirements vary significantly over time then cloud storage, purchase-able or retire-able on a moments notice, may be just right.
Distributed data access – some applications require data to be accessible around the world. Most cloud providers have multiple data centers throughout the world that can be used to host one’s data. Such multi-site data centers can be often be accessed much quicker than going back to a central data center.
Data archive – backing up data that is infrequently accessed wastes time and resources. As such, this data could easily reside in the cloud with little trouble. References to such data would need to be redirected to one’s cloud provider but that’s about all that needs to be done.
Disaster recovery – disaster recovery for many data centers is very low on their priority list. Cloud storage provides an easy, ready made solution to accessing one’s data outside the data center. If you elect to copy all mission critical data out to the cloud on a periodic basis, then this data could theoretically be accessed anywhere, usable in many DR scenarios.

Probably some I am missing here but these will do for now. Most cloud storage providers can provide any and all of these services.

Of course all these capabilities can be done in-house with additional onsite infrastructure, multi-site data centers, archive systems, or offsite backups. But the question then becomes which is more economical. Cloud providers can amortize their multi-site data centers across many customers and as such, may be able to provide these services much cheaper than could be done in-house.

Now if they could only solve that unpredictable access time, …

Cloud whisps (sic) by turtlemom4bacon (cc) (from flickr)

When I first heard about cloud storage I wondered just what exactly it was trying to solve. There are many storage problems within the IT shop nowadays ~~day~~s, cloud storage can solve a few of them but introduces more and leaves a few unsolved.

Storage problems solved by cloud storage

Dynamic capacity – storage capacity is fixed once purchased/leased. Cloud storage provides an almost infinite amount of storage for your data. One pays for this storage, in GB or TB per month increments, with added storage services (multi-site replication, high availability, etc.) at extra charge. Such capacity can be reduced or expanded at a moments notice.
Offsite DR – disaster recovery for many small shops is often non-existent or rudimentary at best. Using cloud storage, data can be copied to the cloud and accessed anywhere via the internet. Such data copies can easily support rudimentary DR for a primary data center outage.
Access anywhere – storage is typically local to the IT shop and can normally only be accessed at that location. Cloud storage can be accessed from any internet access point. Applications that are designed to operate all over the world can easily take advantage of such storage.
Data replication – data should be replicated for high availability. Cloud storage providers can replicate your data to multiple sites so that if one site goes down other sites can still provide service.

Storage problems introduced by the cloud

Variable access times – local storage access times vary from 1 and 100 milleseconds. However, accessing cloud storage can take from 100’s of milleseconds to minutes depending on network connectivity. Many applications cannot endure such variable access times.
Different access protocols – local storage support fairly standard access protocols like FC, iSCSI, NFS, and/or CIFS/SMB. Barring the few (but lately increasing) cloud providers that provide NFS access protocol, most cloud storage requires rewriting applications to use new protocols such as REST to store and access cloud file data.
Governance over data – local storage is by definition all located inside one data center. Many countries do not allow personal and/or financial data to be stored outside the country of origin. Some cloud storage providers will not guarantee that data stored in the cloud couldn’t be stored outside the country and jurisdiction of a single country.

Storage problems not solved by the cloud:

Data backups – data protection via some form of backup is essential. Nothing says that cloud storage providers cannot provide backup of data in the cloud but few if any provide such service. See my Are backups needed in the cloud post.
Data security – data security remains an ongoing problem for the local data center moving the data to the cloud just makes security more difficult. Many cloud storage providers provide rudimentary security for data stored but none seem to have integrated strong authentication and encryption services that might provide true data security.
Energy consumption – today’s storage consumes power and cooling. Although, cloud storage can be more efficient than onsite storage, this does not eliminate the environmental cost of storage.
Data longevity – data stored in the cloud can just as easily go obsolete as data stored locally.

Probably some I have missed here but these are a good start.