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For an offering to be considered cloud storage, it needs to be:
- Network accessible
- Service based and paid for by usage
- Elastic, so it can dynamically shrink and grow as needed
- Able to scale up and down on demand
The primary use of cloud storage today is for unstructured data, which is the fastest growing and most voluminous content, causing the most administrative pains. Cloud storage is less suitable for structured data, which continues to live on traditional enterprise storage.
The benefits of cloud storage
The benefits of using cloud storage for unstructured data are compelling, starting with lower overall storage costs. Being service based, there's no storage hardware to buy, manage and maintain, and depending on the service, it can greatly reduce, if not eliminate, data center and storage administrator costs. Cloud storage eliminates expensive technology refreshes that usually kick in three years to five years after the initial purchase, needed to either get state-of-the-art technology or simply to get around purchasing expensive support contracts for older arrays.
Cloud storage can provide close to 100% storage utilization by eliminating the massive amounts of unused storage that are needed with traditional data storage for anticipated growth and peak loads. Besides the overall cost savings, scalability of cloud storage and its ability to transparently support
PUBLIC vs. PRIVATE vs. HYBRID CLOUD STORAGE
Enlarge PUBLIC vs. PRIVATE vs. HYBRID CLOUD STORAGE diagram.
Public storage clouds
Public cloud storage services are offered by a fast growing list of service providers: AT&T, Amazon, Iron Mountain Inc., Microsoft Corp., Nirvanix Inc., Rackspace Hosting Inc. and many others. Their storage infrastructure usually consists of low-cost storage nodes with directly attached commodity drives with an object-based storage stack that manages the distribution of content across nodes. Data in the cloud is typically accessed via Internet protocols, mostly Representational State Transfer (REST) and to a lesser degree Simple Object Access Protocol (SOAP). Resilience and redundancy is achieved by storing each object on at least two nodes. Usage is charged on a dollar-per-gigabyte-per-month basis and, depending on the service provider, there may be additional fees for the amount of data transferred and access charges.
Public storage clouds are designed for massive multi-tenancy that enables isolation of data, access and security for each client. The type of content stored on public clouds ranges from static non-core application data and archived content that needs to be available, to backup and disaster recovery data. Public cloud storage isn't suited for active content that changes all the time. The primary concern of using public cloud storage in the enterprise is security and, to some extent, performance.
This was first published in January 2011