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Cloud storage options: Public vs. private vs. hybrid cloud storage

Cloud storage options include public cloud, private cloud and hybrid cloud storage. We weigh their scalability, security, performance, reliability and cost.

What you'll learn in this tip: Cloud storage options for your company include public, private and hybrid cloud storage. Find out how each one compares in terms of scalability, security, performance, reliability and cost—and learn how to determine which one is right for your data storage environment.

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 data storage.

The benefits of cloud storage technology

The benefits of using cloud storage technology 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.

The technology 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 base and peak loads are its most appealing characteristics.

Public cloud storage 

Public cloud storage services are a cloud storage option 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 cloud storage is 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.

Internal or private cloud storage 

Internal or private cloud storage runs on dedicated infrastructure in the data center and, as a result, address the two main concerns of security and performance, but otherwise offers the same benefits of public cloud storage. Internal storage clouds are usually for a single tenant, even though larger enterprises may use multi-tenancy features to segregate access by departments or office locations. Unlike their public cloud storage counterparts, scalability requirements are more modest, so internal cloud storage offerings are more likely to have traditional storage hardware under the hood. A case in point is Hewlett-Packard (HP) Co.'s CloudStart, which combines HP BladeSystem Matrix, an HP StorageWorks Enterprise Virtual Array (EVA) Family array and Cloud Service Automation (CSA) software into an internal cloud storage infrastructure. HP CloudStart by itself isn't a private cloud storage offering because it lacks the key element of being service based; instead, it's the enabling infrastructure that could be used by HP, one of its partners or even enterprises to offer it as a fully managed, pay-as-you-go cloud storage offering.

An example of a private cloud storage offering is the Hitachi Data Systems Cloud Service for Private File Tiering. Based on the Hitachi Content Platform (HCP), it resides in the customer's data center but is owned and managed by Hitachi. Besides an initial setup fee, the customer pays for it by usage. Similarly, Nirvanix hNode provides a fully managed, pay-as-you-go, internal cloud offering within the data center, based on the same technology that powers the Nirvanix Storage Delivery Network (SDN).

Hybrid cloud storage

Users who have a hybrid cloud storage environment manage resources both externally and in-house. Because hybrid cloud scenarios often provide an on-site appliance, they can provide local cache and memory, data deduplication and encryption for an IT shop's data.

However, a hybrid cloud solution must meet certain key requirements to make hybrid cloud storage work. They must behave like homogeneous storage, be virtually transparent and have mechanisms in place that keep active and frequently used data on-site while simultaneously moving inactive data to the cloud. These types of clouds also depend on policy engines to define when specific data gets moved into -- or pulled out -- of the cloud. For more on hybrid storage clouds, check out our tip on hybrid cloud implementation.

Public cloud vs. private cloud vs. hybrid cloud storage

The following chart provides a quick overview of available cloud storage options.


Public cloud storage

Private cloud storage

Hybrid cloud storage
Scalability Very high Limited Very high
Security Good, but depends on the security measures of the service provider Most secure, as all
storage is on-premises
Very secure; integration options add an additional layer of security
Performance Low to medium Very good Good, as active content is cached on-premises
Reliability Medium; depends on Internet connectivity and service provider
High, as all equipment is on-premises Medium to high, as cached content is kept on-premises, but also depends on connectivity and service provider availability
Cost Very good; pay-as-you-go model and no need for on-premises storage infrastructure Good, but requires on-premises resources, such as data center space, electricity and cooling Improved, since it allows moving some of storage resources to a pay-as-you-go model

Each cloud storage option discussed here has its pros and cons. Public clouds have high scalability, but often lag in performance. Private clouds generally have high reliability, but limited scalability. And hybrid clouds might offer the in-house control that some companies are looking for, but also tend to cost more. Depending on your specific needs, the size of your environment, and your budget, one of these cloud storage options is bound to be a good fit for your organization.

BIO: Jacob Gsoedl is a freelance writer and a corporate director for business systems. He can be reached at  [email protected].

This article originally appeared in Storage magazine.

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