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Breaking down SAN technologies

How do you determine which SAN technologies are right for you? Start by figuring out which features are most important for your environment.

This is the second in a three-part series about the role of the storage area network in midmarket organizations. In the first article, the various types of SAN solutions were explored. In the second part of this series, the author dives deeper into the individual capabilities of SAN technologies.

Expensive, high-end SAN technologies may be nice -- but many midsized organizations simply cannot afford them. To find your IT shop's perfect technology fit, first determine your basic storage needs and requirements, then focus on the technology options to meet those needs. Also important is being able to pick out some of the optional features that often come with higher price tags. Avoid them if you can't afford them.

Let's look at some of the options and their purposes. This will help you better determine which features are most important for your environment and which you might want to skip.

Some of the common features and functionality for midmarket SAN storage solutions include:

Management tools: Ease-of-use management tools such as command-line interface, graphical user interface, application programming interface and Simple Network Management Protocol integration for event notification should be standard offerings. Any additional tools should enable ease of setup, configuration and ongoing management tasks for snapshots, replication, allocation monitoring or diagnostics.

Mirrored read/write cache: Boosts performance for read and write operations with redundancy to provide availability should a controller fail.

Hot spare disk drives: Enables failed disk drives to be dynamically replaced in conjunction with automatic disk rebuild via RAID protection.

Redundant power and cooling: Offers hot interchangeable power supplies and cooling fans to eliminate single points of failure. This provides reliability, availability and serviceability.

Dual or redundant controllers: Provides high availability to isolate a component failure while enabling workload balancing for performance.

Flexible and saleable capacity: Enables boost storage capacity by adding additional disk drives into open slots or by adding extra expansion enclosures.

Multiple RAID levels: Provides data availability and accessibility with potential for performance boost depending on configuration.

Virtual arrays or RAID groups: Enables virtual arrays to simplify management and align performance, availability, capacity and other service characteristics to application needs. Implementations will vary according to how many and what type of disk drives can be mapped.

Logical unit numbers (LUNs) and mapping/masking: Meets specific application requirements. Mapping enables a LUN to be securely accessible by only authorized servers. Masking enables a LUN to be visible to other servers.

Security features: Includes encryption for data protection and authorization and authentication for access to management tools.

Point-in-time copy snapshots: Enables on-the-fly backup or data protection, without the overhead or time required to perform a traditional offline backup.

Full-volume copy: Enables an entire volume or LUN to be copied for upgrades and moved to support technology replacements or other infrastructure resource management tasks.

Replication: Uses local or wide-area replication to make a copy of the data in a different location on a separate storage system to enable business continuity, disaster recovery and high availability.

Tiered-storage mediums: Includes solid-state drive (SSD), fast Fibre Channel (FC), serial-attached SCSI (SAS) or high-capacity Serial Advanced Technology Attachment.

Application integration: Supports integration and ease of use with virtualization hypervisors (VMware, Hyper-V, etc.), and databases (Exchange, SharePoint or Oracle).

Ease-of-use management tools such as command-line interface, GUI, API and SNMP integration for event notification should be standard offerings.

Optional items include:

Intelligent power management: This addresses power, cooling and green IT concerns and includes drive spin down, MAID 2.0, variable power and performance levels.

Thin provisioning: This enables disk storage capacity to be highly utilized to help reduce costs or maximize physical storage resources. Note that, by itself, thin providing only boosts storage capacity; other techniques are needed for enhancing performance.

Compression and deduplication: This can reduce data footprint impact by either requiring less physical storage or by stretching available storage capacity to house more data.

Data movement and migration capabilities: These build on previously available full-volume copies to ease data migration across various tiers of storage mediums, including SSD or fast FC and SAS disk drives.

The interface or block-based access for SAN solutions varies from vendor to vendor. Some vendors support only iSCSI, some support a mix of iSCSI and Fibre Channel, and others provide a mix of iSCSI, Fibre Channel and network attached storage (NAS). This flexibility allows you to adapt your storage solution to your particular environment.

Some vendors that do not support native NAS or iSCSI can do so via gateways, bridges, routers or appliances. The gateway approach enables flexibility, but it may introduce another layer of technology complexity depending on the implementation.

To ensure that you're getting the best deal, ask the following questions during your initial vendor evaluations:

  • What are the cost/benefit tradeoffs of nice-to-have vs. need-to-have features?
  • Are there any hidden, up-front or recurring licensing or maintenance costs?
  • How will the solution scale or adapt to changing needs?
  • Does the solution support integration with your IT environment and applications?
  • What changes or upgrades will be needed on your servers or applications?
  • What training, education, knowledge transfer or professional services are included?

Arm yourself with a solid understanding of your needs (including your business and IT requirements) and technology options before you buy -- an informed IT buyer will make better decisions.

Bottom line: Look for storage technologies that meet or exceed your needs, is flexible and resilient enough to adapt to your changing business needs and provides (at no extra cost) some of the nice-to-have features.

Greg Schulz is founder of The Server and StorageIO Group, an independent IT Industry advisory and consultancy. He has authored the books The Green and Virtual Data Center  (CRC) and Resilient Storage Networks. Find him on Twitter @storageio.

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