What to Look for When Buying a Storage Area Network (SAN) in 2013?
When looking at purchasing a new storage area network, or SAN device, there are many aspects that a buyer must look at. The reasons a new storage device must be purchased may seem basic, such as fulfilling capacity requirements and growth, the current SAN running out of disk space, and end of life for support. The other reasons to acquire a new storage area network may need a more granular look.
First, a person should identify how a new storage area network (SAN) will improve upon the IT environment. One of the main functions of IT may be to support business critical applications such as high performance databases, virtualized servers or desktops, e-mail servers, and websites. This area should be considered when a person is looking to buy a new SAN device. One strategy is to find out how much IOPS (Input/Output per second) each server uses on the SAN. This may be determined using a couple different applications, such as Windows Performance Monitor or IOMeter (http://www.youtube.com/watch?v=XkOUGbsnGn0). A person should determine the number of IOPS needed for each application and then determine the amount of IOPS required for the new SAN, while considering future growth.
If the IT environment does not require a lot of IOPS, then a SAN device with just a bunch of Hard Disk Drives (HDD/Spinning Disks) may be implemented. How much IOPS do hard disk drives deliver? Hard disk drives vary in speed with high speed drives ranging at 15,000 RPM and mid-range drives spinning at around 10,000 RPM and low-end drives running at 7,200 RPM. 7,200 RPM drives typically deliver 75-100 IOPS, 10,000 RPM drives average 100-130 IOPS, and 15,000 RPM drives average 150-190 IOPS (http://www.techrepublic.com/blog/datacenter/calculate-iops-in-a-storage-array/2182).
So, how much IOPS do solid state drives (SSD) produce? According to Intel, their enterprise class (MLC) SSD drives can deliver up to around 8,600 IOPS for random writes (http://ark.intel.com/m/products/56600/Intel-SSD-X25-M-Series-160GB-2_5in-SATA-3Gbs-34nm-MLC?wapkw=8600+iops). For people who need a high amount of IOPS from their SAN, it would be logical to achieve that using SSD drives, instead of adding enough HDD drives in order to enable the use of high performance databases, business critical applications, websites, and virtualization deployments.
What to look for in a SAN if IT needs to improve performance of applications
- Look for a SAN with SSD drives and technologies for quickly reading and writing data
- Watch out for over provisioned SANs. SSD can be expensive and an all SSD array may be overkill and cost prohibitive. Look for a SAN that is able to combine SSD drives with Spinning disk to lower the cost per gigabyte, while maintaining IOPS for key applications
Performance is not the only indicator to look for when buying a new SAN. There are other strategies that IT managers may want to look at when purchasing a new SAN. One key component is replication. A storage area network that is able to replicate Asynchronously to another storage area network could provide a means to a strong disaster recovery strategy. Asyncrhonous replication would allow an organization to recover from a disaster after a period of time conducting recovery operations. And SANs that are able to synchronously replicate over a wide area network, could provide a strategy for high availability if disaster struck. This means that an intelligent SAN who could Asynchronously or Synchronously replicate could provide strategies for disaster recovery and business continuity, replacing old backup software and hardware appliances and licensing.
What to look for in a SAN for providing a Disaster Recovery or Business Continuity/High Availability Strategy
- Look for the ability to Asynchronously and/or Synchronously replicate.
- Watch out for replication licensing. Licensing can get expensive depending on how the manufacture licenses the technology.
Data growth is another factor when looking at purchasing a new SAN. One strategy for determining data growth is to look at data growth over a period of 12 months. Look at the different applications which contribute to data growth and determine if the trend will continue to grow based on overall business goals and objectives. The mathematical formula y=mx+b may also be used to determine future growth based on past growth rate of change. A high rate of data growth can be expensive, when considering the need to purchase new drives and new storage area network devices support capacity requirements. Technologies have been developed to help negate the financial burden of continuing and sometimes rapid data growth.
These technologies include De-Duplication, Compression, and Thin Provisioning. De-Duplication is a process where a storage system will recognize incoming data that has been previously written to disk, and merely reference the already written data instead of writing new data to disk. This is a difficult technology to achieve and different SAN vendors do De-Duplication differently. Compression is implemented by using an algorithm that is able to use fewer bits to achieve the same amount of data that is written. Thin Provisioning, simply stated, removes white space from data. It only provisions data that is actually needed/written. A person can think of thin provisioning as rationing. During the course of history in the United States, the Federal Government has mandated that only those who really need gasoline may purchase it based on their needs. Thin Provisioning can be thought of in the same way, that it provisions capacity to what is actually needed. Another way to think of thin provisioning is to look at the current used capacity of a hard drive. If 100 GB is allocated, and only 25 GB is used, Thin provisioning would only allocate 25 GB, however, would let the user know that 100 GB is available when needed.
The three technologies, compression, de-duplication, and thin provisioning is an intelligent way to negate rapid and continuing data growth. Some studies show that these technologies can reduce data growth by up to 50%. The financial impact of such technologies could be substantive. Again, however, licensing these technologies may be costly, depending on the way the manufacturer does licensing.
What to look for in a SAN for reducing future data growth, when data growth is a concern
- Look for guarantees of savings with technologies like De-Duplication, Compression, and Thin Provisioning
- Watch out for licensing costs
In general, there are a lot of different strategies and methods one can measure to determine the best way how to buy a SAN that will meet required criteria. It is recommended that a storage architect from a value added reseller or vendor be selected to discuss business objectives and requirements when looking to buy a new storage area network. Oftentimes these individuals are willing to consult on the basis that they believe their solution will be the solution that is chosen and purchased, because it is the overall best solution provided. Most of the time this service comes at no cost.
