EMC, the world leader in storage and IT management, developed these Top 10 Tips for SMBs considering stepping up to SAN. The following tips can help you make informed decisions when selecting the hardware and technologies that you use.
Top Ten Tips for Stepping Up to SAN Small and medium businesses (SMBs) with multiple servers typically have their storage held hostage in each individual server. With data growing at 50 percent per year, this kind of storage strategy is difficult to manage and expensive to scale. An elegant and cost-effective solution is to step up to a storage area network (SAN). A SAN moves storage off individual server and onto a disk array where it can be consolidated and shared efficiently among multiple servers. If you're considering stepping up to SAN, the following tips can help you make informed decisions when selecting the hardware and technologies that you use. 1. Determine How You Plan to Use Your SAN Storage Before you start building your SAN, decide exactly what you plan to use it for. Are you consolidating storage consolidation for multiple servers? Are you planning to use the storage for backup to disk? Or will you be doing both? It's easier to make the correct decision about your SAN storage if you have a clear picture of how you plan to use it. 2. Select the Correct Level of RAID Aside from consolidating storage, a disk array can provide fault tolerance by using RAID (redundant array of independent disks) technology. RAID distributes data across the disks on the array, and uses mathematical algorithms to reconstruct data if one of the disks fails. Because RAID requires additional calculations and storage space, the following table helps you choose the RAID level that's right for you. RAID Level Performance Additional Storage Level of protection RAID 0 Excellent Requires no additional storage No protection RAID 1 Very good Doubles the amount of disk space Prevents data loss as a result of required a single hard drive failure RAID 5 Good Requires one additional drive per Prevents data loss as a result of RAID group a single hard drive failure RAID 10 Excellent Doubles the amount of disk space Prevents data loss as a result of required a single hard drive failure 3. Size Your Needs Today and Plan for Growth Determine the amount of storage your SAN requires. If you plan to use the SAN solely for consolidating server storage, add the current disk space being used on every server. Take the total and add 50% per year for growth plus extra drive space for RAID redundancy. If you are using the SAN for backup to disk, take the preceding total and multiply it by two. This provides plenty of room for an initial full backup plus any incremental backups you need to perform. 4. Chose a Name You Can Trust A SAN must be dependable. The performance of RAID disk arrays can vary widely from manufacturer to manufacturer. Select SAN storage hardware from a manufacturer with a proven track record. Review the testing guidelines for the products. And before you make a decision, check industry publications for product reviews and any awards the product might have received. 5. Increase Reliability by Using Redundant Paths to the Disk Array With a SAN, your storage is now external to your servers. If you can't get to it, you're dead in the water. Look for an array that has two Fibre Channel or GigE iSCSI ports. If one path fails your servers can automatically connect via the other path. 6. Use Dual Processors to Increase Throughput Dual processors increase a disk array's speed by providing two processors to handle incoming requests. Requests from the servers are automatically load balanced between two service processors in the disk array.
Top Ten Tips for Stepping Up to SAN 2 Each processor has its own cache, so the array can handle tasks in parallel, which provides a noticeable improvement in speed. 7. Go with Fibre Channel Connectivity for Ultimate Performance If your SAN requires high levels of performance, select use Fibre Channel connectivity, which uses special Fibre Channel host bus adapters (HBAs) and optical fiber. Fibre Channel switches and cables are more expensive and require more expertise to install and manage, but Fibre Channel is a better choice for environments that demand a consistently high level of performance. 8. Choose iSCSI Connectivity for a Cost-Effective Solution If high performance levels are not your top consideration, iSCSI is a natural choice for most SMBs. It keeps costs down by using commodity cables with standard GigE ports and switches, which are also easier to set up and configure for most IT departments. iSCSI can be used with all but the mo... [download for more]
