SAN purchase factors include cloud storage and I/O performance

We outline the factors to consider when making a SAN purchase, including cloud storage, data migration, I/O performance and maintenance issues.

What are the key factors to consider when purchasing a storage-area network (SAN)?
When making a SAN purchase, there are a number of factors enterprise data storage managers need to evaluate, including cloud storage, green storage, I/O performance and maintenance costs.

Cloud storage: Cloud storage is a fairly new consideration. If you'd rather just let someone else deal with your data storage infrastructure, then public cloud storage must be a consideration. But because many things are still being worked out for cloud storage, it might take a while before you have all the answers you need. Some things you need to look at are security, service-level agreements (SLAs), cost and your service provider's infrastructure.

Data migration: What tools exist to handle data migration from an old to a new array? Is moving from vendor A to vendor B likely to be a logistical nightmare?

Functionality: Is disaster recovery (DR) and business continuity (BC) a consideration, and if so, then what functionality do you need?

Array-based replication, snapshots and data deduplication are effective tools, but are they worth the cost? If you only need some of the functionality that these tools provide, can a software product give it at less cost?

Hidden costs: Every vendor will tell you about the capabilities of their array, but many will often forget to mention that some capabilities will cost extra. Make sure you have considered everything you might need so there are no surprises six months down the line, like discovering your new controllers need an additional, costly licence to use CIFS.

I/O performance: If your database demands so much I/O that it requires you to fill up 120 slots, how much I/O does that leave for the rest of your environment? Do you have up-to-date and reliable I/O information for your Oracle, SQL databases and Exchange email databases? Can you forecast how much I/O you'll need over the next five years? If your performance stats show your Fibre Channel SAN is overspecified, have you considered moving to an iSCSI SAN or a NAS appliance?

Maintenance costs: You need to determine how much it will cost to get an array fixed within a time that is acceptable to the business by examining a few factors:

    • What's included and excluded from the maintenance agreement?

    • Will you need to pay for each disk or does the agreement cover the whole shelf?

    • What's the projected lifespan of the array: Is it end of life in three years or 10 years?

  • After the pre-determined lifespan ends, will the array suddenly become so expensive to fix that it would make more sense to buy another one?

Maintenance support network: Who do the support engineers work for? You need to ensure that support engineers with knowledge of the specific version of the array you purchase are always available.

Power and cooling: Green storage issues are important, and you should look for technology that reduces heat and power consumption. Any vendor that ignores this aspect should be avoided. Consideration also needs to be given to the disposal of the old array once the new one is online.

Training: You should determine the expertise and capabilities of your staff before selecting a vendor. For example, what effect will purchasing a NetApp array have on your staff if they're all Hewlett-Packard (HP) experts?

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