SAN Choice - Different point of view
As with all good Network Managers/Senior technicians, we like to do our research before reporting back to the management team with our shopping list.
After reading lots of posts on this site it’s interesting that people regularly ask what SAN to buy and you get the usual answers of speed and performance but the interesting point is why are you taking the decision to buy a SAN without all the facts?
Most Schools have limited access to external advice but why stumble around in the dark, buy a SAN and then realise that you have a lemon.
The one key piece of information required when looking at a virtualisation project is a capacity planning report. Companies like VMware offer a service that installs a small service on one server in your current setup and then collects information on most performance counters, disc capacity and network band width across your entire infrastructure. This runs for a month and produces a report that will tell you exactly what specification you need for your SAN and Hosts.
You really need the help of others on this one if your project is to run smoothly. Many companies offer this service for free as long as you take a quote from them for Hardware etc. This doesn’t mean you have to use them!
When it comes to SAN choice, well there are lots out there but apart from the obvious, look into what a SAN can do for you as an administrator.
• Can it be updated without downtime
• Will it still run if parts fail (Redundancy)
• Can I grow storage without downtime
• Will it tell me when things are going wrong before it fails
• What is the support like? Forums/whitepapers & Blogs
It’s now a year since I went through this process and with a report in hand, I knew that only a few SANs would give us the iops needed to virtualise our 20 physical servers.
We went for an HP P4000 series SAN also known as Lefthand a scale out solution. This put us in control of the storage and not the other way round. The key for us was the network RAID feature that enables data to be raided not just across each node of the storage but across the nodes as well. This means that a whole node could fail and we still have a fully working SAN. We can do software upgrades during the day without disruption and we can allocate extra storage to data stores on the fly. It has simple GUI console that you can install to manage the SAN. The SAN intergrates with HP’s System Insight manager which is free and this monitors our infrastructure and gives real time status of the network. The best thing of all was the cost. We were quoted nearly £300k for a NetApp equivalent and the lefthand came out at a fraction of that and was full featured out of the box. A special bid direct with HP gave us a 50% discount from list and that gave us an enterprise class SAN at entry level pricing.
Don’t make the mistake of buying a fitted kitchen for a house that you haven’t measured up!