We’re currently in the process of configuring our very first EqualLogic storage unit. It’s a model from their PS Series, and it gives us a total of 6.5 terabytes of storage in a RAID 50 configuration. We’ve only had it live for about a week now, but we love what we’ve seen so far.
The ease of setup and configuration are light years ahead of what we had on our old fiber channel SAN. While our old SAN provided plenty of storage, configuration and management always seemed to involve a call to our vendor, and even then things never seemed to go smoothly. Based on a few days with the EqualLogic unit, I’m reasonably certain that the calls to the vendor for hand-holding are going to be few and far between.
Besides the ease of use, some of the things we love include the ability to utilize what EqualLogic calls thin provisioning. This enables us to create a 500 GB volume while only using 50 GB of actual drive space. The host OS sees a 500 GB volume, but we’re only using 50 GB on the SAN. As the space begins to fill up, the space used on the SAN also begins to approach the 500 GB allocation, but it gives you a way to actually allocate more space than you have initially. Obviously, this is a feature that you want to be careful with, because overuse could result in the SAN actually filling up on you if several of these thin provisioned volumes filled up at the same time. The unit provides plenty of warnings to alert you as these volumes approach a level of your choosing.
The snapshot feature is another feature which we are learning to love. When you provision a new volume, you can simply choose to save snapshots of the volume at whatever interval you choose. Want a daily snapshot for backup purposes? No problem. Want to snapshot a volume prior to an update? No problem. The snapshots are differential copies, so they take up very little space. Any one of these snapshots can be mounted as a physical volume used to quickly restore individual files or an entire volume if necessary. Here’s a real life example- currently we have a thin provisioned volume which is taking up 96 GB of actual disk space (the host OS sees it as a 500 GB volume), and we have taken 10 daily differential snapshots of this volume which are currently utilizing 1.36 GB of space.
Obviously, the unit also provides all kinds of built-in redundancy, with dual controllers, power supplies, fans, and 14 total disks. Short of lengthy power outages or losing the entire server room, not much is going to take this product down. We’re just scratching the surface of what the box will do, and we have plans to do a lot more with it. In the coming months we’ll migrate our VMWare and Exchange storage to this unit, and we also plan on utilizing the snapshots and replication features into our evolving disaster recovery strategy.