Storage Area Network (SAN) storage has gotten much cheaper over the last few years. But cloud costs have decreased as well over the last few years, while reliability and security in the cloud have simply gotten better over the years. If you are looking at purchasing a new SAN (either expanding your existing infrastructure or building out a new infrastructure) and you are looking at spending under $100,000 for the storage array, you should strongly consider using the cloud to host your servers instead of hosting them at a local data center.
The reason for this is that inexpensive storage arrays, while the salesperson will tell you are fantastic, aren’t. They typically provide limited views at the CPU and memory usage of the array. They typically have limited support for Redundancy Array of Inexpensive Disk (RAID) level support. And often the numbers of what they are supposed to support often don’t line up. While you can stick 10 high-end SSD drives in the array which each support 30,000 IOPs giving you the ability to push 300,000 IOPs through the array, the array itself may only be able to process 100,000 IOPs through the software on the array, or through the buss which the disks are physically connected to.
The performance numbers between on-premises storage arrays and cloud storage can be confusing. Let’s assume that our storage array that is on-premises can support 100,000 IOPs. When we look at a 1TB drive in the cloud, it will support 5000 IOPs (using a P30 drive in Azure). These numbers seem very different, but remember that the cloud number is only a single drive where the storage array is limited to 100,000 IOPs no matter what. If we have a second virtual server in the cloud with another 1TB disk, that machine gets another 5000 IOPs without any impact on the first machine. This is because the performance of virtual machines in the cloud isn’t impacted by the storage of other virtual machines. Now that 100,000 IOPs that the SAN has still seems pretty high.
In the cloud, with just 20 servers in the cloud, each with a 1TB drive, we can provision 100,000 IOPs. If we need more than 20 servers, and those 20+ servers need 1TB drives, and they all start pushing their IO hard, the SAN will suddenly run out of IO capacity. Where in the cloud everything will keep moving along.
So if you are in the position where you are looking at purchasing a new SAN, and you aren’t looking at spending hundreds of thousands or millions of dollars, look strongly at the cloud.