Shared web hosting and virtual hosting are 100% about resource management. From our perspective we want to maximize our hardware resources so that our customers have the cpu/memory and IO that they need while still having enough customers on a cluster of servers to make it cost effective to sell hosting at a reasonable price.
In my opinion CPU and memory constraints have mostly been solved in the hosting industry. Many hosting companies would disagree with me on that statement, but those that REALLY understand what the bottlenecks are that are hampering the hosting industry know that it is all about Disk IO and poor seek times.
Seek times on hard drives are BY FAR the #1 issue that Bluehost faces in terms of hardware/server performance. It astounds me that so many “techies” don’t get this when I talk to them about servers where hundreds of people shared the same storage either locally or through a NAS/SAN/SAS or other storage device. 90% of the high “CPU Loads” we see have nothing to do with CPU and everything to do with Disk IO blocking, and specifically the inability to seek fast enough to service all IO requests by the kernel. So what can you do?
The answer, in my opinion, is solid state drives. Hard drive technology has stagnated over the past 15 years as little has been done to increase actual disk speed. Sure, capacities have increased tremendously over that same period, but 3.7 ms seek time is still the fastest I have seen. I could buy drives with a 3.7ms seek time 10 years ago. Soild state drives – drives based on flash memory solve this problem. Most of these drives have a seek time of <1 ms, and many offer drives with seek time in the nano second range. These drives offer a tremendous speed improvement when the disk is under heavy IO load. We have implemented some of these devices in scenarios where MySQL databases were migrated to soild state devices, or where the “/” partition was completely overwhelmed by IO. The speed improvements were immediate and dramatic. MySQL was up to 50x faster in some cases and 5-10x speed improvement in database performance was common across the board. This is especially true in a shared hosting environment where many customers simply can’t optimize their databases for lack of time or knowledge.
Solid state drives are expensive and small. They only make sense when you are storing data that is accessed constantly, and that is reasonably small. 4 Gig to 64 Gig drives are common, but expensive. However, in the ultra competitive market of shared hosting every bit counts. You can count on Bluehost to start implementing these very soon as standard fare on all our servers. We have several in production now, but soon all our new servers will have these type of devices to yet again force the performance marker to go up one more notch.
Matt Heaton / President Bluehost.com