RAID0 is a stripe, which is fast but has no redundancy. RAID1 is a mirror which is faster than a single disk, but not as fast for read operations as 3+ disks (RAID1 is just 2 disks). RAID5 is a stripe with parity which is faster on read operations than RAID1 but not ideal for write operations because it is required to calculate a parity block of data.

A combining of these different RAID levels gives us the option of RAID10. RAID10 is really RAID1 + 0. So, you can a few disks (at least 4 and always even numbers) and mirror the drives two at a time. This gives the redundancy. Then you take those mirrors and combine them into a RAID0 stripe. This allows redundancy, faster read operations, and fast writes (avoiding a parity calculation).

RAID10 is an extremely fast and very attractive RAID options for performance reasons. But, on the downside, it has a 50% space waste ratio. It also requires more disks than the other options (4 and many people opt for 6 or 8). The larger number of disks generally means a larger server chassis and/or a SAN device. Great options as long as the project has the budget for it.

Before jumping into a RAID10 configuration thinking that it is the best for your project, look at the current performance and configuration. One fairly "easy" way to increase performance is to move from SATA to SCSI drives (we only run high-performance SCSI drives at ORCS Web).

If you are already running SCSI drives, consider bumping from 10k to 15k RPM to gain both some IO/s and MB/s performance. According to various manufacturers that I've spoke with over the years, a move from 10k to 15k RPM drive gains an almost 30% increase in IO performance and a 20% gain in MB/s of throughput.

Architecture consultation and performance assistance is one of the many services we provide at ORCS Web. Check us out if you haven't already. Here is some information about us to help understand how we differ from other hosts.

Happy hosting!

~Brad