As an addendum to a previous blog entry, I built a RAID-1E array with three identical 500GB disks and ran some benchmarks. As expected, the results fell somewhere in between the pure HDD and RAID-0 performance for both reads and writes.
Version 1.97 ------Sequential Output------ --Sequential Input- --Random- Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP XXXX 23944M 888 96 178362 11 90639 5 5192 88 253139 7 557.7 11 Latency 8913us 4412ms 6268ms 17400us 38206us 764ms
Therefore, the advantage that it has over a RAID-0 array is the redundancy aspect as a RAID-1E is capable of withstanding a single-disk failure unlike RAID-0. However, performance suffers slightly. It is both faster and safer than a single HDD storage.
Therefore, a RAID-1E configuration is quite useful.
As for how to build a RAID-1E array, just build a RAID-10 array with an odd-number of disks. Useful, when I only have three identical disks.