Both controllers we have tested today have a number of conspicuous peculiarities that should be taken into account when you are choosing a controller for a specific load. For example, the Promise SuperTrak EX8350 was better with RAID6 arrays and with real files, and at multithreaded reading, but its performance under typical server load was far from ideal. It is not good at multithreaded writing, either. You shouldn’t make the EX8350 write in more than two threads. But it loses less speed when the array becomes degraded and supports a backup battery which may be important for some users.
The HighPoint RocketRAID 3220 coped well with server load and multithreaded writing but had problems when working with files, with degraded RAID5 and RAID6 arrays, and with very large data blocks. Neither controller was brilliant at sequential operations, so we would recommend you to consider other models if this load type is important to you. The developers surely have got a lot of work to do on these products, and we hope that other controllers from these brands (for example, from the later released series with SAS support) are free from the drawbacks we have mentioned.
When it comes to the controllers’ operation with degraded arrays, there is of course a performance hit, sometimes very heavy. As we might expect, it is the speed of reading from such “half-dead” arrays that suffers the most. It means that the response speed of various databases stored on such arrays will drop considerably. However, if you keep this fact in mind and ensure a certain reserve of performance, an array with failed disks can go on working more or less well. You just should not keep the array in its degraded state for long but replace the failed disk as soon as possible. The next disk may fail much sooner than you can expect basing on statistical probability laws.
This review may be one of our last reviews of RAID controllers following the current methodology. We are not going to change our benchmarks or abandon such test sessions altogether. The fact is that modern servers are transitioning to SAS drives with high spindle rotation speeds and, accordingly, with lower response time and higher performance. Even “ordinary” drives have already stepped beyond the 100MBps milestone in sequential operations. There have appeared affordable but very fast VelociRaptor drives from Western Digital. So, we are considering a change of our testbed because our rather old WD Raptor2 drives cannot now load advanced modern controllers well enough.