Fault-Tolerance

To test how good the controller can secure the stored data in case one of the array drives fails, we imitated the typical “emergencies” for RAID 1, RAID 5 and RAID 10.

It turned out a much easier task to cause a SATA drive failure compared to the good old PATA HDDs. Since the WD Raptor drives can be powered via the old power supply connector as well as via the SerialATA one, it is pretty easy to imitate a drive failure by simply unplugging the SATA cable.

Intel SRCS14L controller reported a drive failure in all three cases and after a short pause started restoring the array integrity by using a HotSpare disk (in case of RAID 1 and RAID 5). For RAID 10 emergency we disconnected one of the drives, waited for the array indication in Degraded mode, replaced the failed drive and made sure that the controller recognized a new one and started restoring the array. I should say that the “pause” took much longer in the latter case than for the HotSpare drive. Moreover, during this pause the controller didn’t do anything at all…

Restoring the array under workload (that is when the controller not only checks the data integrity and regenerates it, but also processes user requests) takes a lot of time and we couldn’t wait until it is completely over. Therefore, we simply unloaded the controller (terminated the test) and waited for the array restoring to be completed.

It took about 30 minutes to restore RAID 1 array, while RAID 5 and RAID 10 required a bit over an hour.

Conclusion

So, the benchmark results for the Intel SRCS14L controller show that it managed to pass all the tests pretty successfully. We saw it adjust the array scalability depending on the number of hard disk drives involved, save the data in fault-tolerant arrays (such as RAID 1, RAID 5 and RAID 10).

At the same time, we have to admit that it proved quite slow in many work modes. Here I definitely have to stress its poor performance in RAID 5 and RAID 10 arrays when the workload wasn’t that high, as well as pretty low read speed from RAID 5 array…

As for the performance of Intel SRCS14L controller against the competitors, we are going to discuss it pretty soon, so stay tuned! :)