On Tuesday October 15, vlad@webmail.co.za wrote: > > Now here is the crunch : both RAID 4 and RAID 5 give me EXACTLY the same > results, both in read write performance. I am using many programs for > benching, hdparm, bonnie, iozone, tiobench and the results are > consistent and repeatable. > > Does anyone know with any degree of certainity whether RAID 4 is > supported in Linux? What exactly is the status of that? I know that > there is no point in using RAID 4 over RAID 5 but I want to know so that > I am able to document it. raid4 is definately supported in linux. It is supported by the raid5 driver so there is a possibility of some confusion. However it sounds like you are setting it up correctly. You would only expect to see a performance difference between raid5 and raid5 when doing lots of small widely distributed random writes. You would probably also need a fairly large array (at least 5 drives) to be able to measure much and you would need to be sure that none of the busses are in a position to cause a bottle neck. Basically you need to get the raid4 parity drive overloaded with parity read/updates before you will see it slow down. NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
