Performances in Raid 6
We finish with a few tests of Raid levels that are less often an option.
In Raid 6, the first thing that jumps to our attention is a loss of performances in writing compared to Raid 5. This is roughly 5% for Thecus/SMB and even as high as 19% for the Qnap/SMB! In FTP, it really shows on the Thecus because the loss is 16% versus -14% for Qnap.
In reading, performances are equivalent with minimal differences (1%), sometimes more, sometimes a bit less.
In short, if you want security for a two drive breakdown, consider the possibility of creating a spare Raid 5 + storage instead of Raid 6. Performances will be higher and the security almost identical. We say ‘’almost’’ because, in the case of a hard drive breakdown, the system is no longer protected for roughly ten hours or the time that the spare drive is initialized and integrated to storage.
At any rate, the security is there and we repeated the same test procedure as in Raid 5 although this time unplugging two drives. We had no problems to report for any system.
Performances in Raid 10
The above conclusion is also valid for Raid 10. If we gain in reading (up to+6.8%), it’s largely insufficient in compensating for the losses in writing (up to 16%). This does not include the fact that there is not exactly the security for a two drive failure because when it happens in the same sub-volume, all data is lost.
