[Lustre-discuss] Not sure how we should configure our RAID arrays (HW limitation)

[Frank Riley]

> How about doing 3 4+2 RAIDs?  12 usable disks, instead of 14 or 16, but still
> better than 8 with RAID1.  Doing 4*128KB, resulting in 2 full-stripe writes for
> each 1MB IO is not that bad.

Yes, of course. I had thought of this option earlier but forgot to include it. Thanks for reminding me. So using a stripe width of 512K will not harm performance that much? Note also that the E18s have two active/active controllers in them so that means one controller will be handling I/O requests for 2 arrays, which will reduce performance somewhat. Would this affect your decision between 3 4+2 (512K) or 2 7+2 (896K)?