Exam SK0-005 topic 1 question 338 discussion

Why the Other Options Are Incorrect: B. OS - One SSD RAID 0, DB Logs - One SSD RAID 0, Data - Eight 1.2TB 15K SAS RAID 6: RAID 0 offers no redundancy for the OS or DB logs, which violates the requirement for redundant OS disks. RAID 6 provides high redundancy (tolerates two disk failures), but it sacrifices write performance, which is not ideal for real-time data processing. C. OS - Two SSD RAID 1, DB Logs - Two SSD RAID 1, Data - Eight 1.2TB 15K SAS RAID 5, No hot-spare disks: While this setup meets most requirements, the absence of hot spares leaves the system vulnerable during rebuilds after a drive failure, reducing overall reliability. D. OS - Two SSD RAID 0, DB Logs - Two SSD RAID 1, Data - Eight 1.2TB 15K SAS RAID 5, No hot-spare disks: RAID 0 for the OS provides no redundancy, which is unacceptable for critical systems. Additionally, the absence of hot spares weakens fault tolerance.

C. Personal feelings aside (and mentioned later) it's the most capacity and provides OS redundancy. I absolutely abhor this answer, because the big thing with RAID 5 is hot swappable redundant disks, and not having any spare disks is borderline painful, but having all 8 disks active means you have more storage than having 6 of the disks active and 2 spares. In an ideal world, C would be 7 active and 1 spare drive, but that's not what it is. Given RAID 5 loses the equivalent of 1 complete disk to parity information, the difference is 7TB with 2.4 sitting on the shelf, or 9.4TB with nothing sitting on the shelf for when a drive fails. It goes against every best practice I have ever run up against, but C is technically the most correct answer, even if it's not "best practice."