7

I'm testing S2D now and I would like to calculate MTBF for the whole system. It seems very fragile to me:

Let's have 4 nodes (x) with 12 drives (y) in each. MTBF for one node is 1/12 of single drive value. For three-copy mirror we can tolerate 2 node failures (equals two failed disks in different nodes). That gives me 2/4 MTBF of single node value. In total it is 1/24 or 2/(x*y) MTBF in comparison to single drive.

This value is quite low and gets even lower for larger deployments. Is my calc correct? I know that Microsoft recommends to reserve capacity of 2 disks in the pool aka hot-spares, but is it sufficient for production use?

Jan Zahradník
  • 547
  • 5
  • 14

1 Answers1

7

Microsoft recommends % of usable capacity, "2 disks" is too bold statement for say 90 disk JBOD.

BaronSamedi1958
  • 12,510
  • 1
  • 20
  • 46