Known issue: total drive number

[Leo-Yan]

So far, the total drive number = good drive number + failed drive number.

In this formula, the "good drive number" is for the drives which can be found its SG node, and has got rid of the duplicate PVs.

"failed drive number" is for the drives which cannot be found the corresponding SG node. Since we cannot find the block device name or cannot find the SG node, so the lock manager has no chance to detect if there have duplicate PVs or not.

As result, "total drive number" might contains duplicate PVs which comes from the "failed drive number"; it's harder to achieve majority since the denominator is enlarged for majority calculation.