Disk1 (three-way mirror): 2 disks; Disk2 (parity): 1 disk

\In the Administering Windows Server Hybrid Core Infrastructure materials on Storage Spaces resiliency, Microsoft describes how each resiliency type determines simultaneous disk-failure tolerance. The guide explains that mirror spaces keep multiple copies of data: “Two-way mirror writes two copies and can sustain a single disk failure; three-way mirror writes three copies and can sustain the loss of any two disks without data loss.” It also differentiates parity spaces, which stripe data with parity information: “Parity provides capacity efficiency comparable to RAID-5 and tolerates a single disk failure (use dual parity to withstand two failures).”

Applying these to SSPace1:

Disk1 uses a three-way mirror across eight physical disks. By definition, a three-way mirror survives two concurrent disk failures and remains online, satisfying the “always available” requirement.

Disk2 is configured as parity across twelve physical disks. Standard parity (single parity) is equivalent to RAID-5 and survives one disk failure; only dual parity would allow two, but the configuration provided specifies parity (not dual parity).

Therefore, the maximum simultaneous physical disk failures while maintaining availability are 2 for Disk1 and 1 for Disk2.