Mirror/RaidZ2 clarification

[Yell]

Hello,
the following two questions drives me nuts, i hope someone can help me.

1) I assume the following command would create a stripe over mirrors (aka raid 10)

Code:

zpool create tank mirror disk1 disk2 mirror disk3 disk4 mirror disk5 disk6

A) In case one mirror fails (disk5&6), all data is lost ?
B) Is it possible to create a JBOD over mirror pairs and can i still access the data from disks 1 to 4 if the disk5&6 fail?

2) How does ZFS align a RaidZ2?
Case A

Code:

Disk1    Disk2    Disk3    Disk4    Disk5    Disk6
Data     Data     Data     Data     Parity   Parity
Data     Data     Data     Data     Parity   Parity     
Data     Data     Data     Data     Parity   Parity   

Case B

Code:

Disk1    Disk2    Disk3    Disk4    Disk5    Disk6
Data     Data     Data     Data     Parity   Parity
Parity   Data     Data     Data     Data     Parity     
Parity   Parity   Data     Data     Data     Data   

Case C
???

 

[ben]

1)
A) Yes, all data will be lost.
B) No, this is not avoidable when striping mirrors.
2)

Code:

Disk1    Disk2    Disk3    Disk4    Disk5    Disk6
Data     Data     Data     Data     Parity   Parity
Data     Data     Data     Parity   Parity   Data     
Data     Data     Parity   Parity   Data     Data
Data     Parity   Parity   Data     Data     Data
Parity   Parity   Data     Data     Data     Data
Parity   Data     Data     Data     Data     Parity

This is my understanding. RAID-Z2 allows two disk failures, it works basically like RAID 6.