In an Isilon Gen 5 environment, what is the maximum number of data stripes for the N+3d:1n1d protection level?
In an Isilon Gen 5 environment, what is the maximum number of data stripes for the N+3d:1n1d protection level?
In an Isilon Gen 5 environment, the protection level N+3d:1n1d refers to a data protection scheme where the data is protected with three disk-level failures and one node-level failure plus one disk-level failure. This scheme requires 3 disks for data protection and 1 disk for node-level protection, leaving a maximum of 15 disks for data stripes to ensure each stripe unit is properly distributed. Therefore, the maximum number of data stripes for the N+3d:1n1d protection level is 15.
Unless there is a Gen5 mechanic i´m not aware of: N+3d:1n1d = N+3/2, meaning 2 active drives per node. Now 16+3 = 19 (duh). 19%2= 1, meaning one of the active drives would have to hold a third stripe unit. Which is why (at least in Gen6 or later) N+3d:1n1d is limited to 15 data stripes (max. stripe width of 18, can be divided by 2).