If the array that failed was non-recoverable then yes, all data they had in common would be lost.   Data is striped across members in the same pool is done in proportion to their relative capacities.  It's a RAID-0 stripe.   That's why it's a good idea to use a higher redundant RAID level like RAID-10, -50 or RAID-6 when you have multiple members in a pool.   Regardless of what RAID level having current backups is highly recommended.   Regards, 
If you have a multi-member group, with one storage pool,  and one array fails, wouldn't you lose all your data since it's written across all the arrays? Thanks Elle 
Multi-member group and node failure?