ZFS FREENAS Raidz2 2/3HDD fails


Is there any fix with my pool.

At first it was only degraded because one of the hdd have unreadable (pending sectors) after it finish silvering I'm about to replace the drive then after reboot the other drive had unreadable (pending sectors) too and now my pool state was unknown I just need to up my storage so I can back up my files in this array. Here is the current alerts in my system.
Device: /dev/ada1, 2 Currently unreadable (pending) sectors
Device: /dev/ada1, 3 Offline uncorrectable sectors
Device: /dev/ada2, 9 Currently unreadable (pending) sectors
Pool StorageVault state is UNKNOWN:
Im sorry SirDice i am using raidz1 and 2 of my hdd went offline because of unreadable and uncorrectable sectors. is there a way to forcefully mount my pool even with those sectors just to salvage some important files?
I successfully mounted again my zpool but one of my drive is failing and always offline my problem is it is an array of 3pcs of 4tb hdd can I replay the failing one with a love capacity 2tb? 2tb is my only spare on hand and i just want to salvage my files in the pool currently i am occupying 2tb of files in the array of 3pc 4tb raidz1 configuration.
Thank you for all of your suggestions and recommendations. I finally found the solution by importing again my zpool and waiting it to resilver then after that I have the chance to back up my files but after sometime 2 disk will go offline because of numerous errors I'll just let it rest for the day and power on the machine the next day and repeat the process of importing and waiting to for it to resilver so I can continue backing up my files and start again where the copy failed or ended.