Hi  I have decided to go with RAID 6 . Thx for your help !
Hi all  I have PowerEdge 740 . I have added 8 new disks (2.4TB each) . I'm trying to decide between RAID 5 AND 6 . The system is used for deep learning so the writing rate should be high . This is something only RAID 5 can offer because it uses only one parity disk . On the other hand it can take only one hard rive failure at a time . RAID 6 can save me if/when 2 hard drives are failed , but since it's using 2 parity drives the performance decreasing . Also , while RAID 5  takes only one drive for the parity (2.4TB) , with RAID 6 I'll lose 4.8TB Since the performance is important to us it seems RAID 5 would be better...  Do you have any useful insight ?  Thx . 
Can't decide between RAID 5 and 6