I’m trying to decide on drives for a 24 bay chassis (9271-8icc w/ CacheVault & Intel 36 port expander) and I’ve come to the realization that I just can’t have it all.
Among my goals are:
- lower power (7200 and lower RPM as I’ll use SSD caching to make up some of difference),
- higher capacity (8TB and higher thinking fewer drives would equate to less power),
- SAS interface for better protocol support and dual ports, and
- a 10^16 UER (unrecoverable error rate).
However, I’m finding products that are more like 7200RPM, SATA, 8TB/10TB, and 10^15. This makes me think that these larger drives are not connected to a software or hardware RAID array but more to a storage pool where multiple copies of data are kept on multiple, unassociated drives. I think this because when you calculate the 10^15 UER of 12x 10TB drives in RAID 6 you statistically have an 80% chance of encountering one. (Praying my math is correct.) If drives were 10^16 UER, that number drops to 8% - much more desirable but still significant where data is concerned.
So my initial questions are:
- Where are the large SAS drives with 10^16?
- At what capacity size does 10^15 become statistically too unreliable?
- What is the fabrication cost difference between SATA and SAS? If SAS has many more benefits (wide/dual port, better error detection, etc) and the cost is insignificant, why hasn’t it been adopted for consumer systems?
- Why has it taken this long for SSDs to BEGIN to appear with SAS?
Thanks in advance.