Ok, a little nerdy but we ordered some SAS drives and I was surprised that we got the V3 older Constellations. It is incredibly hard to figure out the right drives, but in looking at the Seagate data sheet I can see why, there are so many different models.
And a search for Seagate Enterprise Capacity, gives you
both V3 and V4 drives. Look for the ending digit in the model number, a 3 means V3 and a 4 means V4. The first digits are the capacity:
So ST6000NM0024 means:
- ST – SeagaTe
- 6000 – The capacity in gigabytes, so this is 6TB drive
- NM – Not quite sure but it seems to be there
- 002 – The submodes
- 4 – the generation, so Constellations are 3 and the latest Enterprise Capacity are 4
The submodels are complicated but for SATA 6Gb drives we have. Note these are SATA drives and more expensive, but with 10^15 error (so 10x more reliable than “normal” drives):
- 000 – Standard model with 4K native sector
- 002 – Standard with 512 block emulation
- 006 – Secure erase (which means it will erase quickly good for enterprises that don’t want to erase data)
- 004 – SED in 512 emulation mode
- 009 – SED FIPS (eg federal approved) in 4K native
- 008 – SED FIPS in 512 emulation
- 012 – PowerBalance 512 emulation (means less power usage)
Then for 12Gbps SAS drives (really fast) and needs great controllers:
- 001 – Standard 4K native block
- 003 – Standard 512 emulation
- 007 – SED 4K
- 005 – SED 512
- 011 – SED FIPS 4K
- 010 – SED FIPS 512
Finally for 6Gbps SAS drives (more typical in server machines) these are not V4 drives, so they are using the older technology which explains why we got the wrong drives when we tried to order them. Now a 7200 rpm drive can’t even use all that bandwidth (you need SSDs to do that), so it is more for compatibility than anything else. As a reminder, a 6Gbps SAS drive has about 500MBps maximum which is plenty for hard drives, but SSDs can get to twice that quite easily. As another aside the HGST Deskstar NAS for SATA is a good buy given it’s decent performance (7200 rpm) and 10^15 reliability and low price
As an aside, the Supermicro X10 line has eight 12Gbps SAS drives but the Norcotek 4220 only supports 6Gbps drives, so to use the 12G SAS, you would need another enclosure but these are really expensive at $2K for a Norco DS-24H drive chassis or you need to get a non-hotswappable drive system that would then be compatible like the Norco.
Storagereview.com did a test with the 12Gbps SAS on a 6Gbps controller, so that seems to work.
