7200 RPM SAS Drives - Worth It?

[Mirfster]

Are they even worth it? Was doing some "window shopping" and noticed some 7200 RPM SAS drives which were ~$25.00 more. So it got me wondering...

Would it be advisable to consider paying the extra $25.00?

Examples: 4TB SATA vs 4TB SAS

 

[Bidule0hm]

No :)

 

[Mirfster]

No :)

Well I must say you make quite the convincing argument. :P

TBH, I normally never buy new so I can comparing them on eBay. Pricing actually is pretty much even; with SATA at times actually more expensive..

SAS I am looking at
SATA I am looking at

How about now? Might actually be "safer" to get a used drive that has a longer shelf life and better bit error rate. (Notice how I am trying to talk myself into this? ;) )

What about SAS supposedly having a benefits such as:

• Hugh difference in "bit error rate (BER)" x 10 of SATA Drives
  
• SAS disks/controller pairs also have a multitude of additional commands that control the disks and that make SAS a more efficient choice than SATA
  
• SAS includes multiple full-duplex data channels, which provides for faster throughout of data
• Referenced from http://www.techrepublic.com/blog/data-center/how-sas-near-line-nl-sas-and-sata-disks-compare/

 

[Bidule0hm]

Yeah okay, maybe I need to be a bit more verbose... :D

I was talking for a home server and comparing NAS SATA drives with SAS drives (so the lower RPM for NAS drives is equal to a bit less perf but also less power draw and less cooling needed) but now I see you want to compare SATA and SAS all other things being more or less equal, so yeah, not the same thing :)

 

[traderjay]

But can we safely say that with ZFS, the difference in bit error rate between SAS and SATA is negligible since it has bit rot protection. But it is a different story when it comes to pool recovery?

 

[Mirfster]

Well considering that SAS has more calls and is supposedly natively better at avoiding/handling error correction would that naturally make it the better drive (regardless of OS, Appliance or Platform)?

 

[Mirfster]

Going to find out first hand... Purchased 13 x HGST HUS724040ALS640 4TB Drives... Will see how this goes once they arrive.

 

[AuBird]

How did it go? It's been 30 days. And will you update your avatar with a picture of your new hard drives in your rig?

 

[Mlovelace]

Really the big advantage to nearline SAS drives is that they are dual port, so you can attach the drive to redundant controllers or HA heads.

 

[Mirfster]

Drives are nice, run a little hotter than normal SATA. On vacation right now though so will post more when I get back.

These are full SAS, not Near line so are full Duplex as well. Also SMART results are totally different than what one would see for SATA.

Drives were practically new with very low hours and still showed warranty for 3 more years.

 

[Mlovelace]

These are full SAS, not Near line so are full Duplex as well. Also SMART results are totally different than what one would see for SATA.

Nearline are "full SAS" with a rotational speed of 7800 rpm or less and typically larger capacity. You might also see them referred to as midline.
Here's a decent write up. https://www.ibm.com/developerworks/...s_when_is_a_sas_drive_not_a_sas_drive?lang=en

 

[Mirfster]

Okay, that makes sense. So I looked up the spec sheet from HGST and they are as you stated. Mainly a SATA with a SAS interface. Slightly higher sustained transfer rate. Got them a little cheaper from the seller since I purchased 13 of them.

Still waiting for SSDs to drop in price so these will be good for a JBOD for now.

Thanks for the clarification.