SAS Expander Speed Concerns


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Hi everyone! First post!

I'm new to Unraid and I've been planning my NAS build for some time. I'm planning to use the GA-7PESH2 mobo with onboard LSI SAS2008 alongside the HP expander. I was planning to dual channel it into the mobo and connect most of my HDDs to the expander.... Then I read that the expander will only negotiate to SATA II speeds at 3GB/s even if the drives are SATA III capable.

Should this be cause for concern?

I’m planning to use 12 10TB 5400RPM WD Red drives over SATA for my data array and 2 1TB SSDs as my cache array. The cache array will be directly connected to my MOBO over SATA III to ensure the fastest transfer rates possible.

Should I be worried about transfer rates if most/all of my data drives are only connecting at 3GB/s?


I did check this post: 
 


Unfortunately there wasn’t much help there. And I’ve been reading through a bunch of other threads here trying to verify my access speeds, but I’m not quite understanding the math.

Let me also mention that I'm planning to link this to my main server over a 10GbE link so I can stream 4k content off of it. Which is why the speed is of such great concern to me. 

Can any one assist? 

Edited by DeathByDentures
Incorrect drive speed stated for WD Reds - corrected.
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28 minutes ago, DeathByDentures said:

Unfortunately there wasn’t much help there.

Dual Link on Dell H310 (2400MB/s*)

12 x 182.5MB/s

16 x 140MB/s

20 x 110MB/s

24 x 95MB/s

 

What's unclear about this?

 

29 minutes ago, DeathByDentures said:

I’m planning to use 12 10TB 7200rpm WD Red drives

WD Red are 5400rpm, not 7200rpm, 180MB/s is a little below their max speed, so it will bottleneck a little in the beginning of a parity check, disk rebuild, but not by much.

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8 minutes ago, DeathByDentures said:

It's unclear as no listing for this Mobo states that the Dell H310 is the controller for the onboard sas.

H310 uses a SAS2008 controller, like mentioned on the thread, all SAS2008 based controllers have the same performance (assuming using the LSI IT firmware).

 

9 minutes ago, DeathByDentures said:

And I posted this as a comment on a 1 year old thread. I don't consider that crossposting. 

I do, other users might see that one first and reply there instead, resulting in redudant information.

 

 

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