Jump to content
bkastner

SAS Controller Questions

2 posts in this topic Last Reply

Recommended Posts

I currently have 3 SAS2LP controllers that tie into my Norco 4224 backplanes, but the new motherboard I have only has 3 x16 and 1 x1 PCIE slots. I am hoping to add a 10GB NIC, and possibly a transcoding video card down the road. I have bought a RES25V240 which I've seen I don't even need to mount in a PCIE slot which is kinda cool, but I am wondering what sort of throughput I am going to see if I use that. Given that I still need 1 HBA I am assuming I'd remove 2 SAS2LP, and have one with a direct connection to a backplane and the other to the RES24V240 with it's other 5 ports connecting to the other backplanes.

 

Essentially I want to try and understand the following:

1) Am I going to significantly impact performance with 5 backplanes going through the one card. I currently get around 95-98MB/s for Parity Checks and dont' know if this will really impact that, or if I have 8-10 people streaming off different disks am I going to bottleneck at all

2) Is there a significant difference between running 1 SAS2LP with 5 connections through the RES25V240 vs running 2 SAS2LP cards both feeding a connection into the RES25V240 card and only using 4 connections from that to backplanes

3) Given that the backplanes are all 6GB SAS, is there any value in buying a 12GB SAS controller with 6 ports and run SFF-8643 to SFF-8087 converting cables? I've had one vendor tell me this could cause issues (i.e. frying backplanes), but I dont' know if that's true, or if I'd see any improved performance vs the SAS Expander... If so, this would also potentially set me up if I was to replace the case down the road as I could get one with 12GB SAS (though these are really expensive)

4) Would I even notice much difference between 6GB SAS and 12GB SAS with all WD Red drives? I know this gets into a throughput question, and I've seen some comments on other threads, but I'm still not clear on if there is a significant gain by going to 12GB SAS (enough to justify a $500 card and $1200-$1500 case down the road)

 

Any input or thoughts would be appreciated.

Share this post


Link to post

IIRC the SAS2LP doesn't perform very well with an expander, they are also not recommended for Unraid for a long time now, the expander works very well with an LSI HBA, you can see some performance numbers here.

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.