Intel RES2SV240 SAS 2 Expander Question

[crowdx42]

Hi al,

 so I picked up the Intel RES2SV240 SAS 2 Expander card on eBay. My intent being to replace my two Dell Perc 310 cards which are flashed to IT mode. I received the card today but I am not seeing any confiog screen for the card on boot and none of the drives are being detected that are attached to it on my test machine.

Will this card work without working in RAID mode? Is there something I am missing with setting it up?
Help!!
Patrick

[tjb_altf4]

You still need one HBA (e.g. H310) connected to the expander. for the expander to work.

The expander allows you to run more disks off the HBA by sharing the bandwidth.

[crowdx42]

So I would need a SAS cable connecting between the 310 and the expander OR do they connect over the pci express bus?

[crowdx42]

So I looked this up and it does seem they connect via cable. My last question is, on my motherboard I have a 16x PCIe and 2 8x PCIe slots. Which slot should the expander go into? I think the 8x share with each other and so if both 8x slots were used they would drop to 4x.
So, should the 310 be in the fastest slot or the expander? Also, is there a performance hit using the expander vs 2 310s? Currently I have 16 drives on the 310s and another 4 drives on the motherboards SATA ports.
Patrick

[tjb_altf4]

2 hours ago, crowdx42 said:

So I would need a SAS cable connecting between the 310 and the expander OR do they connect over the pci express bus?

Should be a sff-8087 to sff-8087 cable, but do check your own card's connectors.

You can run a single cable, but if you run two (from a single HBA only) you'll increase the overall bandwidth available to the expander.

 

19 minutes ago, crowdx42 said:

So I looked this up and it does seem they connect via cable. My last question is, on my motherboard I have a 16x PCIe and 2 8x PCIe slots. Which slot should the expander go into? I think the 8x share with each other and so if both 8x slots were used they would drop to 4x.
So, should the 310 be in the fastest slot or the expander? Also, is there a performance hit using the expander vs 2 310s? Currently I have 16 drives on the 310s and another 4 drives on the motherboards SATA ports.
Patrick

Expander uses pcie for power only (no data).

To keep those slots free for other devices you can use any slot including a 1x slot, or none at all and use molex power connection instead.

 

HBA + Expander will have less bandwidth than 2x HBA, but that is a limit you probably won't notice unless you are maxing out drive connections.

A forum member JorgeB has a great benchmarking thread which can give you an idea on speeds to expect.

 

Typically the best performance scenario is to put parity and any sata ssds on the motherboard sata ports, so these will always run at maximum capacity.

 

[crowdx42]

Excellent info. I have already ordered two mini SAS cables and so I should be able to utilize the most out of the 310 card. Being that I can use the 310 in the x16 slot, I would think I should see a performance increase as I currently can only use a single 310 in the x16 and the other is in the x8 slot.
I have noticed during drive rebuilds that speed slows down for the last few hours of the rebuild. I wonder is it the drive that is being rebuilt that causes this slow down or is it the bandwidth for the parity drive.
Again, thanks for the help.
Patrick

[ChatNoir]

2 hours ago, crowdx42 said:

I have noticed during drive rebuilds that speed slows down for the last few hours of the rebuild.

Unless it is a large step down in speed, this is probably because the drives always slow down while reading the entire surface.

the outer sectors are mechanically faster than the inner ones.

[crowdx42]

Well I dug up a cable and connected the Expander to the Dell 310 card. It looks like it is working fine, all drives that I have attached to the card are showing up. Is there anything else I should be watching out for? I know in a previous configuration with an LSI HBA card I had, I would get errors on the parity checks, this went away when I moved to the 310. Is there anything like this to watch for OR does the expander just simply receive data from the drive and forward to the 310 with no data manipulation occuring and so acts more like a splitter than an actual card processing data?
Not sure if I am being clear here
Patrick

[crowdx42]

18 hours ago, tjb_altf4 said:

Should be a sff-8087 to sff-8087 cable, but do check your own card's connectors.

You can run a single cable, but if you run two (from a single HBA only) you'll increase the overall bandwidth available to the expander.

 

Expander uses pcie for power only (no data).

To keep those slots free for other devices you can use any slot including a 1x slot, or none at all and use molex power connection instead.

 

HBA + Expander will have less bandwidth than 2x HBA, but that is a limit you probably won't notice unless you are maxing out drive connections.

A forum member JorgeB has a great benchmarking thread which can give you an idea on speeds to expect.

 

Typically the best performance scenario is to put parity and any sata ssds on the motherboard sata ports, so these will always run at maximum capacity.

 

So I have been doing a little bit of testing on peformance and I am getting strange numbers. If I plug in all 16 drives in a test machine (8th x 4 and the rest 4tb by Western Digital and Hitachi), the parity build dives to about 30mb/s . With only the 8tb drives I am getting 185mb/s and with WD 4tb drives alone I am getting 175mb. I have also tried the parity drive on the MB Sata port and also on the SAS expander and it does not seem to make a great deal of difference.
I also notice that the cpu is spiking a lot to 100% (i3  G4400  @ 3.3ghz. I wonder if the cpu could be bottlenecking the system when I try to to a parity build with all drives attached? My other thought is that one of the drives might also have issues and causing read issues, unlikely, but they are not the newest of drives.
From the linked data above I would think 16 drives attached to the SAS expander should not be an issue at all for it, I have it connected via 2 mini SAS cables which I believe should give the best performance. 
Thoughts?