Dell R720xd backplane question

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neb50

Member
Aug 28, 2018
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I have a LFF 12-bay Dell R720xd with the dual 2.5" rear drive bays. I saw another member replaced the 8-bay SFF front backplane in his R720 with the R730 SAS3 backplane with no issues and wondered if it was just because it is a "dumb" backplane vs the one in the xd with the built in expander chip.

Can I swap out the front and rear backplanes on the R720xd with the SAS3 ones out of a R730xd and replace the LSI9207 with a HBA330 to get SAS3 speeds for the drive bays? Or will the server reject it and either not power it up or refuse to boot?

Or could I just replace the rear 2-bay backplane with the R730xd one and run it off one of the HBA330 connectors and then use the other connector to the front backplane (knowing that I will only get 4 channels of SAS2 speed for the front 12 spinning drives) to get SAS3 performance out of the rear 2 bays?

Or is there another way to get a clean setup with SAS3 speeds on this server?
 

vanfawx

Active Member
Jan 4, 2015
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My understanding is the "xd" just means "extra drives". So to run 12 to 14 drives in the R720xd, there's a SAS expander in the backplane, and the rear two ports are just running off one of the ports on the expander, with an i2c extension to run the LED's.

The LFF R720 only has 8 drives, and doesn't offer the 2 rear ports, so no expander is needed, and the backplane is passive.

Because the rear ports are chained off of the front expander, if you were able to replace the rear bays, it would still be SAS2, because the expander is SAS2.

I'm also not sure what you mean about splitting the connection from a HBA330. The R720xd uses a mini mono card, and the backplane connector is on the motherboard, so there's no way to split it the way you're wanting. It's a x8 8087-ish connector.

Do you need SAS3 speeds for 12 LFF bays? Unfortunately I'm not sure what you're wanting is possible.
 

neb50

Member
Aug 28, 2018
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I am using a PCIe LSI-9207-8i card now to run the front/back backplanes so I am not using the mini mono card or the perc connector on the main board. I was wondering if the R730 sas3 front and rear backplanes would work with the R720. I do know that the mainboard does know if it is connected to a R720 or R720xd backplane and front panel and the system works differently based on what is connected to it. The R720 allows the use of the chipset SATA ports on the mainboard and the R720xd disables them (even when using the same mainboard, iDRAC, etc. with the only differences being the front panel and backplane.)

I am looking into possibly doing option 1 above: add in R730xd front and rear backplane and replace the LSI-9207 with a HBA330/LSI-9300. I am not sure if the mainboard/bios/iDRAC/etc. will work with this setup, but wanted to see if someone else has tried it.

Option 2: keep the front backplane the same, replace the rear backplane and HBA and connect one SAS connector off the card to the rear backplane and the second to the front backplane. The rear backplane will be using 2 (or 4 with dual port?) of the SAS ports and the other 4 would go to the front backplane and be shared by up to 12 drives at SAS2 speeds through the expander chip. Same issue as above with the mainboard/bios/iDRAC accepting the rear backplane not connected through the front expander and the second SAS port not connected to the front backplane.
 

neb50

Member
Aug 28, 2018
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I have currently got the server working with the rear 2 bays running off the HBA330 and the front bays running off the 9207-8i with no errors and SAS3 speeds on the rear bays. I am not using the mini mono integrated SAS controller and it is removed from the system.

Leave all the signal lines connected like normal on a R720xd with rear drive bays , remove the SAS cable that goes between the front and rear backplane and plug in SAS cable from HBA330 (9300-8i) using a SFF8643 to SFF8087 cable. The front to rear backplane I2C cable is needed to not have an error. The rear to MB I2C cable is needed to get the rear bays to work at all.

I may try to get a R730xd front and rear backplane to see if I can get the whole thing to run as SAS3, but will currently work with what I have now.
 
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neb50

Member
Aug 28, 2018
73
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I tried but ran into issues with the one of the power plugs being an 8 pin instead of the 6 pin and didn't have time when I was playing with it to create a new cable. Also, the front backplane has all of the front panel I/O go through it and I wasn't sure if all of those pinouts would be the same.

I have 2 of the front backplanes out of a 730xd 12 bay and the rear flex bay boards that I was going to try using. I am currently just using the 720 rear flex bay boards with the HBA330 for the SAS3 connectivity to the SAS3 SSD's that I have. Everything else is SATA so no gain for me currently to get it working.
 

Slothkitty

New Member
May 22, 2023
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Hoping to bring this back from the dead... sorry for resurecting, but i have been trying to do a similiar upgrade to my r720xd, but for a different reason. I replaced my h710p mini with a pcie h730p and wired the backplane to it with 8643-8087 cables, then for no reason at all i wired my flexbay directly to the h710p mini as opposed to the backplane. I mostly got this to work and found/imported foreign config and restored all my data. But idrac/osma show the h730p with a critical error reading backplane unknown. Not suprised, but everything else works, drives show negotiated 6gbps capable 12gbps. I realize thats because the backplane has a sas2 expander. The way i see it i have 3 options. 1. Leave everything as is and live with 6gb disks (not a huge issue) and ignore the error in osma. 2. Swap the backplane and figure out the power issue OP described, and hope osma can read the backplane without error. 3. Figure out the backplane error i have now, and just deal with 6gb disks. Im not sure where to begin with the backplane error, as the signal cables are all connected, and the flexbay shows no errors when wired back to the mini mono raid. I didnt try leaving it connected to the front backplane.. so im not sure if that would throw an error or not, but right now its all green. Any ideas here guys? I should state my original goal was to support 4kn disks that did not play nice with sgformat, and i did accomplish that, but im thinking if i can swap a working r730 backplane to get sas3 speeds that might be worth it.
 

Digital Spaceport

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Apr 17, 2022
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I'm double necroing this post. Did you get this to work? I can confirm I got the T630 backplanes to work in a T620 which was great for Toshiba SAS SSDs but overall. Indeed the iDrac doesnt show disks, but it doesnt halt the system at boot or anything tragic. Now I am itching to pull the trigger on the backplanes for the R720XD and see if I can beef up its backplane also.

Hoping to bring this back from the dead... sorry for resurecting, but i have been trying to do a similiar upgrade to my r720xd, but for a different reason. I replaced my h710p mini with a pcie h730p and wired the backplane to it with 8643-8087 cables, then for no reason at all i wired my flexbay directly to the h710p mini as opposed to the backplane. I mostly got this to work and found/imported foreign config and restored all my data. But idrac/osma show the h730p with a critical error reading backplane unknown. Not suprised, but everything else works, drives show negotiated 6gbps capable 12gbps. I realize thats because the backplane has a sas2 expander. The way i see it i have 3 options. 1. Leave everything as is and live with 6gb disks (not a huge issue) and ignore the error in osma. 2. Swap the backplane and figure out the power issue OP described, and hope osma can read the backplane without error. 3. Figure out the backplane error i have now, and just deal with 6gb disks. Im not sure where to begin with the backplane error, as the signal cables are all connected, and the flexbay shows no errors when wired back to the mini mono raid. I didnt try leaving it connected to the front backplane.. so im not sure if that would throw an error or not, but right now its all green. Any ideas here guys? I should state my original goal was to support 4kn disks that did not play nice with sgformat, and i did accomplish that, but im thinking if i can swap a working r730 backplane to get sas3 speeds that might be worth it.