Storage Spaces Direct on R6525

Question

I have PowerEdge R6525 servers with the NVMe backplane and the H775N controller (figure 57 in the installation and service manual), on which I wanted to install Storage Spaces Direct. Unfortunately unknown to me, but to the forums (Solved: Dell R730xd with H730 Mini and Non-RAID/HBA mode and W2016 Storage Spaces Direct - Dell Community), having the SSDs configured as "non-raid" still exposes them as RAID devices to the OS. In another thread, someone suggested to replace the controller with an HBA330, which I think is not intended for the R6525.

I am contemplating my options now: I have space for a Broadcom HBA 9500-16i, which should solve the problem, but I don't know which cables I would use for that, because I would require for x4 connectors, if I got that right. I actually would prefer a Dell solution, but I wasn't able to find a card I am sure will work with the NVMe drives as JBOF.

Addiitionally, I saw that there are configurations the connect the backplane directly to the motherboard (SL5 and SL6 in Fig. 54 in the installation and service manual) and was wondering if that would work for a machine initially equipped with the H775N. If that works at all, I need four cables, which I was not able to figure out yet.

Does anyone know which of the ideas works and what the part numbers for that are?

Thanks in advance,
Christoph

DELL-Chris H · Answer

Muellech,

We actually did a test on the R6525 with Storage Spaces Direct, which can be found here. It covers the hardware used and other configuration data.
To see the hardware used you can select System Configuration Info on the menu to the left.

Let me know if this helps.

DELL-Shine K · Answer

Changing backplane configuration from one config to another config is not recommended as it may result in configuration issues. Can you provide details on heatsink you have on the server as NVMe cable part# could vary based on what heatsink you have? Did you have standard heatsink or L Shaped heatsink. L shaped heatsink required if you have CPU which is more than 180W

muellech · Answer

I would also prefer a non-intrusive solution, but I need to make it work somehow ... We have the coolers for less than 180 W.

muellech · Answer

I will have a look at it. It seems to be at least similar in that it uses NVMe drives. However, the one thing that seems not mentioned, and which is probably the most important one, is whether you have used the H755N front controller.

Dell-Martin S · Answer

Please provide feedback if you have finished all the steps.   Regards Martin

muellech · Answer

I have followed the instructions to the extent it was possible (we have e.g. Mellanox NICs, no Broadcom) until step 1. b of section "Using one node to create the Storage Spaces Direct cluster storage". Here, the cluster validation fails, because the NVMe disks are recognised as RAID:

This is basically the exact problem that the OP of the link I initially posted described: Even if you configure the drives as "NonRAID", they still show up as "RAID" in Windows.

I honestly do not see how I could configure that differently and the instructions did not mention anything in the BIOS except for the NIC.

muellech · Answer

@Dell-Martin S: are there any other settings regarding the PERC in the BIOS that might be relevant and that are not listed in the guide? The "NonRAID Disk" option seems the closest fit I need to me, but it still show up as RAID in software.

@DELL-Shine K: can you provide me with the part numbers? I think the PERC 755N is actually causing this issue and I guess your demo system had a different configuration, which is unfortunately not mentioned in detail.

muellech · Answer

Hi Chris,

In the meantime, I had the time to check out all possible configurations of the H755N, which are basically "non-raid disk" and "raid 0" on single disks. In both cases, the effect is that the disks are not eligible for S2D, because Get-PhysicalDisk lists the bus type as "RAID". Do you have any additional information on how the NVMe drives were connected in your test?

Thanks in advance,
Christoph

DELL-Chris H · Answer

Unfortunately I don't, I will research the issue further and see if I can find anything. You may also want to call in so they can analyze the system and configuration as well.   Let me know.

muellech · Answer

I actually noticed that on System configuration information | Boost SQL Server OLTP performance with PowerEdge R6525 servers powered by 3rd Gen AMD EPYC 7543 processors | Dell Technologies Info Hub, there is a description of the hardware, which lists the PERC H345 as controller. Looking at the spec sheet dellemc-poweredge-raid-controller-h345-datasheet.pdf, I think the key feature is that "Non-RAID" is described as "JBOD Mode", which is not the case for all other PERCs.

I now see two problems:

1. Can I replace my H755 with a H345, specifically will the H345 come with the cabling necessary to make this work? I see four x8 connectors on the backplane, so I would need to have two quite long Y cables from x8 to x8.

2. At least in the German store, I cannot see the H345, only newer ones that do not have the "JBOD mode". Can I still get these controllers from Dell?

DELL-Chris H · Answer

Muellech,

I actually didn't catch the controller difference, so nice catch. As far as your questions, first swapping hardware controllers out there shouldn't be a change in cable. As far as the part itself, you would need part number 405-AAWF, seen here.

Let me know if this helps.

muellech · Answer

Unfortunately, I can only see the H355 in my German Dell Premier account, but I will ask our sales rep whether she can quote the H345. I don't want to try the H355, becuase the manual says it does not support NVMe drives, which is baffling as your white paper says they used the older H345 and NVMe disks.

PowerEdge HDD/SCSI/RAID

Storage Spaces Direct on R6525

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