Spanning on Dell T7910 SAS controller (CentOS 7)

Superpos

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Jun 9, 2020
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I just bought a Dell T7910 and I'm thinking about setting up a scratch work space by adding four SATA drives internally to the integrated LSI SAS 3008 controller on the motherboard. Right now I'm thinking I don't want to use any RAID modes on the controller and instead probably go with a JBOD/spanning type of setup.

Here's a great tutorial that makes this look easy using mergerFS. But before committing to buying any drives:

Do I need to flash the onboard SAS controller to IT mode beforehand? I found a good youtube tutorial for exactly this by Art Of Server, but it still looks a little involved.

My understanding is that if I set up any volume configuration in software then it's best to use IT mode so that the underlying hardware RAID controller isn't clashing with the software. But I'm really new to this so I'm not sure. If this isn't easy I can just go with one of the RAID modes on the card. RAID 6 or 10 are great, but I'm just trying to maximize storage size and not redundancy.

Thanks for any insight!
 

Superpos

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Jun 9, 2020
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Update on this: I decided to just buy some SAS drives and I will make a RAID 10 with the internal controller. It feels a little risky for someone inexperienced to be flashing the controller when it's integrated with the motherboard.
 

Prof_G

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Jan 16, 2020
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I did the flash to IT its as easy as it looks and the Guy from Art Of Server emailed me back he would answer questions if you have them.. Sata or Sas it doesn't care what is connected. What's getting harder to find is the 4x2.5 expansion bay kit that Dell made for these. If you need help with anything I'll try and help.
 

Superpos

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Jun 9, 2020
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Appreciate the reply, I'll re-watch the Art of Server youtube video. Do you have any thoughts on MergerFS? It looks pretty intuitive and that would be the reason for flashing.

My 4x3.5" SAS drives arrived and I still have not acted on either flashing the controller or going with on-board RAID 10. This storage is just a working space in addition to my old NAS which these days is a little too slow to work off. My future goal is buying a few R7910s and making a small high speed networked storage cluster like MinIO.

Re: the 4x2.5" bay, I did see the expansion kits readily available on eBay but they're a bit pricey. I deduced that an IcyDock kit would work just as well.
I originally was considering adding 8x2.5" disks, maybe SATA SSDs but I decided to pass on that for now because it's still not that affordable especially since NVMe is coming up. Sabrent et al.
 

Prof_G

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Jan 16, 2020
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MergerFS/FreeNas/Unraid/OMV they all do about the same thing. Go with what's comfortable. Nothing wrong with the onboard raid 10 and if do flash to IT mode you can flash back if you want. If you're not in a hurry try out both. But may require you to re-install OS.

If you need the computer to be up and running run the raid 10 would be the way to go.

One thing I did do is get this if you don't care about a DVD drive.

2.5" DVD hard drive cage. I used that along with the block off cover and used the plastic screws to mount it. I have that as my boot drive. Its a Standard SATA connection. Power/Sata cable should be there if the guy you bought it from didn't take them out. This method you may not have to scrap the whole installation just flash/Format the larger block of HDDs IT/IR and your storage raid array is not occupied by part of your OS system.

There is 2 sata connections at the bottom of the board. One is used by the DVD rom cable. so if you really need to add more storage that is the last little bit of storage before moving to a PCI NVMe card holder.

I would say that while you can run all these systems on here the form factor of the 3008 4 x3.5 plus the 4x2.5 is more of desktop just adding drives as you go the 7910 is probably better on the stock dell IR firmware. With the stock IR firmware I don't recall what it does if you do nothing to the drives I think it just passes the options to the Os of 0,1,or 10 Will probably wipe my system and go back to the IR firmware. Doesn't make much of a difference right now as I'm just running windows for it.

You can put the IcyDock in but mounting points might be a bit trouble sum.

I have owned mine for 5 years now and has served me well.

Only thing I'm not hot on is the two PCI Card slots on top/side of the processor. Both are 3x16 but the could have made the spacing for a 3 slot PCIe up there and done removable handle/or hinge. PCI slots on top makes moving this motherboard out of the case impossible.
 
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Superpos

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Jun 9, 2020
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Thanks for your additional notes, good to hear of your experience with the machine. Overall I'm pretty happy with my purchase. I'm probably going to be installing the OS on an NVMe stick in a 4x slot so trying a few things out with the SAS drives would not be a problem.

I do like the idea of the SSD in the DVD drive cage, I did that in a 17" MacBook Pro back in the day. But I'm leaning more to some kind of NVMe network clustered storage in the mid to near future so it seems better to not have the boot drive as a bottleneck. I'm just seeing this 4x SAS combo as a temporary working space for everything on my NAS until I can establish something faster. I need to work with ~10TB off the NAS so I need some decent working space.
 
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