Onboard SATA or 6GB/s LSI board?


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Beware Marvel controllers and unRAID v6 however.  You might be one of the lucky ones where you won't have any problems with Marvel controllers but you might not.  I say this because my ASRock - EP2C602-4L/D16 has 14 SATA ports but 4 of them are on a Marvel MB controller and I had dropped drives all the time.  Luckily I was passing it through to a VM so I never had problems with dropped drives from my array.  But it was annoying having to reboot the server every time it happened in order to get access to the drives in the VM.

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3 hours ago, BobPhoenix said:

Beware Marvel controllers and unRAID v6 however.  You might be one of the lucky ones where you won't have any problems with Marvel controllers but you might not.  I say this because my ASRock - EP2C602-4L/D16 has 14 SATA ports but 4 of them are on a Marvel MB controller and I had dropped drives all the time.  Luckily I was passing it through to a VM so I never had problems with dropped drives from my array.  But it was annoying having to reboot the server every time it happened in order to get access to the drives in the VM.

Yep, I have an AOC-SAS2LP-MV8 in my system now.  I don't have problems dropping drive, but ever since upgrading to 6.2, my system only runs for a couple days, then over the course of a few hours, the system crumbles.  I loose the GUI, then I loose FTP, then I loose SSH and finally the console locks up.  I've ordered LSI controllers which come tomorrow and I'm replacing them.  My query above was for my next system.  Thinking about what the best platform should be for an unRaid server.  Would more threads be better (i.e. 2 CPU's) or whatever...  Just starting to think about that.  I've upgraded my main workstation to a Z370n i7-8700k and so I've been looking at main boards.  ASrock have a lot of boards with a whole bunch of ports.  Ergo my question.

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On 12/1/2017 at 6:07 PM, BobPhoenix said:

Beware Marvel controllers and unRAID v6 however.  You might be one of the lucky ones where you won't have any problems with Marvel controllers but you might not.  I say this because my ASRock - EP2C602-4L/D16 has 14 SATA ports but 4 of them are on a Marvel MB controller and I had dropped drives all the time.  Luckily I was passing it through to a VM so I never had problems with dropped drives from my array.  But it was annoying having to reboot the server every time it happened in order to get access to the drives in the VM.

@BobPhoenix - so you say that extend to motherboards with Marvel controllers as well?  I'm still having system degradation with this system.  The LSI swap works fine, but parity is VERY slow.  I have 8 drives on the motherboard sata ports.  I know at least 4 of them are a marvel controller.  I'm going to pull everything off the motherboard and move it to a second LSI card as soon as I get the cables in.  I'll post results...

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11 hours ago, jeffreywhunter said:

@BobPhoenix - so you say that extend to motherboards with Marvel controllers as well?  I'm still having system degradation with this system.  The LSI swap works fine, but parity is VERY slow.  I have 8 drives on the motherboard sata ports.  I know at least 4 of them are a marvel controller.  I'm going to pull everything off the motherboard and move it to a second LSI card as soon as I get the cables in.  I'll post results...

Correct.  My ASRock  - EP2C602-4L/D16 has a Marvel 4 SATA port controller that I do not use at all.  The other 10 SATA ports are from the Intel chips and work fine both for the array and passed through to VMs.  I would do like you said and transfer all drives to LSI controllers and have nothing connected to Marvel controllers.  My guess (and it is a guess since some people do not have problems with Marvel controllers) is that will fix your access problems.  It is suggested it is a combination of drive manufacturer and SATA interface version on the drive that causes it.  I haven't found a combination that works for me except switching controllers to LSI.  If I had more time to experiment I might be able to come up with something else but swapping controllers is just so much easier.

Edited by BobPhoenix
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Update.  Moved everything from the motherboard to the two LSI 9207-8i controllers.  Performance of parity check is better, array at 286MB/s, about 26MB/s for each drive.

 

Getting back to the question regarding bottlenecks.  Do the motherboard SATA ports share lanes with the PCIe?  In other words, would it make better sense to use the non-marvell controller ports on my motherboard vs having all the drives on the LSI cards?

 

Which also begs a discussion on Parity and Cache placement.  Assuming the answer to the above is the motherboard SATA does not share lanes with the PCIe, does it make a performance difference to have the CACHE drive on the motherboard vs one of the LSI's?  And thus the same question for the Parity drives?  Should I put those on the motherboard vs the LSI?  Just trying to optimize performance by eliminating bottlenecks.  I'm pretty sure the answer would be to move the Parity and CACHE to the non-marvell motherboard ports.  Am I right?  No difference?

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Just now, jeffreywhunter said:

Do the motherboard SATA ports share lanes with the PCIe?

 

Assuming your signature is correct both top x16 slots are CPU slots, if both are occupied they become x8 slots but they are not shared with anything else, the bottom x16 slot is only x4 electrically and shares the DMI with the onboard SATA, plus NIC, USB ports, etc.

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1 hour ago, johnnie.black said:

 

Assuming your signature is correct both top x16 slots are CPU slots, if both are occupied they become x8 slots but they are not shared with anything else, the bottom x16 slot is only x4 electrically and shares the DMI with the onboard SATA, plus NIC, USB ports, etc.

 

Thanks Johnnie.  I have the LSI 9207-8i controllers in the top two slots.  Based on what you said then, would it make sense to keep the LSI controllers for data drives only and put the Parity and cache drives on the motherboard SATA?  That should improve total system throughput.  Correct?

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Getting back to your initial question about best controller for drives, thought I would try to address. 

 

First, if your motherboard or add-on controller use Marvel chipsets, disable that controller in BIOS for motherboard controller (if possible) / remove the HBA. Don't risk using them.

 

Generally speaking, normal motherboard (chipset provided) sata ports are the best. Only situation I'd advise using something else first is if they are not fast enough for an SSD (old motherboard). They tend to be the fastest, least problematic ports.

 

With add on controllers, there are a lot of variables.

 

1. Some (especially prior generation ones) don't support trim, which is important for SSDs. LSI SAS9201s have this issue for example. Work great for spinners, but use MB or newer controller for SSDs.

 

2. Sata spec / single port performance needs to be fast enough. Not a problem for spinners with sata2+. SSDs need sata 3.

 

3. Bandwidth constraint. This it's a tricky one as it involves the PCIe version number (1.x, 2.x, 3.x) of the HBA and slot (slowest rules), the usable (electronic) slot width (x1, x4, x8, x16), and the number of drives that will be in simultaneous use. Remember PCIe 2.0 at x4 would support 8 spinners almost exactly.

 

4. Other conflicts. As Johnnie mentioned, with shared DMI and resources. I would not know how to calculate, but if you are running close to maxing out, could come into play. Benchmarking might be only way to determine how these shared resources would impact performance.

 

In your case, the new LSI controllers are excellent. Doubt you'd have any performance bottlenecks with spinners, but might have bandwidth constraints with several SSDs depending on the slot / drives in parallel use. But I'd still favor the motherboard slots.

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