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PCIe Gen3 x8 to 2x SFF-8643 (uses a PLX PEX8718 switch)
PCIe Gen3 x8 to 2x SFF-8643 (uses a PLX PEX8718 switch)
Supermicro AOC-SLG3-2E4 - $25
- Thread starter UhClem
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I'm having a difficult time understanding the application for this in the modern era, outside of enterprise reliability. Any specific benefits the PLX switch provides to nvme pass-through, for the 6w it uses? (EDIT: Ah you can eject drives, that's tempting for a hot-swap application).
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I'm running one of those in my workstation for a icydock dual NVMe/M.2 bay. It just works, never had any issues...
And what exactly about them? Its simply a pcie-switch so you can actually use an x8 slot for 2x x4 NVMe on crappy desktop boards that don't allow bifurcation. They 'just work', so not sure what FUD you heard...
Mainly it's that it will connect two devices to an x8 slot even if your motherboard doesn't support bifurcation, but it will also let you run both in an x4 slot, with some bandwidth limitations.
If you are interested in those PCIe switch cards, then this might also spark your interest:
Based on an Renesas/IDT 32-lane PCIe 3.0 switch:
Also available in Germany, for the fellow Germans. Here (DE) you can get it for as low as 17,90 EUR, from Quant Electronic.
Have fun!
Sun Oracle 8-Port PCIe Switch Controller Card Low Profile 7064634 7096186 | eBay
We can?t give you a price quote. item not as described?. Received wrong item?. Item is defective?. and that is not the correct option, You will be reported. We will be happy to resolve the issue and work out a solution with you.
www.ebay.com
Based on an Renesas/IDT 32-lane PCIe 3.0 switch:
Also available in Germany, for the fellow Germans. Here (DE) you can get it for as low as 17,90 EUR, from Quant Electronic.
Have fun!
Oh you know what I think I am confusing this with something else sorry. There is something similar that lets you try and use less lanes for more devices right? Switch vs retimer? I heard those in particular while they let you use more devices/drives/whatever take a performance hit to do.
I could also just be straight up wrong. That's normal.
The reasons you'd use these are:
1. Hotplug - your BIOS still needs support for hotplug events if you want it to work properly, and needs to reserve enough resources, but this will get hotplug working even if you don't have any slots with hotplug controllers.
2. Does not require bifurcation.
I haven't been able to get LED management working on these unfortunately. The supporting documentation explicitly says that it's supported, but it must only be on a narrow range of motherboards or backplanes.
I also have an issue on one of my systems where, when I use two of these adapters, the first adapter behaves normally, but once I start connecting drives to the second one, it causes some weird SMBus issues which causes the IPMI to sometimes report garbage values for completely unrelated things (like CPU temperature).
Overall, still very hard to beat in terms of value for a setup that won't bottleneck drives.
1. Hotplug - your BIOS still needs support for hotplug events if you want it to work properly, and needs to reserve enough resources, but this will get hotplug working even if you don't have any slots with hotplug controllers.
2. Does not require bifurcation.
I haven't been able to get LED management working on these unfortunately. The supporting documentation explicitly says that it's supported, but it must only be on a narrow range of motherboards or backplanes.
I also have an issue on one of my systems where, when I use two of these adapters, the first adapter behaves normally, but once I start connecting drives to the second one, it causes some weird SMBus issues which causes the IPMI to sometimes report garbage values for completely unrelated things (like CPU temperature).
Overall, still very hard to beat in terms of value for a setup that won't bottleneck drives.
Have you been able to get it working? I couldn't ever get it to work in a commodity system.If you are interested in those PCIe switch cards, then this might also spark your interest:
Sun Oracle 8-Port PCIe Switch Controller Card Low Profile 7064634 7096186 | eBay
We can?t give you a price quote. item not as described?. Received wrong item?. Item is defective?. and that is not the correct option, You will be reported. We will be happy to resolve the issue and work out a solution with you.www.ebay.com
At least the M.2 carriers from supermicro and some NICs have jumpers to set the SMBus address to avoid such weird behaviour due to overlapping; haven't checked the documentation for this card though, but I suspect you can set the address on those too.
Supermicro support is usually very quick and helpful, so I'd just send them a mail regarding this problem.
Any idea which pinout these use?If you are interested in those PCIe switch cards, then this might also spark your interest:
Sun Oracle 8-Port PCIe Switch Controller Card Low Profile 7064634 7096186 | eBay
We can?t give you a price quote. item not as described?. Received wrong item?. Item is defective?. and that is not the correct option, You will be reported. We will be happy to resolve the issue and work out a solution with you.www.ebay.com
Based on an Renesas/IDT 32-lane PCIe 3.0 switch:
Also available in Germany, for the fellow Germans. Here (DE) you can get it for as low as 17,90 EUR, from Quant Electronic.
Have fun!
Looks like these have been discussed here before: https://forums.servethehome.com/index.php?threads/sun-oracle-7096186-pcie-switch-adapter-plx.29392/
Same Q for the supermicro ones actually
Another use is if you wanted to you could hang 2 NVMe off a 4x chipset slot with that supermicro card, very useful for the Optane drives that pop up assuming the PLX doesn't kill the latency too much
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"Performance hit" is usually vastly over stated. In most cases you are not hitting max speed of the drive anyways. I'd worry more about latency hit depending on the exact PLX chip or worse bad blocking behavior when more than one device is communicating.
It's quite funny how many poeple just use the term "PLX" (a company, that today is owned by Broadcom) synonymously with "PCIe-switch", although there are numerous other IC manufacturers out there.
And BTW, this is just a switch card, without any additional logic. So, as long as you have the right cabling and/or adapters, it will do what it's intended to do. Switch PCIe-packets, so that you can use a phyisically limited number of PCIe lanes for devices, that would otherwise require a higher number of lanes (not necessarily exactly like that everytime, but this is the most common use-case).
Keep in mind though, that not each and every system will "like" a PCIe switch. Sometimes there are resource issues, signalling issues etc. .
And BTW, this is just a switch card, without any additional logic. So, as long as you have the right cabling and/or adapters, it will do what it's intended to do. Switch PCIe-packets, so that you can use a phyisically limited number of PCIe lanes for devices, that would otherwise require a higher number of lanes (not necessarily exactly like that everytime, but this is the most common use-case).
Keep in mind though, that not each and every system will "like" a PCIe switch. Sometimes there are resource issues, signalling issues etc. .
I have a bunch of these cards in use. I recently bought one from ebay that was not working properly.
Host device was showing up on PCIe bus but no devices.
I accidentally touched the large 'Vitec' power chip on the board and it was scalding hot. I yanked the cord.
Then I started checking the other boards I have and found that under normal load this "Vitec" chip runs hot.
So I put some heatsinks on them for good time sake.
I really like the cards for legacy systems like X9DRX. They do have a heat component and thusly a power draw.
Host device was showing up on PCIe bus but no devices.
I accidentally touched the large 'Vitec' power chip on the board and it was scalding hot. I yanked the cord.
Then I started checking the other boards I have and found that under normal load this "Vitec" chip runs hot.
So I put some heatsinks on them for good time sake.
I really like the cards for legacy systems like X9DRX. They do have a heat component and thusly a power draw.
I had no luck on FreeBSD with those Oracle cards...
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It may be "just a switch card", but they can vary in terms of things like hotplug, backplane management, and SMBus support. Some of the cheap AliExpress specials don't do those things well (or at all).
Yes I bought a bunch of 8x25" Intel bays and outfitting 4xNVMe and 4xSATA.
Two SLG3-2E4 adapters with 4x SFF-8643 work well with most any computer with PCIe 3.x
Haswell and upward...
I have defaulted to standard mode of gmirror anything I boot if possible. So two drives on one card make logical sense to me.
Build out rest from there. I don't feel comfortable using ZFS bootenvs though I enjoy ZFS features..
You could probably boot these cards on PCIe 2.x motherboards at reduced bus speed...
Build out rest from there. I don't feel comfortable using ZFS bootenvs though I enjoy ZFS features..
You could probably boot these cards on PCIe 2.x motherboards at reduced bus speed...
Just concerning the Oracle card:
Sadly "mattventura" seems to be right. I so far only had connected the card itself, but didn't have time to check with connected devices. Tried that today, with an adapter card and two NVMes on a CoffeeLake Desktop system.
No devices visible at all, while the switch itself is listed correctly in "lspci".
The question now remains, if there is an easy way to make it work. I would guess, that it isn't much, that is missing. However, without schematics, it might be some real trial and error. Of course could involve considerable amounts of time.
So, I retract my opinion, that this card might be a good idea to get! Thanks matt!
Sadly "mattventura" seems to be right. I so far only had connected the card itself, but didn't have time to check with connected devices. Tried that today, with an adapter card and two NVMes on a CoffeeLake Desktop system.
No devices visible at all, while the switch itself is listed correctly in "lspci".
The question now remains, if there is an easy way to make it work. I would guess, that it isn't much, that is missing. However, without schematics, it might be some real trial and error. Of course could involve considerable amounts of time.
So, I retract my opinion, that this card might be a good idea to get! Thanks matt!