Quanta LB6M (10GbE) -- Discussion

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fohdeesha

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Any news here ?
yeah, it'll be dead easy once I get ahold of the dell bootloader by itself. It's buried in the dell STK as a separate LZMA compressed partition, and inside that partition is an update routine, and somewhere in that routine is the smaller actual bootloader section that it copies to flash during the routine. Been slowly working my way backwards with a disassembler until I get to the instruction that copies to flash, then I'll have the location within the update file it's using

If anyone wants to save me significant time, patch this to support CRC16 instead of CRC32 and it'll take me 20 seconds to find it :p GitHub - claunia/findcrcs: Find and extract pieces of data by CRC, size and MD5

(you'll also have to add #include <errno.h> to the beginning of findcrcs.cc to get it to build succesfully)
 

alexhaj

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Jan 12, 2018
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alexhaj

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So the pinout partially works. I can see the serial output but I cannot transmit anything back over the connection. Am I missing something?

update...I am just going to order the cable.
 
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fohdeesha

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I desperately need someone with a stock LB6M, not flashed, to go into the bootloader, run "printenv" and pastebin me the output. For a revert procedure, no ethernet connectivity on the thing until I have that output :( EDIT: got it, thanks!
 
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Foray

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May 22, 2016
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I desperately need someone with a stock LB6M, not flashed, to go into the bootloader, run "printenv" and pastebin me the output. For a revert procedure, no ethernet connectivity on the thing until I have that output :(
Dissect that bootloader I sent you, the default environment variables should be in it plaintext.
 

fohdeesha

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It has the default/fallback uboot env variables, but it seems there's different ones somewhere else on flash (have the address written down somewhere, not at home atm) that it pulls from. It seems also it pulls from eeprom for the ethaddr variable, maybe others as well. The fallback variables in the 512k bootloader file don't actually even work to allow networking, ethact and a couple others need changed, so I'm thinking there's more that I'm missing.

edit: seems they get stored here:
0x00000000-0x01f80000 : "jffs2"
0x01f80000-0x02000000 : "u-boot"
0x01fc0000-0x01fe0000 : "u-boot-env"
 
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Ryan Anstey

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Jan 17, 2018
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Although the instructions are easy, and everything is quite easy to see, if you still aren't sure about this, please don't mod/replace the psu fans yet and WAIT till i post pics of what i EXACTLY did. I will cry if you blow up your psu on this sweet 10gigabit switch.
Any chance those pics have been posted yet? I have fans in need of replacing :)
 

TheBloke

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Feb 23, 2017
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Any chance those pics have been posted yet? I have fans in need of replacing :)
EDIT: I realised too late you were talking about PSU fan replacement, and already read posts I was going to add :)

I'll leave the following as a summary for newcomers regarding normal fan replacement and some links to fan mods.

To do a like-for-like replacement of a fan is super easy. The entire fan tray simply unscrews in the same way as a PSU does - two thumb-screws at the back, then pull it out:



Each fan is then held in with two diagonally-opposite screws into the back plate of the fan tray.

I've not yet replaced one myself, but one of mine is intermittently failing so I might do soon. The 4-pin connector is a different wiring to standard, so this needs to be checked for (see below.)

Here's a close-up of a fan:



By AVC, model number DB04028B12U. I can see a few on eBay - there's some cheap ones from China, but they're only 3-pin. But apparently the same fan is used in an HP ProLiant model, and there's some of those - albeit rather expensive.

Best of all is to put in one or more quieter fans, as others have done. Again, be aware that the 4-pin wiring is different to a normal fan, potentially requiring swapping pins on the connectors.

Here's a post from a guy who's done a single-12cm-on-the-top mod.

And here's Sleyk's mega-post on doing a fan mod, including lots of photos and discussion of the different 4-pin wiring.
 
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Ryan Anstey

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EDIT: I realised too late you were talking about PSU fan replacement, and already read posts I was going to add :)
Thanks! I appreciate the effort to help. Any idea how dangerous the PSU fan replacement job is? Opening a PSU in general sounds scary... hoping this one is just unplug fans, do a tiny mod to the new ones and plug them in. (My new fans just arrived from Amazon.)
 

TheBloke

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Thanks! I appreciate the effort to help. Any idea how dangerous the PSU fan replacement job is? Opening a PSU in general sounds scary... hoping this one is just unplug fans, do a tiny mod to the new ones and plug them in. (My new fans just arrived from Amazon.)
I haven't opened these PSUs before, but I have opened other PSUs before and they're not really that different to opening anything else. A little cramped maybe.

If the fan screws in and has a standard 3 or 4-pin fan connector, I can't see why it would be all that hard. But as I say, I've not opened it so I don't speak from specific experience.

If it were me I'd certainly open it up and if it seemed straightforward, proceed. Only if it seemed like I was going to have to do a custom job - drilling holes etc - would I pause.

Of course, if you have dual PSUs as I have, that gives you some insurance. As long as you can be sure you're not doing anything dangerous, it's probably worth a go.

I think I've seen @Sleyk around on the forum in the last days though, so he may well pop up soon to give more specific instructions. Always nice to do it after someone else has already been the guinea pig :)
 

TheBloke

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OK @Ryan Anstey I've just been your guinea pig. It all seems very easy mechanically, at least as long as your fans are identical size, are 3-pin, and are the SAME 3-pin. But the latter bit may not be true - more details at the end.
  1. Undo the six screws around the sides of the top panel (at the top of the left/right edges)
  2. Undo all the screws you see on the top panel
  3. Undo another 2 screws at the back end of the PSU, where the connector is, underneath - you can see the top panel wraps around to be held here at the bottom as well.
  4. Remove the top cover and the paper cover underneath:
  5. Now unscrew one fan from the PSU: each is held in a metal bracket, and the bracket is secured to the case via two screws: one to the outside of the case (look at the side of the case nearest to that fan), and another down into the base of the case, adjacent to the motherboard.
  6. You can now unplug the 3-pin connector, unscrew the fan from its metal bracket, and put in the replacement.
  7. Reverse the above steps to re-attach.
Unfortunately it is not possible to test this outside of the switch, with the case off. I just tried, by applying power when the PSU was out of the switch. The PSU light comes on, but nothing powers up because nothing is found on the connector.

So you'll have to put it all back together and test it inside the switch.

Before changing any fan you need to check if your new fan has its 3-pin fan connector wired differently. The fan in my PSU is AFB0412VHB, The datasheet is here. This indicates that red = +12V, black = ground, and blue = speed measurement. That's fine. But it appears the ordering on the 3-pin connector is perhaps not standard, or at least this can differ. And the ordering shown on page 6 of that spec doesn't match the ordering I see on the real fan in the PSU.

Checking the connector on this Delta fan in my PSU, I see that the order of the wires when looking at the side of the connector that has the notches is: Red, Black, Blue. I then took a random 3-pin fan out of my collection, and looking at this connector the same way, it was Yellow, Red, Black. Yellow will be the same purpose as Blue, the colour change is fine. But the connector appears to be wired completely differently:



On the left is the original PSU fan connector, on the right the one from a random 3-pin fan from my Box Of Fans. I double checked the data sheet for the other fan, a Sunon, and confirmed that as expected red = +12 and black = ground, so everything is definitely in a different order.

And I checked another couple of fans in my box, and they match the Sunon. So it's clearly the PSU fan that's different.

Therefore you should definitely expect yours to be wired differently, unless you bought the exact same model - and even then, check, as the datasheet for the Delta fan in my PSU seemed to indicate a different wiring than what's actually in the connector. So they may be standard Delta AFB0412VHB fans but with custom connectors.

It may be possible to simply pull the wires and pins out of the connector and push them back in another order - though sometimes they don't stay tight after that.

If not, you can buy 3-pin connectors and their pins, cut the connector off your new fan and then solder the new pins on and push them into the new connector in the right order. I've never done it with these fan connectors, but have with many other kinds of 2 and 3-pin connectors. Are you comfortable using a soldering iron?
 
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mrsonicblue

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Jan 20, 2018
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What I ended up doing with the PSU noise is to keep the original fans, but add an inline resistor to slow them down somewhat. If you know what you're doing, it would cost less than a dollar for a resistor. If you're lazy, like me, you can buy a pre-made cable that you insert between the fan and the PSU. I used the Noctua NA-SRC10. You can get them in packs of three for about $8 total. They reduce the noise CONSIDERABLY.

That said, I have no idea if this will eventually damage the PSU. As someone above pointed out, there are two PSUs. I'm willing going to run with it and if it ever burns up, I can try something else with the second PSU. I'm not pushing huge amounts of data, so hopefully the heat is manageable.
 
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TheBloke

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What I ended up doing with the PSU noise is to keep the original fans, but add an inline resistor to slow them down somewhat. If you know what you're doing, it would cost less than a dollar for a resistor. If you're lazy, like me, you can buy a pre-made cable that you insert between the fan and the PSU. I used the Noctua NA-SRC10. You can get them in packs of three for about $8 total. They reduce the noise CONSIDERABLY.

That said, I have no idea if this will eventually damage the PSU. As someone above pointed out, there are two PSUs. I'm willing going to run with it and if it ever burns up, I can try something else with the second PSU. I'm not pushing huge amounts of data, so hopefully the heat is manageable.
Yeah that's a good idea. I've used those cables in desktops and servers before. A worry is that there's no temperature monitoring of the PSU - I can't see any option in the switch OS, either the original Quanta or the newly-flashable Brocade - that monitors the PSU. So there'd be no way to see if temperature is building up. However, one would assume it has over-temperature protection, so as long as one is OK with it potentially shutting down the PSU and switch without warning, it's likely a risk worth taking. As you say, given many of us have two PSUs and are using them at home, it's probably no big deal. The cooling is designed so as to be able to always cool the PSU when at full, sustained power consumption, in a hot DC. As you say, at home we're unlikely to reach that - at least as long as the switch is not stuck in an un-ventilated cupboard or something :)

However, personally I'm thinking of doing a double 12cm fan mod: remove the 3x main switch fans and replace with a single 12cm fan mounted on the top panel above the processor area, and then cut a hole in the lid of one PSU and mount a second 12cm fan in the panel above it, so it now vents straight up. I never plan to run with dual active PSUs, so I only need to provide ventilation for one fan bay, and only mutilate one PSU.

A couple of 12cm fans at up to 2000 RPM each will be more or less silent, certainly compared to all my other server gear.
 
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TheBloke

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What I ended up doing with the PSU noise is to keep the original fans, but add an inline resistor to slow them down somewhat. If you know what you're doing, it would cost less than a dollar for a resistor. If you're lazy, like me, you can buy a pre-made cable that you insert between the fan and the PSU. I used the Noctua NA-SRC10. You can get them in packs of three for about $8 total. They reduce the noise CONSIDERABLY.
Hum.. I just had a thought: if you used a standard off-the-shelf fan speed cable, did you come across problems with the different wiring of the fan connector? The fan speed cable will put a resistor on a certain pin, and if the wiring is different, it could end up in a place where it won't work.

Though actually, it appears on my differently-wired fan that Ground is where +12 normally is. So if your cable has the resistor on the +12 line, then with the different connector it would end up on the Ground line. Which would still work. However, if it had the resistor on ground, it would end up on the blue/fan speed wire, which wouldn't slow the fan down and would presumably break the fan speed monitoring.

So either your fan isn't wired differently, as mine appears to be, or else I suppose the resistor must be on +12 and that got swapped to Ground which still works? My electronics knowledge is shamefully limited, but I do know that in a simple circuit, a resistor works the same way whether it's on the ground wire or +12v. Either way it will limit the current of the overall circuit.

So yeah I suppose it's most likely that.
 
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mrsonicblue

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Hum.. I just had a thought: if you used a standard off-the-shelf fan speed cable, did you come across problems with the different wiring of the fan connector? The fan speed cable will put a resistor on a certain pin, and if the wiring is different, it could end up in a place where it won't work.
I added the resistor a few weeks ago and didn’t think to check the wiring. The fans are definitely still spinning, but slower. I’m attaching the only picture I took of the fan, in case it helps.
 

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