"Server Cabinet" rebuild questions and advice

Discussion in 'General Chat' started by Iain Stott, Feb 25, 2017.

  1. Iain Stott

    Iain Stott New Member

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    Ok, so I'm looking at moving most of my servers/home lab equipment to a new rackmount style custom built cabinet because I'm looking to add some new hardware into the mix. I already have one ATX pc in there, and I am looking at adding another for firewall plus maybe a 3rd if I get a decent price on it.

    I have a 1.2Kw Dell PSU doing nothing and was wondering if it would be feasible to run the 3 boards from the one PSU?? I've done some reading up on the subject and have seen its achievable but a bit confused as to what issues I may have. The PCs in question are 1x i7 920 Dell/Alienware Mobo and nVidia 210 GPU (no dedicated power from PSU) this is my main rig and proxmox host, Q6600 Gigabyte GA-EP45 mobo undecided GPU but again will be low power fanless model this will be firewall, and then a 2nd gen i5 mATX with onboard GPU for testing/2nd proxmox host. Between them they will have 10x 3.5" HDD, 2x SSD, a DVD burner, 2x USB TV tuner adapters, 2x Quad Port NICs. Cooler Masters PSU calculator has given me 900w so I think I have room, but just need some other peoples advice on the subject.

    I've modded a couple of PSUs to be on all the time by shorting the green wire to ground and adding a load to 5v in the shape of a 10w resistor, which is what I am thinking of doing to this scenario.
    What I am unsure of is the behaviour of each motherboard in this situation. I still want to be able to power down each motherboard individually to work on them so will this still work??

    Cheers
    Iain
     
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  2. pricklypunter

    pricklypunter Well-Known Member

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    Assuming that you intend to parallel the Mainboard connections and disk connections etc, you should not need the 10W resistor. You might want to consider adding some logic to your power switches and power good signals etc to achieve the ability to individually switch the boards on/ off, like wired OR, for example, to control power good back to the supply. You will likely also need to control the power rails themselves with some relays etc, to prevent boards/ disks powering up when not intended, but that should be simple enough to achieve also. The whole thing could be controlled by a small micro-controller and some discreet components, and keeping with the tradition of feature creep, you could then add an LCD display showing you status of each board, power supply statistics etc etc :)

    Not too many things are impossible given time, will and budget, the only limit is your imagination. You would most likely be less money just tossing 3 low power off the shelf supplies in there, but where's the fun in that :D:p
     
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  3. Iain Stott

    Iain Stott New Member

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    Cheers pricklypunter, you've just written everything I was thinking I'll need to do. I was only looking at adding the 10w resistor as I have them knocking around and I'm planning on running some 12v components off this power supply so would want them on if all motherboards were off so the resistor is sort of a backup to do that. One of the 12v is an Arduino which I was thinking of using for relays to control the power switch to the board to turn them on and off but was unsure whether this was the right solution with the power supply being on all the time. This would also give me the ability to set delays between each board powering up so they're not all booting at once when first switched on.

    I've been thinking about Power Good wire (not looked too much into it yet), can this be used to control the power state of the motherboards?? Like if I use a relay to control it, when it is set to the motherboard it will switch on, or will it work using the power switch jumpers on the mobo.

    Most of the components I already have, so I like utilising what I have before buying new, plus space is sort of at a premium, so in my mind adapting one PSU would give me more space to play within the enclosure and less wiring to adapt/contend with and keep neat. I plan on using single 14awg wire from the PSU to as close to the motherboard as possible, then branch off that for all the wires on the 8pin and 24pin, obviously separate wires for each 3.3, 5, 12v and gnd, but only one for each.

    So looking at my PSU it has 8x 12v rails each at 11.5A, If I have a 24pin and 8pin connector on each rail for each motherboard, HDD's on another rail (or two), is 11.5A enough juice for a motherboard and CPU?? GPUs aren't really used as all machines run headless and GPUs only installed to enable the boards to boot.

    Thanks Again
    Iain
     
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  4. Jeggs101

    Jeggs101 Well-Known Member

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    I've tried this type of setup. Just go with multiple psus. It had too many quirks.
     
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  5. Iain Stott

    Iain Stott New Member

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    Cheers bud, what sort of quirks did you encounter?? Only because I think I'll probably doing research into this before making my decision once the cabinet is fully designed and most parts bought. Will give me enough time to work out some quirks in testing but wouldn't mind having an idea before hand.

    Thanks
    Iain
     
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  6. pricklypunter

    pricklypunter Well-Known Member

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    I would only use the relays to handle the high current power rails, all the lower current logic stuff, like soft power on etc, I would want to use fast switching MOSFET's for. With careful design, you could also use FET's to handle the power rails, but it's probably easier to just use a couple of relays and a software delay to act as a dummy power good signal :)
     
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  7. Iain Stott

    Iain Stott New Member

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    Cheers bud, you gave me food for thought with that reply. I think I'm going to use High Current FET's to control everything as I think they will fit my requirements better than SSR or the like. I am also looking into using an optoisolator to "sense" the state of PW_ON from the motherboard to control the power supply to the board, in my mind this should now act like a normal PC?? I should be able to shutdown from OS normally or with a button connected to the motherboard??

    At the moment work has started on building the cabinet and I'm probably about 20% of the way through. The structural frame is built along with some partitioning and I'm just 1st fitting some of the hardware. Going to start on wiring it up once the fuse box and wire arrives.
     
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  8. Iain Stott

    Iain Stott New Member

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    Right so I've been buying again, throwing my original plans semi-up-in-the-air and now I'm confused.
    So I won a old HP DL380 G6 on eBay. Dual X5560 Xeons and 72gb of RAM. So now I have a server that can do everything I want from all the ATX boards combined which probably won't get used in this project now.

    My original plan was to have all my "Storage" drives attached to my i7 main proxmox host in JBOD type of afair. Then I got to thinking about redundancy, data loss and speed and started looking at raid (never used it before) and now I have this server am now looking at zfs.

    My plan was to use a 3.5” SAS HDD backplane and a PCI-E raid controller to connect it all to the i7, but can I just now connect the backplane to the external connector on the back of the server??

    Then after that, for a home user is there any need for zfs considering I'm not doing anything mission critical or that is going to have any dire consequences if it gets destroyed. Can I just use ext3 on raid 1 and be happy??

    The drives in question are
    2x 4tb
    2x 3tb
    2x 2tb

    Sent from my m8 using Tapatalk
     
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  9. pricklypunter

    pricklypunter Well-Known Member

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    The HP SAS controller card that was normally fitted standard on those was the P410, which is not really the best choice if you want to use any kind of software based raid, it's only capable of 3Gbps and being HP's own, may also limit the drive size/ type you can use along with it. Also, as I remember the P410 is an internal card, and you mentioned having a "rear socket", so perhaps it's fitted with something else entirely, so I would check that out first and see exactly what you have in there. Depending on what you find, swapping that card out for one of the LSI based boards that are better suited to the task would be more beneficial, like the ubiquitous IBM Serveraid M1015 or the Dell H200/310 etc. As for raid level, that really is a choice you need to make for yourself, based on your requirements for capacity/ redundancy/ performance.

    Raid "flavour" is a debate that could last a lifetime, the same goes for filesystems. Each has it's upsides and down, they all have their foibles. Just how important your data is to you or how easily managed it is may well influence your decision here, for example, ZFS checksuming affords a level of protection against bit rot, basic mdRaid with LVM is easily grown by adding disks rather than vdev's etc. Then there's the hardware vs software based raid question. IMO, software based raid is the only sensible route to take nowadays, modern processors just shrug off the overhead associated with parity based raid, but in certain circumstances a hardware based setup might be better :)
     
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