[tech] More space on Molmol

Frames oxinabox at ucc.asn.au
Fri Aug 5 17:22:58 AWST 2016


Ok, here is the deal with Molmol. We're running out space.  The 
situation is just below and the potential solutions are under that.

  * It has its book disk on an internal USB.
  * It has its system disk on a 2.5inch SSD internally.
      o Using 1 of its 4, motherboard SATA 3 (Black) ports
  * It has 2 2.5 inch SDDs in raid for disk cache in the first 5.2inch bay,
      o they are connected to its Motherboard SAS (White) ports (running
        SATA3). There ports are not multiplexed -- that are endpoint
        SAS, ie SATA ports
  * It has piles of SATA 2 ports on the motherboard. Like 8 or so. These
    are Blue.
  * It has nothing in the bottom 5.2 inch bay, and it's fully accessible.
      o *We could stick some hard drives of any description here *(may
        be hard to get 2 x 3.5inches)
      o And use any of the free connectors (prob SATA3 -- of which we
        have 3 )
  * It s 8 taken 2.5 inch bays (hotswappable), which match to 2 4x SAS
    multipliers, which we have connected to the two ports on its SAS
    card and we run SATA 3 through that.
  * It has 8 free 2.5 inch bays (hotswappable), which match to 2 4x SAS
    multipliers
      o due to the physical nature of the SAS multiplexer (all 4,
        multiplexer are on once card), we can probably not directly
        connect those to SATA cable*** (more or less, see below)

That more or less summarizes what we're working with. Here's the 
potential angles of approach.
/NOTE: No matter what we do, we need to add drives in pairs, for RAID 
1+0, and we really would like at very least 2TB more space. Which 
requires at least 4TB of drives../

  * The straightforward approach is to buy a new SAS card, allowing us
    to mount 8 2.5" more hard-drives in the existing bays.

      o This is what [BG3] suggested
          + [GOZ] likes this since it is good to have them before our
            exact model  goes out of production
      o Issue with this is that there is not much range on 2.5inch
        disks, they are relatively expensive and small.
          + I guess the bet that was made when choosing the case, that
            2.5 inch cards would be come the norm, did not pay off.
          + The only 2TB 2.5 inch disks are Toshiba laptop hard drives
          + Otherwise you are stuck with the 1TB WD-Reds, which is what
            is has in its taken bays.
      o According to [BG3] a SAS card + 8WD reds (1TB), was $1.3 grand.
          + Buying a SAS card alone is $200-$400
      o This is much more expensive than the numbers from several years
        ago
        http://wiki.ucc.asn.au/MoneyMoneyMoney/NewStorage#Level_2:_Optional_extra.2C_add_a_SAS_card
        of $929

  * *** The drives plug straight into the SAS multiplexer, *but there
    are holes in the SAS multiplexer plate* which you can just squeeze
    SATA and power through
      o [GOZ] believes, that mounted in the hotswap bays they will be
        too close to the end to fit the SATA plug in (after going
        through the holes in the SAS multiplexer plate).
          + Having examined it now, there is room to push the cards
            forward in the hotswap bays, and drill new mounting holes,
            and then we would have just enough space to to put in the SATA
          + Or we can just not push the hotswap bays all the way in.
      o Eitherway, *connecting these to SATA *would let us save on
        buying another SAS card

  * The other option would be to get the capacity to have 3.5 inch disks
      o One way would be to *move to a new case that has 3.5 inch bays
        *(Possibly one of the spares we have laying around)
          + This would mean replacing all our disks with 3.5 inch disk,
            or just leaving the 2.5in rattling around in the over large
            slots
              # This isn't such a big deal since 3.5 inch disks are cheap
      o The other, really Hacky way (that [*OX] likes) is to *Mount
        another case on top of this case*
          + This would involve cutting a hole in the top of the existing
            case, and the bottom of the one we put in top
              # Could basically remove the bottom of the top one and the
                top of the bottom and bolt/weld them together. For a
                huge 5RU-7RU case.
          + This would make deracking molmol pretty shit
          + It would however let us have hotswap both 3.5 and 2.5 disks
      o Either way This is compatible with either using the spare SATA
        ports on the MB, or with buying another SAS card.
      o Potentially, but not necessarily may require buying a SAS
        multiplexer

So wheel members/committee members, how would you approach this 
situation? Bear in mind the club is stingy (committee doesn't really 
want to pay $1300 for 4TB of extra space)

[*OX] / [CHS]
Wheel Members

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