12 KiB
title, subtitle, date, toc, tags, draft, author, author_email, listing_image
| title | subtitle | date | toc | tags | draft | author | author_email | listing_image | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| How to get 120 disks into a single chassis | Building a NAS from an old chassis | 2024-03-04T00:00:00Z | false |
|
true | Andrew K | leighhack@shamrock.org.uk | images/IMG_2905.jpg |
As it turns out this is a little more complicated than I expected, even when you start with a larger chassis. My drive to do this, a combination of power requirements, storage space and actually can it be done!
The Chassis
I have several of these from an older project
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These are 4RU in height, wide and deep enough to sit on a 19" rack shelf and cabinet and are quite old now, >10 years. They were bought for a project which did not get much passed the development stage.
They came from here BackBlaze and I believe you can still order the chassis although no longer sold as a working solution, such that you have to outfit them yourself.
I have put them on ebay on more than one occasion but never got the price I thought they were worth, so just kept them. In all seriousness I probably should have sold them, however I have 3 that were fitted out and 2 empty chassis. There are some covers missing from one, but I digress a litle.
If you open the large cover you find it has a location for 3 1/2 45 disks, see the link above, it goes into plenty of detail.
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The drives sit in the grid and the vibration of the disks spinning is dampened by some rubber bands, you can see a couple in the picture.
The drives are hot swappable and plug directly into a PCB, of which there are 9, each controlling 5 drives. The controller cards are actually just SATA port expanders, and in comparison to many port expanders work relatively well.
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Unfortunately these can not be re-used in this project as we need the locations they are in to put new disks, and more of them. One thing these do provide are the screw locations for the underneath. To be discussed more later.
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Starting from empty
I stripped out all the port expanders and all wiring to go with them and you can see it here, so just an empty chassis
I left the nylon posts in place as they are threaded and allow the nylon screws, they were holding in the port exanpders, to be used.
If you do have one of these chassis and need the nylon posts they are
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The screws are
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Both of these are still available to buy.
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What components do I have
I am going to reuse the motherboard and as many components, fans, cables etc as possible. The motherboard is a supermicro X9SAE-V.
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It has 6 PCI slots , on board HDMI and dual GigE, it is old, but will at least get things going.
After boot it shows the CPU is an old i5
This is not going to set the world on fire with CPU capabilities but should be enough to make it work without spending too much money. This is after all a project rather than anything to be used in production (yet!)
So at this point we have a working motherboard, a case, locations for a PSU and drive bay location.
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We also have 3 of these
Nothing amazing, but simple 4 port SATA controllers.
Comparing drive sizes
Next I started to look at the size of the drives. I wanted to move away from spinny disks, power, noise, heat the primary factors but also fully loaded is very heavy!
So to keep things compact SSD form factor 2 1/2 is the way to go.
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Let's compare the sizes
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I created a 3d printed flat platform that the drives could stand on, just to test out how many seemed reasonable
Cabling
At this point I realized the cabling would not fit under the platform, so any new location for the drives would either need to be custom with driver chip (like the previous items) or just connectors with drivers elsewhere, but also with the SSDs being smaller (hence shorter) there is now more room to move things upwards, as it turns out about 35mms of room.
I then 3d printed a mask, that would allow me to use the nylong screws into the positions in the chassis but also allow me to add additional holes for anything I wanted to attach, so removing the need to match holes but allow me to extend upwards
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Drive capacity
Now to get more drives into the chassis, I initially went for 10 drives , instead of 5 per location. This then required the use of port expanders, so I bought a few of these.
As it turns they are little rubbish. Not because they do not work, or that they are insanely slow but if you buy them from anywhere the heatsink is stuck in place with some kind of double sided heat resistance tape, which transfers little heat to the heatsink. This causes them to restart regularly when in use, rendering them next to useless.
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If you remove the heatsink, apply heat and it will come off
Then if you put it back with heat transfer epoxy, it will stop restarting, but remains incredibly slow!
But I did push on and get it going
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I got some custom PCBs made from PCBWay
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Nothing clever, just locators for the connectors , nothing active. Then then came up with a design to have the port expanders underneath, so two per location, giving 10 drives.
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and then with the PCB in place As you can see, it kind of fits ?
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So in my wisdom I thought I could fit more connectors on the PCB, so I went for 14 drives per PCB
Two rows of 7, I would have two port expanders underneath and using some method not determined find a location for a 3rd one. If I have 9 slots, 14 x 9 = 126 , so I get to my goal with a few to spare!
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So a completed PCB
It is a very simple design, two locations to power the drives and then pass through connectors for SATA
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Then I wired it up with the SATA cables I had
It looks pretty, and did work, 20 drives and a boot drive, so 21 drives.
At this point, which was quite a bit of work, I realized with much distress, it was slower than a snail, at one point I was getting an underwhelming 10Mb/s !!!
The current status
- Three PCBway prototypes ( one not mentioned here was a disaster )
- Multiple port expanders ( 5 in total, after destroying one )
- Not solving the space problem for an additional 3rd port expander use
- Lots of SATA cabling, testing
- OS install, re-install, RAID testing, multiple controller etc etc
- Very slow performance
A regroup and what to do next
The final design of the PCB , 2 x 7 slots I was keeping, even if I did not use all the locations, it works, there are air flow cut outs. It also now matches the mask to connect to the chassis.
I now need to find a solution to control a large number of disks, without breaking the bank and also consider how would cabling work for all the drives
If you look at this motherboard it is 2 x 1x and 1 x 2x and 3 x 4x PCIE interfacers so options are limited on the number and type of interface cards.
There are multiple SATA cards that provide good 8x SATA interfaces such as this StarTech
it's a fast card, does the job well, so with 3 of these in I get 24 ports. Alas not getting me close to the 120 I wanted, so no real use.
Time to go SAS
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SAS cards are incredibly cheap and relatively quick and compatible with SATA drives, not to be confused with SAS drives ARE NOT compatible with SATA controllers. This one is goes for about $30 and has 2 ports on board.
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To make the best use out of it you also need to expand the number of ports available, which is where this card comes in.
It is an Intel RES2SV240 RAID card. It is not really a RAID card in this case, but provides 24 ports, of which 4 are inbound and 20 outbound. This card is relatvely good as you can then use SFF8087 cables to SATA ports, keeping the cabling manageable, rather than individual SATA cables
So let's do the maths
- SAS card - 2 physical ports
- Intel RES240 - 20 outbound ports, so based on the LSI card , 2 of these connected per LSI card = 40 ports
So three (3) LSI cards and 6 RES240 cards = 120 ports. We are there.
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Even better the RES240 cards do not actually need to plug into the motherboard, they just need power and are fitted with an external power socket!!!
- This is an amazing win.
- I started the build out as follows
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Add some drive location testing
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It is brilliant what could go wrong!
As it turns out ... there is always something!
When I added an additional 14, the SAS controller only showed 24, but 14 + 14 = 28
It turns out SAS controller cards do not have an unlimited number ports, they can only service 24 drives per card! Some mention 16 , some 32, all the ones I bought that touted different numbers, the upper limit was always 24.
The best we can do with 3 controllers is then 72 drives ( 1 RES240 card + other physical port to 4 drives ).
Close but not yet 120 drives - ARG!!!!!