Rack-mounted Mac mini power problem solved by remote servos

AppleInsider

A hardware hacker has solved a problem of powering on 16 Mac minis in a rack, by using a Raspberry Pi to physically press each power switch.

A Raspberry Pi-controlled Mac mini server rack [X/@merocle]

The Mac mini has been used in the past as a compact server, with applications ranging from typical server-related functions to virtualized macOS desktops such as MacStadium's Orka Workspace.

However, one of the problems of running a Mac mini in a server racks that its physical button occasionally needs to be pressed, such as to turn them on. Server racks pack as much hardware into as little space as possible and are intended to be left alone and remotely managed.

Another stand of 16 Mac mini's mounted.
The third
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-- Ivan Kuleshov (@Merocle)

August 17, 2023

That situation can make it difficult to put many Mac minis into a rack space while still allowing the buttons to be accessible.

Shared on Twitter, hardware hacker Ivan Kuleshov has come up with a system for mounting multiple racks of Mac minis in a standard server rack. In his implementation, 16 Mac minis are installed at a time into a larger case, all with the ports angled up for accessibility.

To solve the problem of manually turning on all 16 Mac minis remotely, Kuleshov uses a Raspberry Pi, best known as an electronics-friendly and low-cost computer on a compact board.

To that board, he attaches a number of servo HATs (Hardware Attached on Top), which in turn controls a series of eight servos. Eight servos are used since each can press the power button on two Mac minis.

On top of the Servo HATs, the Pi is running PiKVM, an IP-KVM system, and has enough space left over for a small informational display. It's all packed into a custom case, and mounted inside the cabinet alongside the Mac minis.

Kuleshov has a lot of experience with the Mac mini, having previously created a hack for the Mac mini to make it run over Power over Ethernet. This is also not Kuleshov's first server rack of Mac minis, as this project is his third-such arrangement.

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mayfly

Isn't always being powered on the purpose of servers?

mikethemartian

I think they sell remotely controlled power outlet strips for this exact purpose. At least for PCs.

bijryx

Can't you configure a Mac to automatically power on after a power failure?
This way you wouldn't need to press button since it would start automatically when it has power.

tomahawk

mikethemartian said:

I think they sell remotely controlled power outlet strips for this exact purpose. At least for PCs.

And I haven't used it in awhile but I think they can still be configured to automatically turn on after a power outage.  I would think a simple remotely managed PDU would accomplish almost everything I can think of that would be needed.

Heck, if they're still playing with PoE, they could kill the PoE at the switch to that specific Mini and then turn it back on again. It should power up if configured properly.

Also, if that rack is using the typical front to back cooling, isn't mini 16 getting way worse air than mini 1?  They may not generate that much heat but still. Maybe it's pulling cool air from the bottom of the enclosure?

maltz

At some point you have to ask if a row of Mac Minis are the right tools for the job...  probably a point well before this.  lol

caprica

That is very ingenious and is similar to how AWS powers their minis > https://www.servethehome.com/how-aws-added-apple-mac-mini-nodes-to-ec2/ - AWS has some relay mechanism to power up the Minis as well.

caprica

This makes me wonder if Studios and Pros could be set up in rack as well - I'm not considering applicability, just technicality of it.

22july2013

If the Mac Minis also had a servo over the power buttons of the Raspberry berry Pis, would that mean Judgment Day is near?

danox

There are people out there using multiple Mac’s on racks, i’m sure things could be easier if Apple started to take revenue and profit off the table with her home designs in that area of computing, particularly for small to medium size businesses that want to connect all those Apple devices together seamless manner. Probably on Apples to do list in the future. Don’t let those three guys who used to work at Apple, who quit and started Nuvia (now owned by Qualcomm) get there first.

https://www.youtube.com/watch?v=xq_oQnqk85U&pp=ygUUbWFjIHN0YWRpdW0gc3RhZGl1bSA%3D

https://www.youtube.com/watch?v=iUyTeGKzQlA&pp=ygUUbWFjIHN0YWRpdW0gc3RhZGl1bSA%3D

https://www.youtube.com/watch?v=0b46E4mp_V8&pp=ygUUbWFjIHN0YWRpdW0gc3RhZGl1bSA%3D 

https://www.youtube.com/watch?v=OH8_2u7-JVI

cpsro

As Bijryx notes, just configure the Mac in Settings to "Start up after power failure." I do this with all my servers (Macs included) and plug them into inexpensive power outlets that can be powered on/off/toggled remotely. There are many controllable power outlets to choose from.

Merocle

Hey, everybody!

thank you so much for your comments.

The main question as I see it is "why?"

I'll try to answer that:

1. Why is Mac Mini in the server room?

It is the best and actually, the only reasonable (in terms of price and number of cores and RAM) option for developers to build and test software under the Apple Silicon platform. Especially if there are a lot of developers in the company.

2. Why servo drives?

It is the only option to have full control. It's not a question of being able to switch them on or off. The question is to be able to switch to the recovery mode and completely reconfigure them. To do this, you need to hold the power button for about 7 seconds.

I may not have covered this issue in enough detail in this comment. But I will try to write about it in detail on my website when I prepare the article.
Thanks again to everyone!

Merocle

caprica said:

That is very ingenious and is similar to how AWS powers their minis > https://www.servethehome.com/how-aws-added-apple-mac-mini-nodes-to-ec2/ - AWS has some relay mechanism to power up the Minis as well.

Yes, I researched their solution (from what I could find online). They use a solenoid to push a button on the Mac mini, and they also use external storage so as not to wear out the life of the inbuilt SSD. I suspect that both the Mac mini and AWS Nitro controller have access to this storage so that they can reload the OS bypassing the Mac mini.

Well, I would do that if I didn't have budget constraints and I needed to implement a similar solution for hundreds of Mac minis.

FileMakerFeller

Merocle said:

Hey, everybody!

thank you so much for your comments.

The main question as I see it is "why?"

I'll try to answer that:

1. Why is Mac Mini in the server room?

It is the best and actually, the only reasonable (in terms of price and number of cores and RAM) option for developers to build and test software under the Apple Silicon platform. Especially if there are a lot of developers in the company.

2. Why servo drives?

It is the only option to have full control. It's not a question of being able to switch them on or off. The question is to be able to switch to the recovery mode and completely reconfigure them. To do this, you need to hold the power button for about 7 seconds.

I may not have covered this issue in enough detail in this comment. But I will try to write about it in detail on my website when I prepare the article.
Thanks again to everyone!

I love the config you've chosen, but it looks to be 6U high. From my rough calculations you could have a 2x3 flat grid in a 1U space; if you place the minis so their rear faces the sides of the rack you get a channel where you can run cables. Is it just too tricky to get a servo arrangement into that space as well?

darkvader

maltz said:

At some point you have to ask if a row of Mac Minis are the right tools for the job...  probably a point well before this.  lol

Oh, it isn't.  But since Apple killed the Xserve, it's the only tool we've got.  VERY stupid move on Apple's part.

JamesBrickley

There is more to it than just having a servo press or press-hold the power button.  You need to have some sort of KVM connected to HDMI or USB-C Display and KB/mouse and route the video to remote control of some sort.  The SSD's are factory encrypted and turning on FileVault only generates a public/private key, stuffs the private key into the Secure Enclave and uses the public key to generate the FileVault Recovery Key which gives you a way to reset the password if forgotten.  If a M1 / M2 Mac Mini is rebooted in the data center, it comes up to a pre-boot authentication screen and it's not online with the network.  When you enter your ID/PW it then boots macOS and single-signs onto the desktop. If the passwords are out of sync it will have a second real login screen.  The pre-boot authentication screen is skinned to look like the real login screen but it most certainly is not.  Using Pi-KVM you can attach to HDMI & KB/Mouse and the Pi-KVM is networked so you can load it's web page, login and manually login to the Mac Mini.  The servo solution is to physically press the power button.  Using a Pi-KVM with a server you could mount the Pi-KVM internally with a PCI slot cover passing cables in and out of a racked server.  Internally you can reach the power pins on the server motherboard.  Pi-KVM is useful when your server / PC / Mac doesn't have enterprise class BMC which allows for IPMI, iDRAC, iLO found on real servers.  The old Apple Xserves had iLO Lights-Out management.  But none of the modern Macs have the necessary BMC chips and remote management functionality of PC servers.  It would be nice to have that.  Companies like MacStadium are no-doubt developing internal solutions to solve the problem.  

Good luck actually sourcing RaspberryPi hardware there are severe shortages globally.  Seems some commercial vendors are buying up all the rPI's and they are being given priority by the manufacturer.

maltz

darkvader said:

maltz said:

At some point you have to ask if a row of Mac Minis are the right tools for the job...  probably a point well before this.  lol

Oh, it isn't.  But since Apple killed the Xserve, it's the only tool we've got.  VERY stupid move on Apple's part.

Honest question:  Why is ANY Mac the right tool for the job?  I'm not sure what server application is better handled by macOS than by Linux these days.

maltz

JamesBrickley said:

Good luck actually sourcing RaspberryPi hardware there are severe shortages globally.  Seems some commercial vendors are buying up all the rPI's and they are being given priority by the manufacturer.

That shortage is easing.  Even RPi4's are in stock all over the place (as I write this).  Adafruit has recently been getting rounds of stock that lasted for the better part of a week.

JamesBrickley

Good to hear on rPI4 stock.  Now if they only stocked the full line of rPI4 Compute Modules, I would be a happy camper. 

FYI, RaspberryPI will soon have competition as there are some some new Rockchip RK3588 SoC chips which are 8-core (Cortex-A76x4+ Cortex-A55x4) 64-bit CPU, capable of speeds up to 2.4 GHz and can handle 32GB of RAM.  PCIe Gen 3.

zimmie

JamesBrickley said:

The old Apple Xserves had iLO Lights-Out management.  But none of the modern Macs have the necessary BMC chips and remote management functionality of PC servers.  It would be nice to have that.

They actually do have an equivalent to a BMC, though Apple calls it an SMC. Also, all Macs with built in 10g network interfaces except the iMac Pro support lights out management over the 10g interface. This includes the Mac mini if you spend the $100 to get the 10g interface. Would be nice if they had a more standard way of interacting with it (Redfish!), but it's enough to manage the hardware after initial setup. It's also hard to mess up in a way which could leave the system open to attackers.

maltz said:

darkvader said:

maltz said:

At some point you have to ask if a row of Mac Minis are the right tools for the job...  probably a point well before this.  lol

Oh, it isn't.  But since Apple killed the Xserve, it's the only tool we've got.  VERY stupid move on Apple's part.

Honest question:  Why is ANY Mac the right tool for the job?  I'm not sure what server application is better handled by macOS than by Linux these days.

There are certain services which only run on macOS. Most notably, Xcode Server, which allows you to run build and test bots to do work submitted by developer workstations. UI testing in Xcode involves a piece of software operating the system like a blind person would. It moves the cursor around, actually clicks on things, and so on. When running a suite of UI tests, the system running the tests is unavailable for any other UI work, so people really like being able to push that work to a remote server.

Apple also provides a content caching service which runs on macOS and caches software updates, stuff from the store, and so on.

On a purely subjective note, I cannot stand Linux, and I'm of the opinion that any application would be better handled by macOS than by Linux. With the widespread adoption of systemd, pretty much every distribution is wildly unreliable. I would never run anything I care about on it. I'd go with a proper UNIX (BSD, illumos, etc.), then a UNIXy RTOS (Pike|QNX|seL4|VxWorks), then Windows then not running the service at all, then Linux if I had no other option.

BlueLightning

mayfly said:

Isn't always being powered on the purpose of servers?

In a large data center, following a major power outage, it is often more complicated.  You cannot power on 2,000+ servers running many applications at the same time.  The power-on current spike would be destructive (hopefully, it would trip breakers).  Certain services MUST be running before others will respond normally.  Some applications are more critical to plant or staff operations.  Usually, with a large number of servers that are not periodically power cycled, a number will fail during startup due to hardware issues.  Many of these installations have a combination of Windows, various flavors of Unix, several types of minicomputers, a few mainframes, and maybe a supercomputer or two.  Usually, there are network connections to regional data centers and smaller remote data centers.  If it is a shared facilities data center, multiple companies have equipment in each room of the data center, and each one cannot start everything at the same time.  

I've seen instances where it has taken days for everything to be repaired after a big failure.  Heck, I've seen it take days to rebuild a Windows server and configure software following failure of multiple disks in a RAID array.  I'm thinking of a time and attendance server for a Midwestern aviation manufacturing branch office.  Hundreds of folks had to log time on paper for several days.  

In the first case mentioned (large data center), following a direct lightning strike to a power line, the power distribution equipment failed (it was managing a triple redundant uninterruptible backup power supply).  The power distribution equipment was made by a subsidiary of the company whose equipment lost power due to the lightning strike.