One issue that can arise for home stakers is power outages. In addition to incurring inactivity penalties, if the execution client is not shut down gracefully the database can be corrupted, requiring a full resync. Because of this, using an uninterruptible power supply (UPS) is a must for a good home staking setup. Below I provide a couple of different options:
-
A cost effective basic setup which provides for graceful shutdown and automatic restart
-
A more advanced setup that provides extended run time on backup power
Basic Setup - UPS with Monitoring for Automatic Shutdown
The diagram below shows a basic UPS setup. This is quite cost effective and is enough for most home stakers. It provides protection from database corruption by gracefully shutting down the staking machine when UPS backup power is exhausted, and automatically restarts the machine when power is restored.
-
Backup Power - Both the modem/router and staking computer are powered by the UPS so that validator duties can continue during the power outage until the UPS battery is exhausted.
-
Auto Shutdown - The staking computer has a USB connection to the UPS to monitor its status. A daemon running on the staking computer is configured to gracefully shut down the machine when the UPS battery level reaches a certain threshold. (CyberPower provides free Power Panel software which works on linux machines.)
-
Auto Restart - Staking machine BIOS is configured to boot the machine when power comes back on. (Here’s a help article for intel machines.)
Basic Setup + Additional Battery Backup
A consumer grade UPS is relatively inexpensive but offers a relatively short period of backup power. (My 600VA UPS will power my NUC staking machine and internet modem/router for about 2 hours.) For those who want to keep their validators running through longer outages, there are a couple of options:
-
Bigger UPS - Enterprise grade UPS systems can offer much more battery backup, but the extra run time comes at a high cost
-
Lithium-ion Battery - An external battery with an inverter to power the UPS can provide a lot of extra run time and is a much more cost effective option than a super-sized UPS.
The diagram below shows the basic setup with an additional backup battery. Rather than plugging the UPS into an AC power outlet directly, the UPS is powered by a large deep cycle Li-ion battery and inverter combination as depicted below.
An enhancement to the setup above is to add an Automatic Transfer Switch (ATS) to avoid using the battery and inverter 24/7 to power the UPS. An ATS has two power inputs, primary and backup. It will provide power from the primary input under normal conditions, and switch to the backup when primary power is lost. With the setup as shown below, the inverter and battery are not used until backup power is needed.
Backup Power Runtime Calculation
So how much runtime can be expected with this setup in an outage? It depends on the capacity of the battery (or batteries connected in parallel), and the power consumption of the staking computer and internet modem/router. The formula to calculate this is:
Backup Time (in hours) = Battery Capacity (in Ah) X Input voltage (V) / Total Load (in Watts)
This works out to be 28.3 hours for my setup, not including any additional time I may get from the UPS battery. My staking machine (NUC) uses about 15W, and the modem/router uses 27.4W for a total of 42.4W. The battery is rated at 100Ah at 12V. (100 x 12 / 42.4 = 28.3)
Cost
Below is a list of the components I used for the full setup depicted above, along with the current price. (I have no affiliation with the suppliers.) Your results may vary of course.
-
CyberPower 900VA UPS $100
-
Total $955
I hope some of my fellow Ethereum node operators find this writeup to be helpful. If you have constructive feedback or questions, drop me a DM on Twitter @asymrisk1.