Had another friend lose a hard drive today without a proper backup.
Pain!
I now have at least 3 copies of everything with staggered backups to
different hardware. For the digital signage
software I
manage there are two copies on the servers locally and another copy in
the cloud on Amazon's S3 storage which is itself replicated multiple
times.
The basic concept that people need to use is "SHARED NOTHING".
RAID is NOT the answer to data security, it's a convenient recovery
mechanism for failed hard drives but if your data is on two drives
connected to the same RAID controller card on the same computer in
the same room you have plenty of opportunities to lose it all.
Backups should ROTATE. Backing up to the same location risks a failure
in the backup that could wipe both copies, or copy bad data over good
before the mistake is discovered. For really critical data I have a
daily backup, a weekly backup, and a monthly backup. I also have two
backup schedules, morning that copies to one set of drives on controller
A and an evening backup that copies to a different set of drives on a
different controller.
Digital Twin are an online representation of a real world object, a copy of its properties in the digital world and a way to send updated and commands to it. In effect I've been making them for years but now they have a trendy name.
Why automated learning is hard for a smart home. The perils of over-fitting, under-fitting and how the general unpredictable nature of life makes it hard to build a system that learns your behavior.
One way to reduce the volume of sensor data is to remove redundant points. In a system with timestamped data recorded on an irregular interval we can achieve this by removing co-linear points.
Home automation systems need to respond to events in the real world. Sometimes it's an analog value, sometimes it's binary, rarely is it clean and not susceptible to problems. Let's discuss some of the ways to convert these inputs into actions.
Another super useful function for handling sensor data and converting to probabilities is the logistic function 1/(1+e^-x). Using this you can easily map values onto a 0.0-1.0 probability range.
In a home automation system we often want to convert a measurement into a probability. The ATAN curve is one of my favorite curves for this as it's easy to map overything onto a 0.0-1.0 range.
Several years ago we did a major remodel. I did all of the finish electrical myself and supervised all of the rough-in electrical. I also put in all of the electrical system and water in our barn. I have opinions ...
