Re: [PLUG] UPS shopping
Interesting I have a smaller 5000k Generac, gasoline powered also. But it's old-school with the generator output directly feeding single phase 240 power. It runs at 3600rpm and the armature is a 2 pole so the formula yields 60Hz Small generator power is actually -very- clean far cleaner than utility power as long as the load is constant. When the load changes the frequency fluctuates and that induces spikes and sags. Modern "home house" generators seem to run at a slower speed with little regulation and are double-conversion, the fluctuating AC output is rectified to DC then that feeds a sinewave power inverter. The rpm is considerably lower because an engine running at 3600 rpm puts out a lot of noise. Triplite Isobar power strips are the "gold standard" in power cleanup, supposedly. Ted -Original Message- From: PLUG On Behalf Of Dick Steffens Sent: Saturday, December 30, 2023 5:03 PM To: plug@lists.pdxlinux.org Subject: Re: [PLUG] UPS shopping On 12/30/23 16:00, Ted Mittelstaedt wrote: > The problem with generators is that the frequency is dependent on how > fast the rotor spins and the second you put an electrical load on A generator > you increase the magnetic field resistance to the armature and the generator > slows down. > > When the generator is the size of a barn at Bonneville Dam and the > armature weighs 10 tons and you turn on your coffee pot the massive > inertia in the generator armature will not slow measurably > > When it's your Champion generator the armature slows measurably and the > frequency then gets lower until the engine's governor gives it more fuel to > compensate then the frequency returns to normal. > That makes sense. The generator I used to have (I think it was a Generac) was gasoline powered. I got it when I worked for EC Company. It was stolen a number of years ago. I got the Champion because of the dual fuel feature. I never had a problem with using the UPS boxes with the Generac. It's not a big deal, since I don't have to have my computers running during power outages anymore. But if there is something I can use between the wall and the UPS that would clean up the generator's power, that would be useful. Thanks. -- Regards, Dick Steffens
Re: [PLUG] UPS shopping (pure sine ...)
Wrap about 20-30 turns of wire around one leg of the AC power line and connect both sides to a scope and you have an inductive powerline oscilloscope. Much safer than resistors and capacitors. Also: $32.00 off Amazon: MINIWARE Pocket Oscilloscope DS211, Portable Oscilloscope Mini Size Handheld, Built-in Rechargeable Battery, 1 Channel, 200Khz Bandwidth, Entry Level Oscilloscope for Beginner And it even comes with a probe Ted -Original Message- From: PLUG On Behalf Of Keith Lofstrom Sent: Saturday, December 30, 2023 5:52 PM To: Chuck Hast Cc: Portland Linux/Unix Group Subject: Re: [PLUG] UPS shopping (pure sine ...) Many laptops have some sort of stereo audio input jack. I can imagine a resistor+capacitor kludge that attenuates the "hot" and "neutral" legs of a power cord down to the stereo input levels. A program on the laptop captures hot and neutral voltage waveforms, differences them, and (somehow) uses the digitized audio signal to characterize the voltage waveform quality produced by the device the cord is plugged into. Perhaps logging the waveforms to disk on the laptop, for long term monitoring. Sub-sampling at 600 samples per second and 16 bit resolution, that is 40 gigabytes per year, more than enough to capture "rare but too-interesting" power glitches over time. If someone wants to write the program to do the differencing and logging, I can put together a few cord-and-resistor-and-stereo-plug kludges, and trade hardware for software. The result would be a portable setup for evaluating the waveforms produced by a UPS in service, or a candidate UPS in the store. Besides evaluating UPS waveforms and behavior, it might also be interesting to look for time correlations in power waveforms between different locations around the Portland area. An office in an industrial area might see subsecond line voltage sags when a nearby factory is arc welding. I can imagine those driving some computer power supplies and UPS units batty. Keith L. -- Keith Lofstrom kei...@keithl.com
Re: [PLUG] UPS shopping (pure sine ...)
Many laptops have some sort of stereo audio input jack. I can imagine a resistor+capacitor kludge that attenuates the "hot" and "neutral" legs of a power cord down to the stereo input levels. A program on the laptop captures hot and neutral voltage waveforms, differences them, and (somehow) uses the digitized audio signal to characterize the voltage waveform quality produced by the device the cord is plugged into. Perhaps logging the waveforms to disk on the laptop, for long term monitoring. Sub-sampling at 600 samples per second and 16 bit resolution, that is 40 gigabytes per year, more than enough to capture "rare but too-interesting" power glitches over time. If someone wants to write the program to do the differencing and logging, I can put together a few cord-and-resistor-and-stereo-plug kludges, and trade hardware for software. The result would be a portable setup for evaluating the waveforms produced by a UPS in service, or a candidate UPS in the store. Besides evaluating UPS waveforms and behavior, it might also be interesting to look for time correlations in power waveforms between different locations around the Portland area. An office in an industrial area might see subsecond line voltage sags when a nearby factory is arc welding. I can imagine those driving some computer power supplies and UPS units batty. Keith L. -- Keith Lofstrom kei...@keithl.com
Re: [PLUG] UPS shopping
On 12/30/23 16:00, Ted Mittelstaedt wrote: The problem with generators is that the frequency is dependent on how fast the rotor spins and the second you put an electrical load on A generator you increase the magnetic field resistance to the armature and the generator slows down. When the generator is the size of a barn at Bonneville Dam and the armature weighs 10 tons and you turn on your coffee pot the massive inertia in the generator armature will not slow measurably When it's your Champion generator the armature slows measurably and the frequency then gets lower until the engine's governor gives it more fuel to compensate then the frequency returns to normal. That makes sense. The generator I used to have (I think it was a Generac) was gasoline powered. I got it when I worked for EC Company. It was stolen a number of years ago. I got the Champion because of the dual fuel feature. I never had a problem with using the UPS boxes with the Generac. It's not a big deal, since I don't have to have my computers running during power outages anymore. But if there is something I can use between the wall and the UPS that would clean up the generator's power, that would be useful. Thanks. -- Regards, Dick Steffens
Re: [PLUG] UPS shopping
On 12/30/23 15:29, Chuck Hast wrote: I am not sure you would have to check on each manufacturer, the best ones are on line double conversion the power goes through the UPS, it is rectified, the battery floats on it and the DC feeds an inverter so that the load never sees mains power. The rest of them are some form of standby/offline UPS which switches to the battery backed inverter if there is a failure or sag of some sort on the power line. The better ones will have line filtering to clean up the trash that is sometimes called utility power, again your mileage may vary Google is you friend on this one. Most of the better "pure sine wave" units do quite well, Triplite was used heavily on the glass container inspection machines I worked on, some plants had their own gen stations and the power was "up and down" line wiese (voltage and frequency) those never seemed to go offline they just did their job. In the hospital labs we have been using Cyber Power, these UPS also appear to do the job, everywhere we have put equipment behind them we have had no more issues with DOA PSU's and logic modules. There is APC which is all over the place, my issue with them was mainly that was the go to by the BioMed folks and APC kept on selling them modified sine wave vice pure sine wave and we would continue to have issues. Why APC would sell them modified sine wave when we had told them that they needed pure sine wave I do not not but kind of left a bad note in my mind about APC. I have a lab that put in APC pure sine wave and they have had no issues with power since. So I think that as long as you do a bit of due diligence you are probably in good shape. Thanks. -- Regards, Dick Steffens
Re: [PLUG] UPS shopping
The problem with generators is that the frequency is dependent on how fast the rotor spins and the second you put an electrical load on A generator you increase the magnetic field resistance to the armature and the generator slows down. When the generator is the size of a barn at Bonneville Dam and the armature weighs 10 tons and you turn on your coffee pot the massive inertia in the generator armature will not slow measurably When it's your Champion generator the armature slows measurably and the frequency then gets lower until the engine's governor gives it more fuel to compensate then the frequency returns to normal. Ted -Original Message- From: PLUG On Behalf Of Dick Steffens Sent: Saturday, December 30, 2023 11:39 AM To: plug@lists.pdxlinux.org Subject: Re: [PLUG] UPS shopping On 12/30/23 09:30, Chuck Hast wrote: > Google 24v inverter there are boat loads of them for 24v PV systems. > Ranging from 300W on up. > https://www.amazon.com/24-volt-pure-sine-wave-inverter/s?k=24+volt+pur > e+sine+wave+inverter If you are planning on running computers and > whatnot get a sine wave inverter, many switched PSU's do not like > modified sine wave (weasel words actually modified SQUARE WAVE) they > will put up with it but shortens life. The prices have dropped > considerably on them, same for the pure sine wave UPS. How well do those units deal with poor quality power from an emergency generator? I have a Champi8on 100296 dual fuel generator. When I'm running it, my UPS boxes won't run. They reject the power from the generator. I'm guessing it's because it's not 60 HZ, but something close enough that it's good for all the rest of the appliances, but not the UPS boxes. -- Regards, Dick Steffens
Re: [PLUG] UPS shopping
APC BackUPS are modified sine wave and there is no issue with them and your garden variety Dell or HP desktop, but of course you are taking your chances with anything high quality on them. APC SmartUPSes are pure sine wave. They are more expensive. APC makes all of this very clear in their documentation. Select BackUPS and you get trash cheap UPS select SmartUPS and you get the real deal. The BioMed folks were blowing smoke up your ass, APC doesn't substitute one UPS for the other, the BioMed people were just skimming more $ off the top. As to why they sell modified sine wave in the first place, the reason is that most UPS buyers are dumb as a box of rocks and just want The Cheapest Thing and many of them are so dumb they can't even change a battery, I've had customers in the past that when a UPS stated beeping they would toss it and buy a new one from Office Depot. The UPS market got flooded with crappy UPSes it was not that long ago that ALL CyberPower UPSes were modified sine not true sine. APC was getting undercut so they responded to the flooding by crap UPSes with their own crap UPSes at the same price point Ted -Original Message- From: PLUG On Behalf Of Chuck Hast Sent: Saturday, December 30, 2023 3:30 PM To: Portland Linux/Unix Group Subject: Re: [PLUG] UPS shopping I am not sure you would have to check on each manufacturer, the best ones are on line double conversion the power goes through the UPS, it is rectified, the battery floats on it and the DC feeds an inverter so that the load never sees mains power. The rest of them are some form of standby/offline UPS which switches to the battery backed inverter if there is a failure or sag of some sort on the power line. The better ones will have line filtering to clean up the trash that is sometimes called utility power, again your mileage may vary Google is you friend on this one. Most of the better "pure sine wave" units do quite well, Triplite was used heavily on the glass container inspection machines I worked on, some plants had their own gen stations and the power was "up and down" line wiese (voltage and frequency) those never seemed to go offline they just did their job. In the hospital labs we have been using Cyber Power, these UPS also appear to do the job, everywhere we have put equipment behind them we have had no more issues with DOA PSU's and logic modules. There is APC which is all over the place, my issue with them was mainly that was the go to by the BioMed folks and APC kept on selling them modified sine wave vice pure sine wave and we would continue to have issues. Why APC would sell them modified sine wave when we had told them that they needed pure sine wave I do not not but kind of left a bad note in my mind about APC. I have a lab that put in APC pure sine wave and they have had no issues with power since. So I think that as long as you do a bit of due diligence you are probably in good shape. On Sat, Dec 30, 2023 at 1:39 PM Dick Steffens wrote: > On 12/30/23 09:30, Chuck Hast wrote: > > Google 24v inverter there are boat loads of them for 24v PV systems. > > Ranging from 300W on up. > > > https://www.amazon.com/24-volt-pure-sine-wave-inverter/s?k=24+volt+pur > e+sine+wave+inverter > > If you are planning on running computers and whatnot get a sine wave > > inverter, many switched PSU's do not like modified sine wave (weasel > > words actually modified SQUARE WAVE) they will put up with it but > > shortens life. The prices have dropped considerably on them, same > > for the pure sine wave UPS. > > How well do those units deal with poor quality power from an emergency > generator? I have a Champi8on 100296 dual fuel generator. When I'm > running it, my UPS boxes won't run. They reject the power from the > generator. I'm guessing it's because it's not 60 HZ, but something > close enough that it's good for all the rest of the appliances, but > not the UPS boxes. > > -- > Regards, > > Dick Steffens >
Re: [PLUG] UPS shopping
I am not sure you would have to check on each manufacturer, the best ones are on line double conversion the power goes through the UPS, it is rectified, the battery floats on it and the DC feeds an inverter so that the load never sees mains power. The rest of them are some form of standby/offline UPS which switches to the battery backed inverter if there is a failure or sag of some sort on the power line. The better ones will have line filtering to clean up the trash that is sometimes called utility power, again your mileage may vary Google is you friend on this one. Most of the better "pure sine wave" units do quite well, Triplite was used heavily on the glass container inspection machines I worked on, some plants had their own gen stations and the power was "up and down" line wiese (voltage and frequency) those never seemed to go offline they just did their job. In the hospital labs we have been using Cyber Power, these UPS also appear to do the job, everywhere we have put equipment behind them we have had no more issues with DOA PSU's and logic modules. There is APC which is all over the place, my issue with them was mainly that was the go to by the BioMed folks and APC kept on selling them modified sine wave vice pure sine wave and we would continue to have issues. Why APC would sell them modified sine wave when we had told them that they needed pure sine wave I do not not but kind of left a bad note in my mind about APC. I have a lab that put in APC pure sine wave and they have had no issues with power since. So I think that as long as you do a bit of due diligence you are probably in good shape. On Sat, Dec 30, 2023 at 1:39 PM Dick Steffens wrote: > On 12/30/23 09:30, Chuck Hast wrote: > > Google 24v inverter there are boat loads of them for 24v PV systems. > > Ranging from 300W on up. > > > https://www.amazon.com/24-volt-pure-sine-wave-inverter/s?k=24+volt+pure+sine+wave+inverter > > If you are planning on running computers > > and whatnot get a sine wave inverter, many switched PSU's do not like > > modified sine wave (weasel words actually modified SQUARE WAVE) > > they will put up with it but shortens life. The prices have dropped > > considerably on them, same for the pure sine wave UPS. > > How well do those units deal with poor quality power from an emergency > generator? I have a Champi8on 100296 dual fuel generator. When I'm > running it, my UPS boxes won't run. They reject the power from the > generator. I'm guessing it's because it's not 60 HZ, but something close > enough that it's good for all the rest of the appliances, but not the > UPS boxes. > > -- > Regards, > > Dick Steffens >
Re: [PLUG] Looking for some WiFi AP Security Advice
Thanks, MC_SEQUOIA for the explanation. My assumption was that HTTPS encrypts the messages between the client browser and server, so one cannot just eavesdrop on the messages back and forth to generate a map of how to intercept and change the messages. Of course, one would have to gain access to the private WiFi network created with the AP, protected by a 16 character password and MAC filter, first. My security strategy was to put up multiple barriers to make it an annoying project for the nefarious types. Aslo, our launches are 2-4 hours long at most, and then the passwords change for the next launch, and no Internet connection. If someone is good enough to get through 3 randomly generated 16 character passwords and a MAC white list in 3 hours with a laptop within 300 feet of the launch site, he/she deserves the honor of launching all the rockets! Good idea to check the DHCP client list periodically during the launch. The AP provides that as well as a way to deny an unknown connected device, if needed. Mark On Fri, Dec 29, 2023 at 2:38 PM MC_Sequoia wrote: > > > > "I want to set up some sort of secure connection between the cell phone > > > and the web site running on the Pi." > > > > > > This should be doable via a vpn client/server. A quick google search on > > > "raspberry pi cell phone vpn" returned this: > > > > > > Are you saying a VPN is needed along with the SSL, or as a replacement? > Why > > both, or why as a replacement? > > An SSL certificate enables a web site to use HTTPS and it also verifies > the website's domain authenticity through a certificate authority. This is > all more for end-user security and privacy. Self-signed certs are for > non-production enviros. > > This does provide end to end security for any and every connected device, > but with a VPN, you can restrict which ip addr(s) can connect only via the > vpn. But since, "It is not accessible to the Internet, as the AP is not > connected to the Internet this is all happening on a private ip network", > all of this is secure connection concern is irrelevant as no one outside of > the private ip net can access the launch web site. > > Yes, it's possible to spoof a mac address, forge ip packets, etc. And > curious tech savvy kids will be curious tech savvy kids, but you're talking > about a fairly serious amount of time, effort, knowledge, skill and tools > to pull this off. > > I'd suggest there are far more interesting internet things for those > curious tech savvy kids to hack & crack on and/or into. > > I walked away from a lucrative cybersecurity career a few decades ago > because my experience was that the whole industry was built on the idea of > scaring people to buy security products and services. Yes, there are very > real vulnerabilities, exploits, security concerns and bad actor > hacker/crackers but people fail to correctly asses the real risks, threats > and targets. > > If you setup a reasonably secure launch situation and some black hat > genius kid cracks it and launches the rocket on you, they gotta be close > enough to get onto the WiFi and not in mom's basement over the internet. > > You should also be able to monitor the devices in real time that are > connecting to the WiFi AP. If you're not familiar with this, either poke > around on the AP mmgmt. web site or look through the instruction manual for > mac table, ip table, arp table, connected devices, or the like. If you see > a new device that you don't know connect to the AP before the launch, don't > launch until you figure out what's going on and/or disconnect/block that > device. > > I hope that gives you a better understanding of this whole secure launch > concern and gives you some peace of mind. Cheers! >
Re: [PLUG] UPS shopping
On 12/30/23 09:30, Chuck Hast wrote: Google 24v inverter there are boat loads of them for 24v PV systems. Ranging from 300W on up. https://www.amazon.com/24-volt-pure-sine-wave-inverter/s?k=24+volt+pure+sine+wave+inverter If you are planning on running computers and whatnot get a sine wave inverter, many switched PSU's do not like modified sine wave (weasel words actually modified SQUARE WAVE) they will put up with it but shortens life. The prices have dropped considerably on them, same for the pure sine wave UPS. How well do those units deal with poor quality power from an emergency generator? I have a Champi8on 100296 dual fuel generator. When I'm running it, my UPS boxes won't run. They reject the power from the generator. I'm guessing it's because it's not 60 HZ, but something close enough that it's good for all the rest of the appliances, but not the UPS boxes. -- Regards, Dick Steffens
Re: [PLUG] UPS shopping - attention suspend?
No they won't since like most things there is still a need - it's just a need by professionals who know what the hell they are doing. So yeah, the El-Crapo BackUPSes that look like a messed up power strip with micro-sized batteries and no management ports that keep The PC up long enough for the user to realize "oh crap there's a power failure I better click shutdown" will disappear. Those shouldn't have ever Been on the market in the first place because the plain fact is that PCs today with users sitting behind them are nothing more than glorified Internet terminals and have no need for fancy caching filesystems that trash when they lose power unexpectedly. But the professional quality UPSes that have large enough batteries to actually hold the equipment up for a reasonable amount of time for an orderly shutdown - like 30 minutes or so - to take place, yes THOSE will still be around. They will be more expensive of course - but the cheap UPSes were pointless anyway since the real total cost of a UPS isn't the equipment it's the batteries you buy for it over the years. Ted -Original Message- From: PLUG On Behalf Of Keith Lofstrom Sent: Saturday, December 30, 2023 12:15 AM To: Russell Senior Cc: plug@lists.pdxlinux.org Subject: Re: [PLUG] UPS shopping - attention suspend? On Fri, Dec 29, 2023 at 02:36:00AM -0800, Russell Senior wrote: ... UPS ... > Does anyone have recent experience, either positive or negative, > and/or any advice on replacements. I'd consider a used older model. Since computation equals dodopaddle (er "smart phone") for most of My Fellow Americans, I suspect desktops with UPS support will eventually become hard to find. I bought my most recent UPS from a Craigslist seller ... and replaced the batteries with SLAs from Interstate All Battery Center. A Craigslist purchase trip is a chance to visit neighborhoods I haven't seen before. One of my long term goals is to play with a Tesla Powerwall. I hope the batteries in those are better tended and last longer than the batteries in a UPS. Perhaps they will all fail after Musk absconds to Mars with our warranty money. A nearer term goal is to replace all the hard drives in the house with Samsung terabyte SSDs. My test machines suspend to SSD in less than two seconds, and reboot in ten. I can imagine a multicore CPU and a Linux kernel that continuously copies checkpoint RAM images to SSD, so that after power resumes, the machine "comes back" to a state resembling what I was working on when the lights went out. In a well-designed suspend environment, I can "suspend my thoughts" until the power comes back - and I am reminded by my computer of what I was doing before the power glitch. I would like a similar reminder process for other interrupts - doorbell, phone calls, potty breaks, and commands from She Who Must Be Obeyed. Indeed, I would like Linux tools that facilitate "timeouts" for exercise, meditation, ordering my desk, whatever keeps me at maximum productivity and happiness. "Human interrupt and resume" is just another neglected aspect of larger processes that are only partly addressed by a UPS. Keith -- Keith Lofstrom kei...@keithl.com
Re: [PLUG] UPS shopping
Google 24v inverter there are boat loads of them for 24v PV systems. Ranging from 300W on up. https://www.amazon.com/24-volt-pure-sine-wave-inverter/s?k=24+volt+pure+sine+wave+inverter If you are planning on running computers and whatnot get a sine wave inverter, many switched PSU's do not like modified sine wave (weasel words actually modified SQUARE WAVE) they will put up with it but shortens life. The prices have dropped considerably on them, same for the pure sine wave UPS. https://www.amazon.com/s?k=sine+wave+ups=1M0L8EHMXA3Z8=sine+wave+ups%2Caps%2C101=nb_sb_noss_1 I used to service glass container inspection machines, I would catch the bottle plants replacing the sine wave UPS with modified sine wave, then they would call because the switching power supplies in the machine were dying, I would make a service visit and find those UPS, tell them to replace them with a sine wave UPS, THEN I would fix the power supply problem. Usually ended up doing the UPS my self also. I presently have the same issue in medical labs I service. Some of the Hospital BioMed folks seem to think that a UPS is a UPS, have one that has had 3 machines replaced due to modified sine wave ups. they finally put in a sine wave UPS, no more issues. On Fri, Dec 29, 2023 at 3:59 PM Neal wrote: > There are plenty of 24 volt input inverters available, typically for > commercial trucks. > > NealS >
Re: [PLUG] UPS shopping - attention suspend?
On Saturday, December 30th, 2023 at 12:15 AM, Keith Lofstrom wrote: > ... > > A nearer term goal is to replace all the hard drives in the > house with Samsung terabyte SSDs. My test machines suspend > to SSD in less than two seconds, and reboot in ten. > Suspend doesn't save to your SSD. You are describing Hibernate. Not a semantic difference, they are distinct processes as far as the OS and motherboard are concerned. > I can imagine a multicore CPU and a Linux kernel that > continuously copies checkpoint RAM images to SSD, so that > after power resumes, the machine "comes back" to a state > resembling what I was working on when the lights went out. > That's what Intel Optane memory was supposed to do, but it looks like they discontinued that product line. It was advertised as "persistent memory" which I assume means the data is stored in non-volatile cells, meaning power can be cut with no change to whatever is currently in RAM. > In a well-designed suspend environment, I can "suspend my > thoughts" until the power comes back - and I am reminded > by my computer of what I was doing before the power glitch. > I would like a similar reminder process for other > interrupts - doorbell, phone calls, potty breaks, and > commands from She Who Must Be Obeyed. Indeed, I would > like Linux tools that facilitate "timeouts" for exercise, > meditation, ordering my desk, whatever keeps me at maximum > productivity and happiness. > > "Human interrupt and resume" is just another neglected > aspect of larger processes that are only partly addressed > by a UPS. > Microsoft tried to implement this in Windows 8 as a feature called "Fast Start". They use a hibernation file that holds a representation of the data in RAM and then change the boot process of Windows to operate more like a Resume-from-Hibernate. 10 years later the feature is still complete trash. With Fast Start enabled Windows tends to thrash the SSD to such an extreme that 6Gbps SATA is unable to provide enough bandwidth when peforming other disk-intensive tasks. On high memory systems the hiberfile also balloons to absurd sizes since it needs to match everything in RAM. On top of all that they have a lot of edge cases regarding errors and whether not a given piece of data should be retained. IT departments often disable Fast Start via group policy since it tends to tear apart the Outlook OST/PST database. Office365 apps in general get stuck in weird states due to extremely high disk utilization. And don't even get me started on the way USB devices get lost over time because the hiberfile doesn't get updated when the USB controller randomly resets. Instead of wasting clock cycles maintaining realtime parity between the RAM and SSD we should try bringing the power-to-performance ratio down to the point where the hardware only consumes electricity when it performs a calculation. Maybe ask Intel why they discontinued persistent RAM? -Ben
Re: [PLUG] UPS shopping - attention suspend?
On Fri, Dec 29, 2023 at 02:36:00AM -0800, Russell Senior wrote: ... UPS ... > Does anyone have recent experience, either positive or negative, and/or > any advice on replacements. I'd consider a used older model. Since computation equals dodopaddle (er "smart phone") for most of My Fellow Americans, I suspect desktops with UPS support will eventually become hard to find. I bought my most recent UPS from a Craigslist seller ... and replaced the batteries with SLAs from Interstate All Battery Center. A Craigslist purchase trip is a chance to visit neighborhoods I haven't seen before. One of my long term goals is to play with a Tesla Powerwall. I hope the batteries in those are better tended and last longer than the batteries in a UPS. Perhaps they will all fail after Musk absconds to Mars with our warranty money. A nearer term goal is to replace all the hard drives in the house with Samsung terabyte SSDs. My test machines suspend to SSD in less than two seconds, and reboot in ten. I can imagine a multicore CPU and a Linux kernel that continuously copies checkpoint RAM images to SSD, so that after power resumes, the machine "comes back" to a state resembling what I was working on when the lights went out. In a well-designed suspend environment, I can "suspend my thoughts" until the power comes back - and I am reminded by my computer of what I was doing before the power glitch. I would like a similar reminder process for other interrupts - doorbell, phone calls, potty breaks, and commands from She Who Must Be Obeyed. Indeed, I would like Linux tools that facilitate "timeouts" for exercise, meditation, ordering my desk, whatever keeps me at maximum productivity and happiness. "Human interrupt and resume" is just another neglected aspect of larger processes that are only partly addressed by a UPS. Keith -- Keith Lofstrom kei...@keithl.com
