One thing I've always wondered about is how the ECC is handled on a modern SSD with regards to data retention.
SSDs often have a data retention spec that basically defines how long you have until your bits start flipping, and it usually falls off a cliff w.r.t. temperature, which can make SSDs non-ideal for offline backups.
However, I've read that reading from the SSD periodically allows it to detect these errors. Some say that even keeping it just powered on is enough.
My question is, do SSDs run some sort of internal scrub while they're powered on? I don't think so, based off of some power consumption tests I've done.
Also, if they do detect an ECC error, will they actually re-write the block in question, or just correct it and return a successful IO, while leaving the compromised data still on the media?
IIRC, it periodically scans the blocks level metadata during lulls. Reads don't take much power but for some larger drives something like 20% of activity was towards maintenance and the guaranteed retention period without power was only something like 2-3 months.
Not surprised to see you on here. I was the guy who got into the discussion about the merits of single mode vs multi mode with a few of your friends on Facebook a while ago. I was in the multi mode camp mainly due to cost reasons whereas they were in the single mode camp for future proofing reasons.
That said, the cost gap between MM and SM optics today is much smaller especially for 10G (and for the fiber itself it seems to have even reversed), so single mode definitely makes more sense. For some reason, MM fiber is still widely deployed in certain niche use-cases though. Not quite sure why.
For example, I know that it's used on modern military jets for their 10GBASE-SR networks. I wonder if it has something to do with being able to repair terminations in the field? I know MM is pretty forgiving that way. Or maybe it's just another case of them adopting whatever was popular at that exact moment.
It was surprising the amount of AV related gear that was multimode specific! The cost differential has dropped so much now you can run either at low cost so if you have the space you can run both.
MM is easier to do mechanical splices on, and does seem to be overall less sensitive to damage. If your need is 10G and less than 300m it works well.
As an aside I ran a USB over fiber repeater that was multimode specific by accident I used a single mode fiber (same LC connector), and it worked perfectly.
You can attach a string to a foam ball/plunger type thing and then suck it through with a vacuum from the other side. Then, fix your wire to the string and pull it back in the other direction.
A plastic bag tied to pulling twine works really well and is less likely to get stuck than a ball or plunger. I always leave a length of twine in my conduits so I only have to use the vacuum method once.
Indeed the plastic bag trick works very very well in a lot of different use cases. I was able to pull twine over 500 feet with this technique while doing my driveway conduits.
I had about 50 feet and 270° of bends in some PVC conduits I'd buried under a section of yard. I'd gotten everything done and asked my wife to come help me get the poly string and then mule tape into the conduits. The poly line practically leapt into the conduit chasing the plastic bag. It was one of the greatest ratios between how hard I thought something might be and how hard it actually was.
Pulling a bit of twine through from my pool over to where I had installed my equipment pad went much the same way, and I was too dumb to think about using a plastic bag ;). Just stuffed a bit of twine in one and and left it loose, walked over to the other and and put a shop vac on it, and -whoosh- here came the string. Felt like cheating. It was only a small conduit, though, 3/4 inch, so it had pretty good airflow.
Another example is how garage door opener trip-beams work (the sensors that detect if something is in the way before lowering the door).
The transmitter and receiver are wired in parallel and connected to a power supply through a series resistor. When the receiver receives the signal from the transmitter, it pulls the supply voltage down, which then causes the transmitter to stop transmitting, which then causes the receiver to stop pulling the supply down, and the cycle continues. The end result is that if there's no obstruction, the supply voltage pulses and the system checks for this. If there's any other type of condition, the signal is either 0 or VCC. Basically, the system is designed so that false positives are extremely unlikely since that's the worst case scenario.
There's some capacitors in the transmitter/receiver to control the frequency.
Gas central heating boilers use something similar to control the gas solenoid - the solenoid is fed through a biggish capacitor, which has a diode and a capacitor to "smooth" the pulses from the microcontroller. If the microcontroller output latches itself on, the capacitor charges fully, there are no more pulses, and the solenoid drops out.
It’s fine for debug builds, but people should be aware that building with the address sanitizer enabled balloons the size of the executable and slows it down tremendously.
One should always measure to see if there is a noticeable slowdown or not.
That is what I have meant by "an extremely serious reason to do otherwise".
For many programs the speed is determined by things like the throughput or latency of accessing the main memory, or by I/O operations, or by interaction with an user, in which case the sanitize options have negligible influence on speed.
When necessary, they should be turned off only for specific well tested functions whose performance is limited by CPU computation in registers or in cache memory, and they should remain on for the rest of the program.
ASAN can easily slow your program by 100x or worse. Your bias should always be that its impact would not be acceptable in production. If you were willing to accept the cost of ASAN you should have simply chose a slower, safer language in the first place.
I’m not sure about that. Most cars can stop way faster than they can accelerate. The differences in force would be even more extreme for front wheel drive cars where the weight transfer allows for more grip on the front wheels during braking compared to accelerating or peeling out.
There were basically VPN services back in the day that would allow you to play Halo CE over the internet with strangers (the game would think it's on a LAN).
This was before Xbox live (Halo CE didn't support live AFAIK), then even afterwards for modded consoles that got banned from live.
XBConnect and Xlink Kai if memory serves me right, and I think if you got crafty you could use the likes of Hamachi.
At first it was just fun to play online Halo, then we started diving into the files and modding game types and weapons. The Xbox was such a fantastic console. As someone whom had several GameSharks, hackable is so much of the fun.
Me and my brother connected across the Atlantic to a "server/game" on the east coast, I wanna say upstate New York maybe?
Fantastic bunch of dudes, the main one had a fat fiber pipe so 16 player matches were smooth.
We played alot of "party" style game modes (zombies and duck hunt type games)
And some modded game modes came about that were fantastic fun.
Cat and mouse on the Coagulation map, where the cats were in wraiths, and everyone could spawn in their own warthog to drive using the plasma pistol, wraiths were honour bound to not fire, boost only until the last minute, and hogs had to not hide in bases/caves.
There was also Tremors, with ghosts as the graboids.
XBConnect was solid enough that I could rig a network switch to my desktop, and both our consoles could work with it.
Lost touch with them after Halo 3 when system link above ~20ms got "blocked" :(
I had a couple really long running matches on XBConnect. One in particular I remember was team shotguns on Lockout (Halo 2); the points-to-win was something absurd like 10,000 and it was lasted all day. People would come and go as the day went on. I took a nap, went outside, came back, picked up the controller, and got right back into it. Really not something, as far as I'm aware, you can do now on, e.g., Halo MCC over Xbox Live. Good times!
Between soldering LED's into the controller ports, making the xbox logo in the center of the console light up and the xecuter3 modchip, I had so much fun modding the OG xbox. I was first exposed to IRC and FTP through the Xbox modding community. I thought my multi-colored boot screen[1] was the coolest thing ever. Anyone else make the golden warthog skin[2] for halo 2?!
My main high school income was from modding Xboxes. It was all just local kids but one of my friend’s brothers worked for a celebrity and one of the Xboxes was apparently featured on MTV’s Cribs so I called it quits.
Our modded Xbox was done by my dad's friend at his work. Somehow I stumbled upon a halo modding forum and learned what I needed to do the most basic mods: ftp to pull the halo2 map files off of the box, using the signing tools to allow for modded maps to be played, and using a hex editor and modding tools to make the smg shoot tank rounds!
Secureboot style integrity systems that only boot into envs with ubiquitous signature validation and have lots of hardware protections to maintain that in the face of other bugs.
And even before that we had services like Kali which would emulate a local network but over the internet for LAN only games. I remember using it to play MechWarrior 2.. poorly, the networking code was never designed to handle large latencies that you would get over modem.
I remember that, but I can't remember the name of it. I used it to play Counter-Strike online on my original Xbox before I had a PC capable of playing modern (at the time) games. It was well-populated enough that I could always find plenty of games. Godsend for a kid that couldn't afford the monthly fee for Live.
Corded electric mowers are very rare in the USA. I live in a suburban neighborhood in the North East and have never seen one in my life. I see some battery powered ones though.
I wonder if it’s due to our outlets being 120V? We’d be limited to less than 2.5 HP with a normal outlet, whereas gas push mowers typically have engines in the 5-7 HP range.
Wow. I had no idea that was something that could happen. I would have expected you to wake up before damaging yourself like that - sort of like falling asleep in the bath tub.
I've heard it called Drunk's Palsy (long term effects) or Saturday Night Palsy (shorter term, less severe). Falling asleep in such a way that circulation is cut off to an area, causing damage that normally your body would move to prevent. Drugs and alcohol impede that input to the brain so you don't toss and turn as much, I guess.
One day last year I noticed I couldn't feel part of my leg after my wife had sat in my lap for a few minutes earlier in the night. It freaked me out as I still had no feeling in it the next day. The doctor told me it was pinched and would regrow over time. It took about a month to get full feeling back.
The phenomenon is well known to bondage affectionados who know what they’re doing. They will regularly get pinched nerves and lose sensation, which is an absolute no-go to just «power through». Communication is essential, and many learn to subtly shift to stop the pinching without completely stopping the scene.
Accidents are really frightening, and can happen due to inexperience, carelessness, lack of communication or just really getting caught up in the monent.
All I gather from their description is that they basically just get a "feel" for it. That's why so many people choose to follow the two negative quarter thing - it's objective and clearly defined, but maybe less accurate (particularly in cases like now where unemployment is still really low).
You're approaching it from the standpoint that it's an exact science, but it's more of a social science and you can't really pin down exact specifics, but only best guesses. Unfortunately (and I fell into this camp for a long time) many people see economics and see the mathematical models and assume that it must be scientific or precise, but the marketing campaign to legitimize economics unfortunately confused many of us into that misconception.
It's helpful to think of economics as a field under the branch of political science, which itself isn't very scientific.
I like to think of it as not really one or the other, but as both. It’s like a venn-diagram intersection of finance and sociology. Some elements of economics are purely quantifiable, and some elements are purely human.
Both of those are up to the consensus of the group of economists. They regularly talk about it with each other and compare with historical data mostly. Keep in mind economics is a social science, not exact science.
It would strike me more as "feeling it out", but they are not in a rush to announce it is or is not a recession until they have a better feel. Everyone seems to be rushing to call it a recession as early as possible. The economist I heard talking had a "wait and see" attitude on the podcast which was refreshing to hear.
I'd say listen to the economists that are actually apart of the group and form your own opinion. I didn't get that impression personally. Although I'm sure there is some impact.
Economics is a social science. It is probably the most data-driven of the set, but it is inescapably human, and therefore ultimately comes down to judgment.
SSDs often have a data retention spec that basically defines how long you have until your bits start flipping, and it usually falls off a cliff w.r.t. temperature, which can make SSDs non-ideal for offline backups.
However, I've read that reading from the SSD periodically allows it to detect these errors. Some say that even keeping it just powered on is enough.
My question is, do SSDs run some sort of internal scrub while they're powered on? I don't think so, based off of some power consumption tests I've done.
Also, if they do detect an ECC error, will they actually re-write the block in question, or just correct it and return a successful IO, while leaving the compromised data still on the media?