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by jerrm
Wed Aug 29, 2018 1:08 am
Forum: General discussion
Topic: Is it really true, that the RPi runs faster when booting from a good USB Stick?
Replies: 31
Views: 2989

Re: Is it really true, that the RPi runs faster when booting from a good USB Stick?

USB only Pi's will lose about 10% of their CPU unless you implement one of the fixes mentioned in this thread: https://www.raspberrypi.org/forums/view ... 8&t=211912
by jerrm
Sat Aug 25, 2018 3:41 pm
Forum: General discussion
Topic: LAMP server
Replies: 14
Views: 748

Re: LAMP server

DougieLawson, If we're talking about bad programming practices then "SELECT *" is one of the worst. It leaves a ticking timebomb that will bite later. Consider what happens when you add an extra column to your table. You will break your code. I have heard you say that "SELECT *" is bad practice her...
by jerrm
Thu Jul 26, 2018 11:17 pm
Forum: HATs and other add-ons
Topic: ETA for Official POE Hat for 3B+
Replies: 64
Views: 8965

Re: ETA for Official POE Hat for 3B+

There is a 3rd part PoE HAT shipping. See viewtopic.php?p=1313975#p1313587
by jerrm
Tue Jul 24, 2018 4:27 am
Forum: Beginners
Topic: Know how a process has been started
Replies: 2
Views: 178

Re: Know how a process has been started

PID 589 is execution of sudo
PID 605 is execution of python by sudo (PPID is 589)

Anything launched from rc.local is already running as root. sudo is not needed (unless you want to run as a non-root user).
by jerrm
Thu Jul 12, 2018 9:00 pm
Forum: Troubleshooting
Topic: Netboot issues with mod 3 B+
Replies: 14
Views: 1973

Re: Netboot issues with mod 3 B+

Fixed! RPi3B+ boots with dnsmasq running on my mac ... so probably I messed up something on the production setup and wrongly conclude that there is problem with the bootrom - my apologies guys. If no SD card is installed, fix the mmc rescan CPU utilization issue - see: https://www.raspberrypi.org/f...
by jerrm
Thu Jul 12, 2018 8:57 pm
Forum: Troubleshooting
Topic: rpi3b+ and booting with a USB Key : impossible???
Replies: 2
Views: 174

Re: rpi3b+ and booting with a USB Key : impossible???

USB booting is enable by default on the 3B+. Burn the image to the USB drive exactly as you would with the SD card. It should boot up. If it doesn't boot, try another brand drive. Not all USB drives work. Anything I've tried from Verbatim will not boot. Other non-Verbatim flash drives I've tried boo...
by jerrm
Thu Jul 12, 2018 8:17 pm
Forum: General discussion
Topic: 25% of SD's corrupted
Replies: 7
Views: 696

Re: 25% of SD's corrupted

I don't really subscribe to the idea that a "read only" SD card is safe from corruption from power issues. If bad power is causing damage to the drives at a hardware level, then my gut says USB will be better. If it is simply file system (not hardware) corruption from an unclean shutdown, I doubt th...
by jerrm
Wed Jul 11, 2018 10:39 pm
Forum: General discussion
Topic: Thinking of writing a technical FAQ
Replies: 53
Views: 2407

Re: Thinking of writing a technical FAQ

I'd already done some of the suggestions above, so perhaps best if I link to the work in progress so you can see where I am at. Not copy edited yet. https://github.com/raspberrypi/documentation/blob/JamesH65-technical-faq/technical-faq.md The CPU utilization issue for net/usb booted Pis should be d...
by jerrm
Wed Jul 11, 2018 10:15 pm
Forum: General discussion
Topic: Setting a static IP address from SD card before boot
Replies: 20
Views: 6625

Re: Setting a static IP address from SD card before boot

For the sake of completeness, there is actually a 4th way to edit files on the root partition of a Pi SD card, but this method requires $. You can install an extFS driver for Mac that will allow it read and write to Linux ext partitions: https://www.paragon-software.com/home/extfs-mac/ Unfortunatle...
by jerrm
Sat Jul 07, 2018 2:58 pm
Forum: Advanced users
Topic: How to encrypt USB Ports in raspberry pi?
Replies: 6
Views: 701

Re: How to encrypt USB Ports in raspberry pi?

If there is physical access to the Pi, the only secure way is to encrypt the root file system and the USB drive. If the Pi reboots, you will have to enter a passphrase, it won't come up automatically. If the root system isn't secure, there is nothing to prevent the bad actor from pulling the SD card...
by jerrm
Sat Jul 07, 2018 1:55 pm
Forum: General programming discussion
Topic: Script for controlling RPi via Windows 10 PC automatically
Replies: 4
Views: 1335

Re: Script for controlling RPi via Windows 10 PC automatically

andyx wrote:
Sat Jul 07, 2018 10:48 am
Fantastic, this is what i was looking for - plink, I have forgotten it's name.
OpenSSH is included in Win10 as of the spring update. No need for plink if Windows is currrent.
by jerrm
Thu Jul 05, 2018 9:48 pm
Forum: Troubleshooting
Topic: raspbian strench lite no homepage
Replies: 4
Views: 330

Re: raspbian strench lite no homepage

if there is no raspberry desktop, how can I use that? If you need a GUI desktop, then Lite is not the right tool for you. If you can get your job one with the console or via SSH, then Lite is fully functional. All of my Pi's but one run Lite, but they are all headless and perform server-like duties...
by jerrm
Wed Jul 04, 2018 4:59 pm
Forum: Advanced users
Topic: Net booting RPi 3B+ constantly reading SD card
Replies: 3
Views: 288

Re: Net booting RPi 3B+ constantly reading SD card

Are you sure the system tries to access the SD? The SD polling when no card is present is well established, but completely undocumented. What's worse, all that polling for the missing SD card wastes 10% of your CPU. Again, the Pi folks seem to think the wasted CPU isn't worth documenting. Luckily t...
by jerrm
Mon Jul 02, 2018 4:48 pm
Forum: Beginners
Topic: Experience with specific PoE
Replies: 6
Views: 297

Re: Experience with specific PoE

The biggest issue is can it actually supply 5V 2.4A as advertised ?? Maybe it is worth waiting for the Official PoE HAT ?? https://www.raspberrypi.org/products/poe-hat/ The RPF POE HATdoesn't really exist yet, still stuck in the "Coming Soon" vapor. There is one 3rd party 3B+ POE HAT that does exis...
by jerrm
Mon Jul 02, 2018 3:10 pm
Forum: Beginners
Topic: Experience with specific PoE
Replies: 6
Views: 297

Re: Experience with specific PoE

The above is not quite right. If the output is truly as advertised , any Pi, including the 3B+ should work just fine with the linked splitter. Since the splitter only supports 100mbps, the 3B+ will only connect at 100mbps, not 1gbps. Only the user knows if that matters. Biggest caveat is the listing...
by jerrm
Fri Jun 29, 2018 7:02 pm
Forum: Troubleshooting
Topic: Broken microSD card slot and USB boooting not working
Replies: 11
Views: 528

Re: Broken microSD card slot and USB boooting not working

Also - if it works, make sure to deploy the empty SD card CPU utilization fix.
by jerrm
Fri Jun 29, 2018 7:00 pm
Forum: Troubleshooting
Topic: Broken microSD card slot and USB boooting not working
Replies: 11
Views: 528

Re: Broken microSD card slot and USB boooting

OK, I'll try with some other USB from different manufactors, thanks for the information Verbatim USB flash seems consistently bad for Pi booting. Tried several models of differing models/capacities/ages and none worked. Everything else I've tried seems to work, but specifically I've used Samsung FI...
by jerrm
Fri Jun 29, 2018 2:13 pm
Forum: Troubleshooting
Topic: Broken microSD card slot and USB boooting not working
Replies: 11
Views: 528

Re: Broken microSD card slot and USB boooting

Sasso0101 wrote:
Fri Jun 29, 2018 1:52 pm
One pin broke of from the board and I think that is irreparable or very hard to fix, so I was searching of alternative solutions to boot. Maybe is just my USB that is too slow (I have an 8gb Verbatim store N Go)?
Try another USB drive. Verbatim drives have never booted for me on the Pi.
by jerrm
Fri Jun 29, 2018 1:01 pm
Forum: Troubleshooting
Topic: High CPU usage when booting from USB
Replies: 35
Views: 4059

Re: High CPU usage when booting from USB

The updated sdtweak.dtbo is now in the official Raspbian as of the 06-27-2018 release and will be installed with your preferred apt commands. No rpi-update needed.
by jerrm
Thu Jun 28, 2018 1:52 pm
Forum: General discussion
Topic: Pi3 - USB boot
Replies: 43
Views: 18028

Re: Pi3 - USB boot

I notice my pi runs about 5 degrees hotter celsius when running over USB than off the microSD. Perhaps i need to run it off a powered hub to take the strain off the pi. Temp may be due to the fact the Pi is constantly at 10% CPU utilization when there is no SD card. A rather important detail none o...
by jerrm
Fri Jun 22, 2018 10:43 pm
Forum: Beginners
Topic: Raspberry pi 3 b and the industry
Replies: 18
Views: 871

Re: Raspberry pi 3 b and the industry

I have also asked this question on reddit and someone said that for these kind of things, industries use devices such as cRIO from National Instruments, but RPI would be used as a prototyping instrument. That would be enough to justify my academic project to use RPi. For academic purposes, I don't ...
by jerrm
Wed Jun 13, 2018 4:39 pm
Forum: Troubleshooting
Topic: Raspberry Pi 3 B+ lockups
Replies: 464
Views: 47204

Re: Raspberry Pi 3 B+ lockups

I have a 3B+ tested by @PhilE which he confirmed has no RAM issues. Have you tried the 450 option? I don't think it's a matter of RAM not running at 500 but of timing/interaction issues with other subsystems. Pi3B+ is not an option for us until there is a pretty clear "we know the issue and here is...
by jerrm
Wed Jun 13, 2018 3:55 pm
Forum: General discussion
Topic: Raspberry Pi 3 Model B+ clusters
Replies: 35
Views: 4285

Re: Raspberry Pi 3 Model B+ clusters

A Pi would definitely be I/O bound. A Pi won't come close to 41MB/s with a straight "cp" command

I doubt it would be an exaggeration that it would take 5+ Pis all working in parallel just to average the output you'd get from a single x86 sub-$100 refurb PC.
by jerrm
Tue Jun 12, 2018 6:54 pm
Forum: Advanced users
Topic: Daisy chaining ethernet with raspberry pi.
Replies: 11
Views: 1100

Re: Daisy chaining ethernet with raspberry pi.

Anyone old enough to remember daisy chained networks (the good old days of 10base-2) will have plenty of stories about them going wrong - any break in the chain meant the whole segment went down (as it was no longer properly terminated) and you got lots of unhappy people. Finding the one connection...
by jerrm
Tue Jun 12, 2018 4:14 pm
Forum: Advanced users
Topic: Daisy chaining ethernet with raspberry pi.
Replies: 11
Views: 1100

Re: Daisy chaining ethernet with raspberry pi.

You could add a USB adapter to each Pi and bridge the interfaces, effectively daisy chaining. Pretty simple to do, but I wouldn't recommend it. If a pi in the middle is down/locked up/turned off, everything downstream would lose connectivity. Strategically adding some switches along the line so that...

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