[vcf-midatlantic] Monitor needed for museum

Jim Scheef js at sdf.org
Sat Aug 26 09:49:34 EDT 2017

Could I ask a question? How often does this happen? Ok, two questions... 
what happens when the power goes off? (No talk about how reliable the 
power is at IA.) Just pull the f%^&ing plug and reboot the Pi. It has a 
journaling file system and will check the file system if needed. Why all 
the fuss?
Occasionally it might be a good idea to make a copy of the uSD card as a 

On Wed, 23 Aug 2017, William Dudley via vcf-midatlantic wrote:

> Date: Wed, 23 Aug 2017 09:31:40 -0400
> From: William Dudley via vcf-midatlantic
>     <vcf-midatlantic at lists.vintagecomputerfederation.org>
> To: vcf-midatlantic <vcf-midatlantic at lists.vintagecomputerfederation.org>
> Cc: William Dudley <wfdudley at gmail.com>
> Subject: Re: [vcf-midatlantic] Monitor needed for museum
> We are currently trying to install the shutdown button and associated
> script, but couldn't install the script as we lost the ability to ssh into
> the pi. So we can't power it down properly, we can't edit config files, and
> we can't fix ssh without the monitor.
> Bill Dudley
> On Aug 23, 2017 8:30 AM, "Neil Cherry via vcf-midatlantic" <
> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>> On 08/22/2017 08:21 PM, David Ryskalczyk via vcf-midatlantic wrote:
>>> I'll make an EE guess here: When you unplug the DC side, the Pi is shut
>>> off relatively
>>> quickly so there is little room for bad writes to corrupt the card, or
>>> for the voltage
>>> to drop low enough for the CPU to execute random instructions but still
>>> high enough to
>>> run at all. When you unplug the AC side of the power adapter, the
>>> capacitance in the
>>> power supply causes a much slower drop-off which causes the CPU to
>>> execute random
>>> instructions, likely writing to the card.
>> I think the USB PS tend to be more inductive than capacitive.
>> My suggestions? Make the Linux setup as read-only as possible as that will
>>> minimize
>>> possibility of corruption, and of course, if the image contents are
>>> static, keep a copy
>>> of the image handy on a nearby PC. Constant writing will quickly kill the
>>> SD card
>>> anyway.
>> This will help, you can setup a share using either NFS or Samba (CIFS).
>> You can then write to that.
>> But there are some things that need to write to files. The OS part
>> of Linux generally doesn't need this but the applications (rsyslog,
>> email, etc) does and they also tend to try and write out logs. That's
>> a distribution issue.
>> Pulling power from the DC end (that part that plugs into the Pi directly)
>> is probably not a bad idea. But not until you've run the shutdown cmd.
>> So to properly shutdown the Pi, run the shutdown command or use Dave's
>> suggestion of the pushbutton solution. I like that one but protect the
>> button and don't make it a big red button that say don't push. People
>> will want to push it.
>> I'm sure there are more than a few of us with stories of idiots pushing
>> the emergency power off on mainframes.
>> --
>> Linux Home Automation         Neil Cherry       ncherry at linuxha.com
>> http://www.linuxha.com/                         Main site
>> http://linuxha.blogspot.com/                    My HA Blog
>> Author of:      Linux Smart Homes For Dummies

js at sdf.org
SDF Public Access UNIX System - http://sdf.lonestar.org

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