Bristol Digest, Vol 556, Issue 3

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Today's Topics:

1. Meeting this weekend (matthew_symes@yahoo.co.uk)
2. Re: Is it harder on computer to stay powered up, or hibernate
often? (Jamie Lokier)
3. Raspberry pi controlling remote power sockets -
views/experience? (Peter Hemmings)


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Message: 1
Date: Tue, 24 Jun 2014 00:50:15 +0100
From: "matthew_symes@yahoo.co.uk" <matthew_symes@yahoo.co.uk>
To: "bristol@mailman.lug.org.uk" <bristol@mailman.lug.org.uk>
Subject: [bristol] Meeting this weekend
Message-ID:
<1403567415.42630.YahooMailAndroidMobile@web133204.mail.ir2.yahoo.com>
Content-Type: text/plain; charset="utf-8"

Hi all,

I've been lurking on the mailing list for a number of years now and i finally intend to get to the meeting this weekend.

I'm a big linux fan as, for me, it put the fun back into computing.

Currently running arch and xububtu on the lappy that also boots a bunch of live isos using grub2. I have a number of usb sticks that multiboot various linux distros using syslinux (and grub4dos).

Server is runnng 12.04 but may be running 14.04 by the weekend. Among other things, it pxe boots a whole bunch of different isos from luppy, dsl and slitaz to breakin.

Router runs dd-wrt and i'm currently in the process of setting up a cross compiling environment to recompile iptables for a friends router with dd-wrt on it because of the iptables connlimit bug in dd-wrt vesion of iptables that his routet has.

I also have recently got a pi and intend to install openelec on it. If i'm impressed with it, i'll get another for a project.

So i'm a big linux fan and looking forward to meeting some of you.

Matt.

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Message: 2
Date: Tue, 24 Jun 2014 09:33:39 +0100
From: Jamie Lokier <jamie@shareable.org>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Cc: Winnie.lacesso@bristol.ac.uk
Subject: Re: [bristol] Is it harder on computer to stay powered up, or
hibernate often?
Message-ID: <20140624083338.GT23603@jl-vm1.vm.bytemark.co.uk>
Content-Type: text/plain; charset=us-ascii

Chris wrote:
> On 23 June 2014 08:26:06 BST, Winnie Lacesso <Winnie.Lacesso@bristol.ac.uk> wrote:
> >
> >Dear *,
> >
> >Is it harder on one's home computer to stay powered up, or to
> >hibernate often, like hibernate it before goto work & resume when
> >get home, & also hibernate it before one retires for night & resume
> >computer in morning?
> >
> >I tend to think it's harder on the hardware to hibernate
> >frequently. What is others' experience?
> >
>
> No bad experience doing this yet.
>
> Speculation:
> I would expect that given the life of a HDD and the underutilisation
> of the swap partition on a modern system that you wouldn't see any
> bad effect for a very long time (I'm thinking decades). Maybe
> there's an effect for SSD, though this is probably mitigated at the
> firmware level.

Long ago I was told that repeatedly turning the HDD on and off
stressed the bearing, wearing it down faster, and this was why servers
should be left on continuously. And that laptop HDDs were designed to
handle this better because they are spun down more often, even if they
are switched on but inactive.

I don't know if that's an old myth or not.

If true, it won't apply to SSD, and hopefully the SSD firmware is not
stupid enough to corrupt data from going to sleep (but you never
know).

Ssome people complained when Linux started spinning down laptop HDDs
much too aggressively while idle. E.g.

https://bugs.launchpad.net/ubuntu/+source/acpi-support/+bug/59695

But that's talking about the harmful effect of spinning down the HDD
about every minute, so is probably completely irrelevant.

It mentions in the bug description that 15 load cycles per hour
"provides a life expectancy of over four years, which is reasonable
for a hard disk."

-- Jamie



------------------------------

Message: 3
Date: Tue, 24 Jun 2014 12:23:59 +0100
From: Peter Hemmings <peter@hemmings.eclipse.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: [bristol] Raspberry pi controlling remote power sockets -
views/experience?
Message-ID: <53A95FCF.2030700@hemmings.eclipse.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed


Hi,

I have to go upstairs to switch on my router on when I use anything
downstairs on the WiFi lan. I have lots of other stuff connected via an
8 way socket so need to simplify things and, ideally put the router on
another socket. The problem is I keep forgetting to switch off the the
sockets and have been looking into an interesting use of a pi and some
remote sockets so I can control everything plus other stuff from the pi!

Before going further, has anyone tried to something like this, if so
what has been your experience!?

I found these:

http://www.maplin.co.uk/p/remote-controlled-mains-sockets-5-pack-n38hn

but I think Morrisons/Asda were doing them a lot cheaper!

There are quite a few posts/blogs on this but essentially you sniff the
data sent by the remote that comes with the sockets, then use the Pi to
replay this data, hopefully triggering the socket to turn on or off!

I have seen Audacity used on the output of a cheap 433khz receiver to
decode the 4 signals from the r/c transmitter.

Seems an interesting project!

I have also read there is a limitation on the pi's output rate (sorry
may be wrong terminology!).


Regards

--
Peter H



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