[mythtv-users] apc backup

[Mike Thomas]

On Mon, 21 Mar 2016 19:12:12 +0000
David Williams <mythtv_david at yahoo.com> wrote:
>  p { margin-bottom: 0.1in; line-height: 120%; }Gentlemen, thank
> youfor the time and effort spent in crafting such informative
> replies.This is valuable information and makes me wish I had posted
> prior toembarking upon what sounds like it may be a flawed strategy.
> My onlyexperience with battery backup is an aged, pre usb connection,
> APCunit I bought for a buck at the Habitat ReStore where I
> volunteer.With a cheap replacement battery it became the power source
> for aVOIP landline. We have my nearly 100 year old mother-in-law
> livingwith us and I need to maintain 911 service. To make a terrible
> pun Irun the modem, router and ATA-adapter through a centenarian
> apparatusto guard a centenarian. Its worked flawlessly for nearly
> three yearsthrough any number of outages and thus served as the
> impetus to use asimilar strategy for my MythTV box. The major
> takeawaysfor me are as follows: 1) The stringmetaphor makes the point
> about duration interval quite well. Niceturn of a phrase. 2) What a
> greatstory about APC's non-warrantee; catch-22 at its worst. I should
> havepurchased a better UPS. I supposed I was swayed by the price
> andsheer number of Amazon customer reviews. Thanks for the heads
> upabout the generator.

Dear David,

Do not fret. You will find your APC UPS just fine. This was the point
I made. The UPS is still going. The battery status information is all
to cock, but it was never designed to be reliable in the first place.
It's not a good UPS, but it will do the job. The faulty one I wrote
about is still going after fifteen plus years.

The only thing you need to remember is to check the batteries regularly
like so:

1. Do a backup. I can't stress this enough.
2. Shut down your operating system without turning off the computer.
   An example of this would be to reboot it but interrupt it at the
   boot menu. The purpose of this is to provide a representative
   electrical load yet not have the operating system running. That way
   you won't get disc corruption when the power goes out.
3. Turn off the mains feed to the UPS. It will run on battery.
4. Measure how long it takes to flatten the batteries. This is the
   run-time.
5. Write this down, perhaps on the front of the UPS or on the batteries.

A year or so later repeat the test. The run-time will be reduced
because the batteries will be tired. Keep repeating this year after year
until the run-time starts to make you feel uneasy. Buy new batteries.
Play safe: don't wait for the "battery failed" light to flash.

This is the belt-and-braces approach to living with a UPS. It is much
the same as practising a fire drill. It is good practice. I am sure
Google do something like this.

I expect you will get two or perhaps three years from one of those
mickey-mouse battery boilers, but I wouldn't be surprised if you got
just one year or five. There are a lot of variables.

You /can/ go to all the hassle of removing the batteries from the
enclosure but I really don't recommend it, because you must take
precautions to avoid short-circuits and electric shock. Batteries of
that size can be quite spectacular if they short out. I did it partly to
prove a point, and also because I have a lot of batteries to replace.
It was costing several hundred pounds a year.

The thing about UPSes is that everyone tells you how great theirs is.
When you ask "but have you actually had a power cut" most people say
no. On a similar level, way back in the stone age I had a car insured by
some company or another. When talking to an insurance broker on another
matter I mentioned this company. He said, "but have you ever tried to
make a claim?" It's the same point.

On the generator front, a typical generator /may/ work, but it may not.
The smaller the load on the UPS in proportion to the capacity of the
generator the more likely it is to work. Just don't be surprised if the
inrush current of the UPS when it goes back to mains is enough to trip
the generator itself. It can be quite high. It's not atrociously high,
but it is enough to do this. As a rule of thumb if you can lift the
generator it could be tripped by the UPS. Other items can do this too. I
have a small Sun workstation with a 120 Amp inrush current. If I ever
turn it on I plug it directly into the wall because it trips my UPS.

> Does “slice” mean separate hard drive and what is a development box?

A slice is another name for a partition. Drives generally get "sliced"
into different sections known as partitions or volumes rather than use
entire discs. Partition is generally the name given to "old-style"
slices, slices which you set up when you first install your operating
system. Volumes tend to be the name given to things which can be
re-sized or moved without hassle. But they are just names. I suggest
you read up on this:

https://en.wikipedia.org/wiki/Disk_partitioning
https://en.wikipedia.org/wiki/Logical_Disk_Manager
https://en.wikipedia.org/wiki/Logical_Volume_Manager_%28Linux%29
https://en.wikipedia.org/wiki/Booting
https://en.wikipedia.org/wiki/Linux_startup_process
https://en.wikipedia.org/wiki/SYSLINUX
https://en.wikipedia.org/wiki/GNU_GRUB
https://help.ubuntu.com/community/UbuntuDesktopLVM

Also see the man pages for fdisk, cfdisk, mkfs, and those for GNU GRUB,
but feel free to ask questions.

A development box is slang name for a computer where I do software
development work, programming in other words. The boxes I abuse the
most are those for operating system work.

> 3) I need to
> acquirepartitioning skills. I've always just accepted the default
> settingswhen loading Ubuntu which is the distro I use. If anyone
> knows of aresource I'd appreciate a quick and dirty reference or two.
> Dave 

I hope this helps,

Mike.