[mythtv-users] apc backup

[Simon Hobson]

Mike Thomas <mt3 at pfw.demon.co.uk> wrote:

> Contrary to Simon, I prefer ext4 for everything

Well using EXT3 is in large part because I haven't set much up for some time - and my Myth system was setup back when EXT4 was in the "well it's still a bit new" category !

> Add to that the following laughable problems (not all of which are
> peculiar to APC UPSes):

Yes we come across these all the time.

> - They are incompatible with generators. They switch off, on, off, on,
>  off, on until they blow a fuse. They create huge voltage spikes
>  whilst doing this.

There's a setting to widen the mains voltage tolerance. We've successfully run them off generators - once this has been changed. Well actually it just means the load runs off the genny and the UPS recharges it's battery. A couple of years ago one of our customers had  several pre-announced mains outages - whole day jobs. Several times I've been out with my small genny to keep their servers going (for remote users). Now they've fitted a mains input and changeover switch by the meter and share next door's genny (a bit 80kVA job they use for running electrically powered diggers if there's no mains available) and just carry on as normal.



Stephen P Villano <stephen.p.villano at gmail.com> wrote:

> Or even an APC Symmetra, which is a far cry from a BackUPS unit. The old
> adage is a truism, you get what you pay for.

Ah, the Symmetra. I could write a book on what's wrong with the Symmetra LX from the users POV. But having said that, ours at work was run in a far from ideal environment and lasted a few years. Plus, it was bought cheap off a certain online auction site, and APC replaced the comms module in the external battery cab FOC even though it was well outside of warranty. One by one the power conversion modules "just stopped", and the battery modules have a non-resettable status stored in a memory chip so when you fit new cells it will carry on showing them as faulty.

It replaced a system (BPC Power Tower) we bought brand new from a UK manufacturer (though not UK manufacturers if you get the difference) which had several serious flaws. They considered having a significant error in measured load (it didn't register anything below 2A !) as OK as it's only an indication not a lab grade measuring instrument ! They outright lied about the SNMP data it would provide. And it's battery test actually didn't - it simply moved **some** of the load to battery so the only real way to test if it would actually work off battery was to switch the mains off (I don't think so !).
It also had no battery monitoring other than bus voltage - so when a cell goes bad (nominal 120V strings like the Symmetra) it has no way of detecting the increased current in one string and just carries on "charging" until the string finally cooks itself and one morning you walk into the office to the familiar sulphurous smell.