Flash storage topics [LWN.net]

Flash storage topics

Posted Jun 8, 2018 15:33 UTC (Fri) by zlynx (guest, #2285)
In reply to: Flash storage topics by nix
Parent article: Flash storage topics

I suppose?

In my personal experience, while I have had UPS batteries go bad, which just happens every so many years, I haven't had a UPS actually fail. I have had more computer power supplies fail.

And as for utility power, I don't understand how the UK could possibly be as reliable as you say. Perhaps I'm used to more spread out rural areas of Colorado, but with power lines on poles combined with extremely high winds (tornadoes sometimes) and lightning, and heavy wet snow, well, power is just going to go out every now and then. I really don't see how maintenance could help.

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Flash storage topics

Posted Jun 8, 2018 15:50 UTC (Fri) by karkhaz (subscriber, #99844) [Link] (7 responses)

The weather is a lot more temperate in the UK than it is in Colorado. Neither tornadoes nor hurricanes form here, and as for heavy snow---well, people freaked out last winter when London was belaboured with five glorious centimeters of it, most years we get none. Personally, I've not in my entire life seen a single power outage in London.

Flash storage topics

Posted Jun 8, 2018 16:42 UTC (Fri) by excors (subscriber, #95769) [Link] (1 responses)

https://www.ukpowernetworks.co.uk/power-cut/map has a handy map - right now it appears to be reporting 4 unplanned power cuts in London, affecting about 82 customers, so outages are not totally unheard of. (Unfortunately they don't seem to have an obvious way to see historical data. My vague memories are of somewhere between maybe 0.5 and 2 outages per year, living in places outside London.)

Flash storage topics

Posted Jun 14, 2018 17:30 UTC (Thu) by Wol (subscriber, #4433) [Link]

Admittedly I have only lived on the outskirts of London for pretty much my entire life, but there are - over that entire period - only three power outages that I can remember.

After heavy rain, there was a landslip at a chalk pit that took out the local substation.

At work, some robbers tried to blow their way into a bank vault, but in the process took out a major electricity supply cable.

Some thieves tried to steal a copper power line (250KVA, I think) and took out a small town.

Things like brownouts are pretty much unknown.

So yes, in Britain MOST people MOST of the time never experience a problem. The only people who will see any need for a UPS are people who live near an industrial area where their neighbours are dirtying the supply. Outside of that, supply is both good and reliable, and short outages are almost unknown. If there's a problem, it's either with the house supply itself, or in the cases I've mentioned above it's a major but localised problem - at one day, the first problem was the one rectified the quickest of the above three. The second took a week, while the third left many homes without power for days ...

Cheers,
Wol

Flash storage topics

Posted Jun 9, 2018 10:53 UTC (Sat) by anselm (subscriber, #2796) [Link] (4 responses)

Neither tornadoes nor hurricanes form here

The UK Met Office would beg to disagree on tornadoes:

Around 30 tornadoes a year are reported in the UK. These are typically small and short-lived, but can cause structural damage if they pass over built-up areas.

Hurricanes in a literal sense don't occur in the UK a lot, but sometimes the “tail end” of a hurricane can end up in Britain as a destructive storm, like Hurricane Ophelia in October, 2017.

Given that overhead power lines are fairly common at least in rural areas of the UK, it would not be in the least surprising that storms (including hurricane remnants and tornadoes) caused occasional power outages.

Flash storage topics

Posted Jun 9, 2018 12:39 UTC (Sat) by mpr22 (subscriber, #60784) [Link] (3 responses)

The UK has the most tornadoes per year of any country in Europe, and more tornadoes per square kilometre per year than any country in the world except the Netherlands. (I think it might even have more tornadoes per square kilometre per year than the region of the USA known as "Tornado Alley".)

Flash storage topics

Posted Jun 9, 2018 13:44 UTC (Sat) by karkhaz (subscriber, #99844) [Link] (2 responses)

Cheers for these facts, I must admit to not knowing them despite enthusiastically following the hurricane season in the US.

One thing that occurs to me, though, is that the sources for "highest number of tornadoes recorded per area" seem to have very population densities (Bangladesh is mentioned often, and the Netherlands and UK have the highest and third-highest densities of all the non-tiny European nations). This may be the reason that the reported numbers are so high for these countries: people are a lot more likely to see a tornado, even if it is too weak to cause significant damage, than in rural Tornado Alley. This is compounded by the fact that tornadoes are difficult to observe directly using radar, so tornado reports mostly come from people who have seen the tornado first-hand. And higher population densities lead to more frequent infrastructure that could suffer from noticeable damage, e.g. power lines, train tracks, etc.

Also I wonder if people being acclimatized to huge tornadoes in Tornado Alley leads to people reporting less of the smaller ones: a relatively benign tornado that would have somebody in the UK scrambling to phone the Met Office might just be ignored by their cousin over the pond.

Flash storage topics

Posted Jun 12, 2018 6:14 UTC (Tue) by k8to (guest, #15413) [Link] (1 responses)

I wonder what the standards are for what qualifies as a tornado.

In the United States northeast growing up, we had a number of minor twisters that no one thought to label "tornado". If it only uprooted 30 trees or so, it was "just a twister".

Flash storage topics

Posted Jun 12, 2018 6:34 UTC (Tue) by mpr22 (subscriber, #60784) [Link]

Wikipedia tells me that to qualify as a tornado, a weather phenomenon must involve a rotating wind column, reaching from ground level to the base of the overhead clouds, with surface wind speeds in excess of 40 mph (64 km/h).

Flash storage topics

Posted Jun 8, 2018 17:47 UTC (Fri) by nix (subscriber, #2304) [Link]

The power lines are only on poles in the UK in rural areas (villages and smaller): elsewhere they are usually underground and immune to most weather-related failures. Local stepdown transformers are not per-house, but cover a few blocks (so are much larger, much more expensive, and correspondingly much more *reliable*: they very rarely fail, and usually survive even direct lightning strikes). Every significant power station is required to be able to restart under its own steam, too, so we don't have cascading failures where big chunks of the grid go offline and can't come back on because they themselves need grid power.

Long-distance high-voltage cross-country lines and lines leaving rural power stations *are* up in the air, but it takes a hell of a lot of wind to knock down one of *those* monster pylons (again, it more or less never happens unless a tree falls on the lines, and they are usually routed away from trees for exactly that reason). It does happen, but because these are high-voltage lines there is almost always fallback from elsewhere in the grid if one is hit, unless there has been a *major* storm and numerous of them have been taken out at once. (Again, this affects major conurbations essentially never: distant rural Scotland, or single small towns that might have only one or two incoming lines, sure, but nothing larger.)

I am unhappy with the current state of the UK power network. I've had two flickers in the last decade, and checking my supplier's logs I see one five-minute outage! This is awful: in the decades of the 1990s and 2000s I had none at all. It's hard to justify a UPS with reliability like that. (Note: in the same time window we had a half-*day* water outage, when a farmer drove a plough through a 6in supply pipe and de-watered half the town...)

Flash storage topics

Posted Jun 28, 2018 11:32 UTC (Thu) by jospoortvliet (guest, #33164) [Link] (1 responses)

In most of north-west Europe powerlines are underground so power outages happen at most once every few years...

Flash storage topics

Posted Jul 7, 2018 19:53 UTC (Sat) by nix (subscriber, #2304) [Link]

In rural, particularly forested, parts of North Europe, the one-step-up-from-domestic local power lines come in overhead (because they have to, because running a power line under fifty miles of forest to serve a hamlet of twenty houses is ridiculous). When the trees grow and it snows hard enough (or gloopily enough), the power can go down and stay down for days or even weeks while kilometres of line are restrung. However, unlike in Puerto Rico -- or 1998 Auckland! -- it does not go down for months.