Why Power Failures Can Always Lead To Data Loss 456
bigsmoke writes "So, all your servers run on RAID. You back up religiously. You're even sure that your backups are recoverable. But do you also need a UPS? According to Halfgaar (on Slashdot before to promote better Linux backup practices), yes, usually you do. He argues that despite technological advancements such as file system journaling, power failures can still cause data loss in most setups."
Illiteracy (Score:5, Funny)
From TFA:
(DRAM needs to be refreshed constantly otherwise it will loose it's data)
Fly, little data! Be free!
can always lead to data loss? (Score:5, Funny)
Re:Well no shit, Sherlock (Score:5, Funny)
I don't know about you, but my servers run on the power of cotton candy and happy thoughts.
Re:Well no shit, Sherlock (Score:5, Funny)
I don't know about you, but my servers run on the power of cotton candy and happy thoughts.
As a former sysadmin, I would think that any machine reliant on 'happy thoughts' would be the most crash-prone system in the history of computing.
Re:Well no shit, Sherlock (Score:3, Funny)
if only there was some sort of law that covered the tendency of things that can go wrong to go wrong.
I hear Murphy might have one :)
Re:Well no shit, Sherlock (Score:5, Funny)
One of the first things that will happen, is that the memory DIMMs will no longer be refreshed properly (DRAM needs to be refreshed constantly otherwise it will loose it's data) and very rapidly, the memory will contain only garbage. The hard drives and DMA controller however, will run a bit longer; so if data is being written to disk, the DMA controller will keep reading data from memory, but it has no idea that this data is corrupted.
However, we've recently seen that RAM holds state well enough to preserve crypto keys thru a power cycle [hackaday.com]. This has very scary implications: the RAM knows what's happening, and behaves differently (loses data immediately on power-off or remembers it for several seconds) in order to cause the most difficulty for the owner of the machine.
Not only are computer components intelligent and self-aware, they're also out to get us!
Re:It happened to someone (Score:5, Funny)
Yes. My first reaction upon reading the summary was.. "Duh?" What, did they have it plugged into the wall before that? A UPS becomes MORE critical, not less, as the cost of hardware (RAID arrays are expensive) goes up.
Is this bring your kid to work day? (Score:5, Funny)
Ok, now everyone has something to give to your kid for the sysadmin-in-traning class.
For the rest of us... back to work, nothing here you didn't learn your first year.
For the poster... Shame shame... Turn in your card.
Re:Well no shit, Sherlock (Score:5, Funny)
My servers run on Electricity but the RAID controller has battery backed up RAM so any cached data will persist a power failure and the disks are in writethrough mode.
I like this setup, but please. Tell me more about this cotton candy technology? Is it superior.
Re:Not me! (Score:5, Funny)
If there's clouds in your server room, your server's probably been slashdotted and is on fire!
Carefully proofredded article (Score:3, Funny)
"3.2. (Ecrypted) file systems"
Please tell me more about these ecrypted file systems. Do they also do gurnalling?
Re:Illiteracy (Score:3, Funny)
Get off my lawn, you little bits!
no, that's not the scary thing (Score:3, Funny)
Re:Well no shit, Sherlock (Score:3, Funny)
We just need to get that guy that declared Pluto is no longer a planet to declare that electricity no longer causes data loss.
Side note: He also declared that north is no longer a direction, blue is no longer a color, and your sister is no longer a virgin.
Re:Well no shit, Sherlock (Score:5, Funny)
I can offer you a Happy Thought UPS. It's a box of puppies. Be careful though, it only has 500 puppy Amps of capacity.
Re:Well no shit, Sherlock (Score:5, Funny)
Your mom loves you and pays for the electricity. That doesn't mean that your servers run on love.
It can be done! (Score:3, Funny)
...If you're a Mac fanboy running a network of Apple computers. If anything goes wrong, it's an artistic expression and anyone who criticizes the problem is a closed-minded square who "doesn't get it." Then you sit back in self satisfaction listening to alternative pop, thinking about how hip and different and enlightened you are.
Happy thoughts power supply: Dead stable.
Linux networks can run on happy thoughts as well as long as you run on electricity during the setup and installation stages and then switch to happy thoughts once everything's running properly...you just have to make sure you never, ever run emacs, vi, or Gpaint.
Re:Well no shit, Sherlock (Score:5, Funny)
Except the server that runs http://youporn.com/ [youporn.com]
Re:Illiteracy (Score:1, Funny)
I don't know about you, but I don't want my precious data to be loose, gallivanting around with the wrong kind of crowd. I'm looking at you, float32.
Re:no, that's not the scary thing (Score:5, Funny)
its not worth loosing you're cool about grammer misteaks and etc.
Re:Well no shit, Sherlock (Score:4, Funny)
Ah, that's easy (Score:5, Funny)
All you need to do is have the grid power feed some high wattage light bulbs. And near the light bulbs is some solar cells. The output from the solar cells is used to charge batteries which feed an inverter that actually powers the computer. Of course there is some power loss in the conversion process, and you need to have some (ok, a lot), of the input power to the system commited towards running a cooling unit to keep things at a reasonable temperature. But the resulting device provides clean power with no possibility of any surges getting thru to the protected equipment.
Of course, if you go to this level of trouble for your power source, then I'd also suggest opto-isolating all signal lines to and from the server. And enclose the server in a well grounded faraday cage. And it wouldn't be a bad idea to have a dedicated comm link to a duplicate server located else where. Preferably on a different tectonic plate.
Re:Well no shit, Sherlock (Score:5, Funny)
Re:Mmmm! Puppies!!! (Score:5, Funny)
They wouldn't warranty it so I ended up putting a Triplite ISObar surge suppressor between it and the server in our test environment and it was in service for years after that.
Never trust any piece of equipment...
You mean like a Triplite ISObar surge suppressor?