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Smart power strips - why?

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EightBySix:
I get that a software power down via the front end might be attractive, but apart from that, what's the difference between a connection to a power switch to the pc which then powers everything else down via a smart strip, and just killing the main power....

bullrees:

--- Quote from: EightBySix on December 14, 2011, 07:35:36 pm ---I get that a software power down via the front end might be attractive, but apart from that, what's the difference between a connection to a power switch to the pc which then powers everything else down via a smart strip, and just killing the main power....

--- End quote ---

There is the myth that if you don't shut down your computer properly via software it will cause problems but I don't think that's the case here. I'm speculating but if people want to boot right into the front end and it be seamless from power on you have to shut down windows correctly to prevent getting the "start windows in safe mode" or check disk stuff. Just a guess though.

MonMotha:
It's not really a myth. Data loss due to improper shut down is possible.  Modern journaled filesystems (Windows NTFS, Linux ext3/4, OS X HFS+, etc.) are pretty good about not blowing up the whole filesystem, but you could still lose any newly written data (and possibly the old version, as well, for overwrites).  A proper shutdown ensures this will never happen.  Note that older filesystems like FAT, ext2, etc. found on Win98 and ancient versions of Linux (before about 2000) are not journaled and can totally blow up if you hard power the system.  I've experienced this, and it sucks; you basically get to start over from scratch.

There are ways around this.  If you can ensure that the data on the drive never actually needs to change (i.e. it should start up in the same state every time), you can use a copy-on-write (COW) ramdisk arrangement.  Windows supports this using something called the "enhanced write filter" (EWF) that's included with the XP embedded toolkit and can be installed on a standard copy of XP Pro or Win7.  On Linux, this can be done using unionfs and a tmpfs.  I don't know how to do it on OSX, but it's probably possible.  If you have a small amount of non-critical data that needs to be persistant across reboots like a high score table, you can just locate those on another partition that doesn't have this on it.  Then worst case, if the whole thing goes poof, you lose your high scores.

DOS is a bit of an odd beast in this.  DOS doesn't do any caching at all, so you can hard power it as long as it's not actively doing anything.  You just have to make sure it's not actively writing to the disk (which can be a bit hard unless you fully exit back to the command prompt), otherwise the above "you might lose everything" precautions apply.  I can't really say I would recommend anybody build a new system using DOS unless they have a very, very good reason to, though.

Now, I've hard powered modern Windows and Linux systems for years with few issues.  As long as there's not a bunch of write activity, and a typical MAME system wouldn't have much, you're usually just fine.  However, there's always the possibility of Murphy rearing his ugly head.

Most commercial PC embedded products like arcade games, cash registers, etc. use the above-mentioned COW system like EWF to make sure that they're reliable in the presence of the inevitable hard power off situations that people expect from an "appliance" type system.  Many embedded Linux systems just run the whole thing out of a ramdisk that's loaded at startup or run the entire root filesystem readonly, but neither is an option on Windows (though you can approximate the former with Windows PE).

Of course, you can also just ensure that you "properly" shut down the PC system.  That will ensure you have no problems, but it can be inconvenient.

IronBuddha:
I use one for the exact reasons Nephasth mentioned. But I also bought one for my entertainment system for the main reasons why it was invented, which is to save some energy and money while my TV is shut off.

wizkid32:
Personally, I plan on just using a regular power strip and leaving the speakers, USB hub, et al on.

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