What should I do after a power failure?
Fred Sloniker
I know that powering the system off manually is a Bad Thing (tm), but I live in Cowville, so a black-out is always a possibility. It's also possible that my mom would turn the computer off out of ignorance, despite my attempts to educate her on computer no-nos. What do I need to do, if anything, to make sure my hard drive isn't hosed after a power-off? Is there an equivalent to the Windows Scandisk-after-crash thing?
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Kent West
>Hey, everybody. First-time Linux user here (well, sort of; I've struggled before with getting either Debian or SuSE installed, unsuccessfully). So far, I like what I've seen of Debian (mostly installation screens and documentation); not only do I like the actual freeness of it (SuSE, for instance, wouldn't give me any avenues for getting help or ways to upgrade my version without me paying them cash), but the documentation is friendlier, I think. I'm sure once my 12-hour download finishes that I'll have more questions, but for now, I just want to ask this:
>
>I know that powering the system off manually is a Bad Thing (tm), but I live in Cowville, so a black-out is always a possibility. It's also possible that my mom would turn the computer off out of ignorance, despite my attempts to educate her on computer no-nos. What do I need to do, if anything, to make sure my hard drive isn't hosed after a power-off? Is there an equivalent to the Windows Scandisk-after-crash thing?
>
>
>
fsck ~= scandisk; it'll probably run automatically if the system detects
an improper shutdown (drives weren't unmounted, etc)
You might also want to convert your file systems to ext3 (from ext2), or
an even more robust system. But converting to ext3 is easy, and offers a
pretty good compromise between safety/speed/convenience.
Kent
Timmo
an accidental power interruption and the box was totally hosed from it.
I've had one occur recently, and the file system checker did it's thing but
things were never quite right again. I ended up deleting and recreating
everything relating to the user that was logged in to KDE at the time.
So I'm also very curious about what happens, aside from the file system
which seems to be able to fix itself.
Noah L. Meyerhans
> I know that powering the system off manually is a Bad Thing (tm), but
> I live in Cowville, so a black-out is always a possibility. It's also
> possible that my mom would turn the computer off out of ignorance,
> despite my attempts to educate her on computer no-nos. What do I need
> to do, if anything, to make sure my hard drive isn't hosed after a
> power-off? Is there an equivalent to the Windows Scandisk-after-crash
> thing?
It's called fsck and it will run automatically when your computer gets
turned back on. There are other situations where you may need to run it
manually. It's get a man page, so "man fsck" will get you docs on it.
To make it easier on your filesystem, you probably want to use the newer
ext3 filesystem on your machine, rather than the old (and still default)
ext2. ext3 contains some extra logic to help maintain filesystem
consistancy on the disk at all times, which means that the fs is less
likely to be in a fragile state when the power goes away.
noah
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Dennis van Dok
> About 2 years ago, the last time I tried to get linux off the ground, I had
> an accidental power interruption and the box was totally hosed from it.
>
> I've had one occur recently, and the file system checker did it's thing but
> things were never quite right again. I ended up deleting and recreating
> everything relating to the user that was logged in to KDE at the time.
KDE, Gnome and session-keeping stuff in general don't deal well with
such brute interruptions. Not even a synchronised, journaling file system
can help you here.
>
> So I'm also very curious about what happens, aside from the file system
> which seems to be able to fix itself.
Software that deals with important data--such as mail handlers, databases
and such--are programmed with some care to make sure there is never a
state in which a power failure could cause data loss. So much can't be said
of all software.
It's like a monkey swinging from tree to tree--he always makes sure he
holds on to at least two lianas at a time.
I find it hard even to file a bugreport against Gnome for messing with
my window placements. It's hopeless.
--Dennis van Dok
nate
> So I'm also very curious about what happens, aside from the file system
> which seems to be able to fix itself.
this entirely depends on how the system lost power. If the system
lost power in a clean way, that being something such as a UPS cut
the power(e.g. going from 110V to 0V in 1ms or something), probably
not much if any damage to the hardware.
If the system is hooked directly to the outlet, any number of things
can happen. The power can slowly drag down, perhaps it drops to 80V
and hovers there, the computer may be in half-on state(depending on
the power supply), the power could spike before it drops off. Some
power outages I've noticed the input voltage on the UPSs still have
some voltage(sometimes less then 1 volt). Other outages the voltage
drops to 0.0V and stays there.
severe damage can occur in spikes(some of which a surge supressor
can prevent), and brownouts(very hard to detect without some sort
of meter, most UPSs beep if they detect a brownout).
I protect my home network with an APC SmartUPS 1000RM, a Cyberpower
1500AVR, and a Cyberpower 900AVR. all are connected to NUT which
emails me when theres problems(and logs to my syslog server).
I do like APC's powerchute though, it has a lot of nice features and
shows a lot more detail on the UPS(if its a SmartUPS at least).
nate
nate
> on the subject of journalled filesystems. i've been using reiserfs. i've
> noticed that invariably, some files will get corrupted,
> especially logs. they end up looking like 2 files spliced together.
what kernel and what version of resier? any software raid?
I've had tons of crashes with reiser, though I've never noticed any
curroption or data loss. Doesn't mean there isn't any, but in a year and
a half, haven't noticed even a bit of trouble.
running 2.2.19 with reiserfs 3.5.32 according to version.c at least I
think my version is newer then that, perhaps 3.5.35 or something, maybe
version.c didn't get updated.
nate
David Z Maze
> About 2 years ago, the last time I tried to get linux off the ground, I had
> an accidental power interruption and the box was totally hosed from it.
>
> I've had one occur recently, and the file system checker did it's thing but
> things were never quite right again. I ended up deleting and recreating
> everything relating to the user that was logged in to KDE at the time.
If you have frequent problems of this sort, one thing that I've found
helpful is to install the debsums package, and configure it to
generate md5sums files for any packages that don't already come with
them. Then, when my hard drive eats itself[1], I run 'debsums -s' and
reinstall any packages with corrupted files or broken md5sums files.
[1] Not that this happens on my laptop, uh, about once a week or
anything...
--
David Maze dm...@debian.org http://people.debian.org/~dmaze/
"Theoretical politics is interesting. Politicking should be illegal."
-- Abra Mitchell
Russell
> Hey, everybody. First-time Linux user here (well, sort of; I've struggled
before with getting either Debian or SuSE installed, unsuccessfully). So far,
I like what I've seen of Debian (mostly installation screens and documentation);
not only do I like the actual freeness of it (SuSE, for instance, wouldn't give
me any avenues for getting help or ways to upgrade my version without me paying
them cash), but the documentation is friendlier, I think. I'm sure once my 12-hour
download finishes that I'll have more questions, but for now, I just want to ask this:
>
> I know that powering the system off manually is a Bad Thing (tm), but I live in
Cowville, so a black-out is always a possibility. It's also possible that my mom
would turn the computer off out of ignorance, despite my attempts to educate her on
computer no-nos. What do I need to do, if anything, to make sure my hard drive isn't
hosed after a power-off? Is there an equivalent to the Windows Scandisk-after-crash thing?
>
Use ext3 because it's more crashproof.
info sync
I'd make a cron job that does a sync every 5s or 1min or whatever.
Paul Johnson
coming through as one giant line each.
On Wed, Nov 27, 2002 at 11:08:49AM -0800, Fred Sloniker wrote:
> I know that powering the system off manually is a Bad Thing (tm),
> but I live in Cowville, so a black-out is always a possibility.
> It's also possible that my mom would turn the computer off out of
> ignorance, despite my attempts to educate her on computer no-nos.
> What do I need to do, if anything, to make sure my hard drive isn't
> hosed after a power-off? Is there an equivalent to the Windows
> Scandisk-after-crash thing?
fsck will run on any filesystem not unmounted cleanly. Killing power
is not unmounting cleanly.
Alternatively, you can run ext3 for a filesystem, which gives you the
ease of dealing with ext2 filesystems, but gives you journaling,
making it much harder to corrupt the filesystem due to improper
poweroff, disk removal, or other dirty unmounting.
--
.''`. Baloo <ba...@ursine.dyndns.org>
: :' : proud Debian admin and user
`. `'`
`- Debian - when you have better things to do than to fix a system
Chris Lale
Fred Sloniker wrote:
> Hey, everybody. First-time Linux user here (well, sort of; I've struggled before with getting either Debian or SuSE installed, unsuccessfully). So far, I like what I've seen of Debian (mostly installation screens and documentation); not only do I like the actual freeness of it (SuSE, for instance, wouldn't give me any avenues for getting help or ways to upgrade my version without me paying them cash), but the documentation is friendlier, I think. I'm sure once my 12-hour download finishes that I'll have more questions, but for now, I just want to ask this:
>
> I know that powering the system off manually is a Bad Thing (tm), but I live in Cowville, so a black-out is always a possibility. It's also possible that my mom would turn the computer off out of ignorance, despite my attempts to educate her on computer no-nos. What do I need to do, if anything, to make sure my hard drive isn't hosed after a power-off? Is there an equivalent to the Windows Scandisk-after-crash thing?
>
Be prepared! Consider making bit-image backups on second hard disc using
Partimage. You can choose to have the images split into 650 Mb files
for burning onto CD.
If you have a large enough second hard disc consider Rdiff-backup which
is a cross between mirroring and incremental backup.
Cheers,
Chris.
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