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Re: corruption during power loss



On Thu, Sep 14, 2000 at 11:51:01PM -0400, Michael Soulier wrote:

> 	So, have you had to reinstall packages? With RedHat/Mandrake, I
> would immediately do an rpm -Va to verify everything, but I quickly found
> out that several packages would complain about being broken even after a
> fresh install, so the information was useless. 

yeah rpm -V is largely useless. (rpm period is largely useless.. oops
flamebait ;p) 

> 	I'm still getting deeper into Debian's packaging tools. 

for verification there is debsums but not all packages come with md5
lists.  

> 	I tried running sync on a cronjob every hour, but it didn't help

you would have to run it more often then that, like every 1 or 2 minutes,
but that is not really a very good solution. 

> much. I never understood why Linux seemed so vulnerable to this. I've had
> the system crippled for hours with corrupt files while I reinstall
> packages. Not since installing Debian, but considering what you've said
> here, maybe I've been lucky.

the reason is linux uses filesystem caching extensivly, this GREATLY
improves filesystem speed but at the cost of reliability in the event
of power failures.  BSD tends to do caching much less and as a result
has a bit more reliability but at the cost of the filesystem being
slow as snot (comparing an OpenBSD box i have here to my GNU/Linux
boxen) BSD mounts the filesystems in sync mode rather then async like
linux does.  

BSD has been working on something in between called soft updates, i
tried it on my OpenBSD box and ended up with corrupted filesystems... 

if you want your linux filesystems to be safer and are willing to
accept the significant performance hit change defaults to
defaults,sync in /etc/fstab for your ext2 filesystems.  be prepared
for things like tar -x and rm -rf to take eons though.  (dpkg upgrades
take much longer too)  

your other option is using a Journeling filesystem such as Reiser or
ext3 (reiser i think is more mature at this point but still has some
serious limitations such as being unsuitable for use on /) 

everything is a tradeoff. 

-- 
Ethan Benson
http://www.alaska.net/~erbenson/

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