poweroff corrupted disk

farmer.ro · Apprentice Joined: 20 Aug 2016 Posts: 179

yesterday my entire neighborhood had a power shut down, resulting in my Gentoo box having a instant power loss.

i had a corrupted disk before, and now i am scared that this power off might have broken my Gentoo system, but how can i know for sure nothing is broken?

snkmoorthy · Guru Joined: 19 Nov 2002 Posts: 376

Boot with https://www.system-rescue-cd.org/SystemRescueCd_Homepage and check.

farmer.ro · Apprentice Joined: 20 Aug 2016 Posts: 179

how long would that take?

NeddySeagoon · Posted: Mon Oct 31, 2016 9:33 am Post subject:

farmer.ro,

You can't check.
All the filesystem checking tools do is verify that the filesystem is self consistent. They say nothing about user data.

For example, if a data block in the middle of a video was altered it would not be detected.
You need to run an application like tripwire with maintained off system checksums to detect changes in user data.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

farmer.ro · Apprentice Joined: 20 Aug 2016 Posts: 179

after having the sudden power loss from last night resulting my Gentoo Box been shutdown, what should i do?

how can i make sure that the next time i have a build failure or any other form of failure on my system is not caused by a possible corrupted file system?

do i need to dd my disk and start building Gentoo from scratch again? or can i just continue using my computer?

Akkara · Posted: Mon Oct 31, 2016 10:14 am Post subject:

Usually the only things that would get corrupted are files that are being written to, or that have been recently written if the buffers haven't been flushed completely out yet. "Completely" means not only to the disk, but the disk itself might be buffering things up (especially a SSD) and that needs to finish too.

Rebuilding it all is one way to make sure it's all good. You'll either succeed, in which case if there had been corruption it will have been quietly fixed. An error in a non-build-essential package can be paved over that way. Or it will fail, if important packages like gcc are corrupt, or if your distfiles are corrupt (in which case removing and re-fetching will help). Odds are they aren't, unless you just happened to be emerging that as the power failed (and more than emerge - it had to be installing at that moment, if not at worst you'll get a corrupted sandbox).

This will ensure the system is good. There's no way of ensuring your own data, except by checking against backups; or having a file of known checksums as Neddy suggested; or - possibly - using a RAID, but a RAID can still have the problem that data in memory got corrupted first.
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farmer.ro · Apprentice Joined: 20 Aug 2016 Posts: 179

i had open ssl handshake error this morning: https://forums.gentoo.org/viewtopic-t-1053889.html

portage complained about some dist files for missing or something, but i am not sure if it is because of the power loss.

i had a corrupted hard disk before where portage itself was broken and mods on the Gentoo confirmed it was because of a corrupted hard disk.

all i would like to know, can i continue using my computer, or do i need to rebuild Gentoo from scratch?

the next time i get a build failure or any other error i might not be able to fix it due to a possible corrupted disk, and have to rebuild anyway.

C5ace · Posted: Tue Nov 01, 2016 10:20 am Post subject:

I solved my power failure ans lightning strike problems by investing some money in a online UPS to protect my desktop, server, router and phone system.

Zucca · Posted: Tue Nov 01, 2016 10:24 am Post subject: