USB flash data rot

[covacat]

I have an old bootable stick.
After 8 years data has changed slightly, enough to panic at every boot (privileged instruction fault in kernel mode).
Changed mobo/memory/cpu and whatnot until i figured it out.
no fsck errors, no surface scan errors
the stick is only used for booting, no write/no flash wearing, so it just lost charge
i knew it could happen but never expected it
less than 0.1% of the data has changed

 

[SirDice]

less than 0.1% of the data has changed

It only has to have a couple of bits flipped in the "right" place to corrupt a file. With some files that's not so dramatic (a couple of wrong characters in a text file for example) but a few flipped bits in a binary executable or a kernel is a whole different ballgame.

 

[Geezer]

less than 0.1% of the data has changed

Throw it away!

 

[covacat]

well, the stick is still good, it probably has under 2G of data written to it in its lifetime
it just lost charge and data got corrupted

 

[grahamperrin]

no surface scan errors

Which utility, used how?

(Depending on what's used: a full scan might not reveal a latent problem.)

 

[eternal_noob]

I bet Lennart tried to install systemd. games/xlennart

 

[covacat]

Which utility, used how?

(Depending on what's used: a full scan might not reveal a latent problem.)

dd

 

[angry_vincent]

i rather prefer ddrescue tool instead of dd, exactly for rescuing data from problematic devices.

 

[grahamperrin]

dd

Thanks, used how?

Did you overwrite the entire device?

 

[covacat]

just read/scan
dd if=/dev/da0 of=/dev/null bs=64k
also fsck could not find any problem
the device is used just several times a year when the server boots

 

[hardworkingnewbie]

I bet Lennart tried to install systemd. games/xlennart

Wow, I still remember when Xbill was new - and now Xlennart? That's a very questionable honor he's achieved there!

 

[grahamperrin]

… fsck could not find any problem …

fsck_ffs(8) is unlikely to detect rotten data.

From the UFS chapter of a 2006 book on Solaris internals (I can't find anything similar and more recent for UFS in FreeBSD):



– not entirely without checksumming, but this is for a log. Not for data.

 

[Alain De Vos]

I bet Lennart tried to install systemd. games/xlennart

He's busy restarting a service which died for unknown reason.

 

[Alain De Vos]

PS, with zfs you can do an n-way mirror on one physical device with n partitions ...
That remains only the gptzfsboot vulnerable ?