magic sysrq keys functionality

[Matthias Andree]

Scott Long <scottl at freebsd.org> writes:

> On Mon, 26 Jul 2004, Brian Fundakowski Feldman wrote:

>> SoftUpdates guarantess that your file systems will not get corrupt.

> This isn't entirely correct.  Softupdates guarantees that you won't get
> corruption due to metadata pointing to invalid or stale data blocks.
> That's not the same as guaranteeing that there won't be any corruption.
> Write caching on the drive combined with an in-opportune power loss or
> other failure can easily leave you with corrupt or incomplete metadata
> and/or data blocks.

I've had a SCS HDD lock up (1997 Micropolis 4345WS showing its age and
bad interaction with an Adaptec 2940UW Pro[*]) while softdep was writing
to the drive and suffered *SEVERE* file system corruption, which tore
down my /var/db/pkg and other stuff.

[*] The same adaptor used to lock up every other week in a different
hardware environment. I haven't seen this kind of trouble with the
Tekram DC-390U I used to use, but I was too lazy to replace the Tekram
until now.

-- 
Matthias Andree

Encrypted mail welcome: my GnuPG key ID is 0x052E7D95 (PGP/MIME preferred)