Re: ext4 features

Helge Hafting
2006-07-04T12:56:37Z

On Mon, Jul 03, 2006 at 05:50:22PM -0400, Valdis.Kletnieks@vt.edu wrote:
> On Mon, 03 Jul 2006 17:34:18 EDT, Bill Davidsen said:
> > I think he is talking about another problem. RAID addresses detectable
> > failures at the hardware level. I believe that he wants validation after
> > the data is returned (without error) from the device. While in most
> > cases if what you wrote and what you read don't match it's memory,
> > improving the chances of catching the error is useful, given that
> > non-server often lacks ECC on memory, or people buy cheaper non-parity
> > memory.
>
> There's other issues as well. Why do people run 'tripwire' on boxes that
> have RAID on them?

To notice hacking. RAID protects against hardware failure, it does
_not_ protect against any change that comes through the normal
filesystem channels. RAID doesn't help the slightest against
viruses and hackers. RAID is _not_ a backup, when a hacker
(or a user error) changes an important file, it is changed
in all mirrors of a raid-1 set, and raid-5 checksums are updated
so the change becomes valid. But tripwire will notice that
a protected file changed.

Helge Hafting