Re: ext4 features

[Helge Hafting]

On Mon, Jul 03, 2006 at 05:50:22PM -0400, Valdis.Kletnieks@xxxxxx 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
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