[openbeosstorage] Re: Logging/RAID

"Ingo Weinhold" <bonefish@xxxxxxxxxxxxxxx> wrote:
> > No, I meant:
> > meta data = file and dir inodes, etc
> > user data = actual file data
> > 
> > IIRC, only the former is journalled by BFS.
> Oh, is that true?! Didn't know that.

It's exactly like that: logging file data would be ways to expensive. 
Also, it wouldn't be doable with the current BFS log architecture (it 
only has a maximum of 2048 blocks in the cache).
Losing file data with BFS (and almost any other journaled file system, 
btw) is certainly possible. A journaled file system shouldn't save you 
backups but the time it needs to recover from system failures. It's not 
even safe against hardware failures :-)

> ...
> A central place where all the existing jobs are entered is needed in 
> any case. Whether it should also be the common place for logging, 
> well, 
> I don't know -- I don't think, I understand the whole thing good 
> enough 
> to make some qualified statement at this time. :-)

My plan is like this (for R2, anyway): I will first implement the 
easiest way to get this thing going, and that'll be the spare partition 
approach.
Later, I will investigate in other, more appealing solutions (to Joe 
user including Tyler and me ;-)).
I think we have found enough solution and hints for the problems the 
will come up, that it's time to start developing it. Unfortunately, 
we'll have to wait a bit until it happens, but that's not sooo bad, 
since we get a whole working OpenBeOS during that time :-))

Adios...
   Axel.

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