Re: ACID-compliant filesystem (was:Re: [CentOS] Re: centos] 4.4 upgrade problems)

[Les Mikesell <lesmikesell@xxxxxxxxx>]

On Sat, 2006-09-09 at 12:43, Lamar Owen wrote:
> On Tuesday 05 September 2006 22:35, R P Herrold wrote:
> > This bug hinges, very much, on the non-atomic nature of 'hot'
> > system updates, and the fact that the yum-needed,
> > sqlite-maintinaed cache of pacakges got munged half way
> > through, to reproduce.
> 
> Sounds like a database type issue; that is, it could be demonstrated that a 
> multiversion concurrency control (MVCC) mechanism, similar to the PostgreSQL 
> backend, for the whole filesystem, would help this sort of thing.  That is, a 
> filesystem on ACID.  (Atomicity, Consistency, Isolation, Durability: the 
> magic mantra of database management).
> 
> A real transactional filesystem would allow truly atomic system updates.  But, 
> of course, there are definite downsides to that.

I think you are missing the big picture here.  Yum is managing the
whole system.  Given an ACID database, would you expect to be
able to upgrade it to a new, potentially incompatible version of
an ACID database with transactions in progress?  What yum needs
is just some special consideration when modifying its own
components.

-- 
  Les Mikesell
   lesmikesell@xxxxxxxxx


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