ACID-compliant filesystem (was:Re: [CentOS] Re: centos] 4.4 upgrade problems)
Les Mikesell
lesmikesell at gmail.com
Sat Sep 9 18:42:37 UTC 2006
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 at gmail.com
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