[Zope] Re: Fail-safe redundancy policies for Zope

[Ausum Studio]

Thanks Paul, for your precise answer. It contains exactly the sort of
caveats I was looking for.


Ausum



----- Original Message ----- 
From: "Paul Winkler" <pw_lists at slinkp.com>
To: <zope at zope.org>
Sent: Thursday, October 07, 2004 10:39 AM
Subject: Re: [Zope] Re: Fail-safe redundancy policies for Zope


> On Thu, Oct 07, 2004 at 08:16:33AM -0500, Ausum Studio wrote:
> > Paul, Tres, thanks for your responses.
> >
> > Has anyone in the community tried any other non-standard way to
accomplish a
> > live backup, like to rely on a synchronization proccess auto-triggered
by
> > parallel installations?. I'd like to go this way as the first thing to
try ,
> > so now I'm looking for caveats from people who have alredy tried the
Zsyncer
> > way or the likes.  :)
>
> Well, ZSyncer is an application-layer replication tool rather than
> a database-layer replication tool. That is, it takes live objects
> from one Zope and pushes them to another. This means that your two
databases
> are not really identical, they contain the same object data only for the
> most recent revisions of the particular objects that you sync.
>
> Some limitations:
>
> *) It's slow for large data
> *) It eats a lot of RAM for large objects
> *) It's push-only - you cannot pull from the remote host to the local
host.
> *) It doesn't preserve history
> *) it fails if you don't have exactly the same Products installed on
> both systems  .
> *) it uses HTTP and basic auth, so it's up to you to ensure security
> by using SSL or a VPN tunnel or whatever.
> *) it frequently mis-reports whether objects are in sync or not
> (it uses bobobase_modification_time, an inherently flawed approach).
>
> But, it is often useful, and in fact I'm working on rolling out another
> release with a lot of fixes/improvements (and probably new bugs
> so there'll be a release candidate or two).
>
> -- 
>
> Paul Winkler
> http://www.slinkp.com
> _______________________________________________
> Zope maillist  -  Zope at zope.org
> http://mail.zope.org/mailman/listinfo/zope
> **   No cross posts or HTML encoding!  **
> (Related lists -
>  http://mail.zope.org/mailman/listinfo/zope-announce
>  http://mail.zope.org/mailman/listinfo/zope-dev )
>