Paul Winkler wrote:
On Wed, Oct 06, 2004 at 02:35:50PM -0500, Ausum Studio wrote:
What are the best, or most used fail-safe redundancy practices suitable to Zope? More in detail, I'm working on a Zope-based system that will store the data inside the ZODB, and one of the design requests is that given an unrecoverable hardware crash, the system could continue running using a mirror installation with the latest backup (not later than half an hour or even less.)
APE looks like the way to go since it allows the use of standard backup software, but you may have tried other possible solutions for a problem like this. According to your experience how would you accomplish it?
I haven't actually implemented either of these, but:
You could spend some $$ and get ZRS from zope corp which IIRC might let you do automatic failover without loss of service. Not sure though.
For full QoS, ZRS out of the box would only support "warm" failover (it would require downing the secondary and bringing it back up as a primary). We have experimented with using 'heartbeat' to automate that, but haven't deployed it in production. If having the appservers degrade to read-only mode on primary failure is a sufficient QoS, ZRS does that automatically.
You could also use DirectoryStorage and frequently replicate to a backup storage server. The backup can't actually serve to ZEO clients as long as you're replicating to it, but you might be able to come up with some scripts that automatically start a live storage process on the backup if the primary fails. Reverting to the primary server might have to be a largely manual process.
Right. 'heartbeat' might help there, too. Tres. -- =============================================================== Tres Seaver tseaver@zope.com Zope Corporation "Zope Dealers" http://www.zope.com