(Sorry about the cross post! I did not pay attention to what I was typing in the address, but perhaps this is the best place for this question anyway.)
to achieve what end?
One of my projects has a requirement for providing 99.99% uptime when hosting in their data center. Our Zope / Plone solution will be replacing an ASP / SQL Server solution that has 2x web servers and 2x SQL Servers (using log shipping). Tentatively, my hosting recommendation resembles two web servers, running Apache / FastCGI / Zope, and then two servers running ZEO / ZODB and ExFile. My current thoughts would be to commission SAN space between the two ZEO servers so that the Data.fs, etc. would be shared between the two database servers. SAN space is expensive, though, so when I saw a posting about Zsyncer, I was wondering if there might be a solution for keeping two instances of a ZODB synced up. We already have two Cisco CSS to handle heart beats and failover. Thanks for the responses... -Matt
On Sun, Jul 31, 2005 at 02:34:26PM -0700, Matt Howell wrote:
so when I saw a posting about Zsyncer, I was wondering if there might be a solution for keeping two instances of a ZODB synced up.
It's really only intended for manual sync of smallish amounts of data. I would not rely on it for automated mirroring of an entire ZODB, even if you can cook up some appropriate scripting it is unlikely to be fast enough for that. If you need "warm" or "hot" failover of your ZEO server, or you have such intense performance that you need to load-balance among multiple live ZEO servers, then the only solution I am aware of is Zope Corp's ZRS product, which is commercial and AFAICT is priced according the (probably reasonable) assumption that anyone who really needs it has pretty deep pockets. See zope.com for more info. For free / open-source solutions, AFAICT it may be possible to have automated cold failover, but not multiple live ZEO servers at once. I'm currently investigating the possibility of automated cold failover using DirectoryStorage's replication tool to keep the backup system up to date. (See recent thread "Replication and cold failover" on dirstorage-users mailing list, find archives at dirstorage.sf.net). You could probably do something similar with Filestorage by using repozo to frequently make incremental backups, and rsync to copy them to your backup server. -- Paul Winkler http://www.slinkp.com
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Matt Howell -
Paul Winkler