[Users] Memcached...

[David Merrill]

Hi All,

I’ve been struggling with a POC where I’ve got two Zimbra servers (both with proxy, LDAP, mailbox, SMTP sevices installed) in two different data-centers paired up as a “farm” (with the hope that I’ll be able to ultimately migrate mailboxes between them). I’ve arranged DNS-resolution, ACLs and local UFW firewall rules so each server can find & fully-access the other (via the others public-IP address). Pairing up the servers was straightforward enough (LDAP MMR is up and running) and I can fully manage both servers from either proxy server.


  *   End-user mailbox access via the web-UI has issues though. I THINK I’ve isolated it to memcached (it’s running on both Zimbra servers – at some point I’ll retire one of the servers after mailboxes are migrated).
  *   What happens is web-UI partially loads (looks mostly fine, but the folder on the left hand side is missing and  some of the tabs are broken (they throw javascript errors – due to missing content).
  *   Looking through the logs it seems that each server is having trouble getting to port 11211 (memcached) on the “other server”
  *   Despite that I could telnet to the other server on port 11211 just fine.

I’ve got a support ticket open w/Zimbra but I wanted to ask the group a couple questions based on my observations.

Support had me set the following on each server:

zmprov ms $(zmhostname) zimbraMemcachedBindAddress 127.0.0.1
zmprov ms $(zmhostname) zimbraMemcachedClientServerList 127.0.0.1

Once that was one the web-UI was “fine” (albeit a bit slower – because I think memcached on each server has been isolated to itself).

Collateral-damage on this was that ActiveSync clients starting having issues (lots of log entries in nginx.log complaining about not being able to get to memcahed).r

Questions (I’ve read much about memcached but references to this are slim):


  *   What is zimbraMemcachedClientServerList for exactly? (I THOGUHT it might be a layer of security – listing allowed clients & set allowed private/public IPs – but no joy there)

Also:


  *   Is memcached (as it’s meant used in Zimbra) cool to be running on multiple servers?
  *   If so are the memcached processes(as it’s meant used in Zimbra)  on each server supposed to talk to each other?

Thanks for your consideration,
David


David Merrill
Senior Systems Engineer,
Managed and Private/Hybrid Cloud Services
OTELCO
92 Oak Street, Portland ME 04101
office 207.772.5678<callto:207.772.5678>
http://www.otelco.com/cloud-and-managed-services

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