Cyrus HA & LB cluster summary

[Marcelo Maraboli]

Great summary Michael.

I have a few questions on what a "shared filesystem" hardware
CAN be:

- iSCSI storage ? (cheap GigaEthernet SAN)

according to Wikipedia http://en.wikipedia.org/wiki/ISCSI ,
only 1 iSCSI-client can be connected to 1 iSCSI-server (disk)
at a time...so this does not allow for a shared FS ?

- Fibre Channel SAN with NFSv4, GSF support

- NAS with with NFSv4, GSF support

- if GFS is mainly for Linux, any NAS or SAN should work ??

regards,


Michael Menge wrote:

> - Shared filesystem Active/Passive
>   This setup can add HA to a normal Cyrus server by storing the Mails and
>   databases on a shared filesystem and monitoring the server with 
> heartbeat.
>   This setup should work with every shared filesystem and there should 
> be no
>   problems with bdb
> 
> - Shared filesystem Active/Active
>   In this setup all users are on all server. The mailboxes and databases
>   are on a shared filesystem so that changes on one server are visible 
> on all
>   other servers. Cyrus depends on the file-locking of the filesystem. 
> NFSv4,
>   GFS, Lustre, and some other shared filesystem affirm that they have
>   file-locking across cluster nodes.
>   The sockets, lock- and pid-files have to stay on a local
>   filesystem or have to be made unique across cluster nodes.
>   BDB seems to have problems in this setup, because the changes of the lock
>   in the mmaped files are not instantly on all clients/nodes and the use of
>   shared memory. You have to compile Cyrus without bdb-support to get 
> rid of
>   the errors. This setup needs no extra servers, and all use the same
>   configuration. In case of server crash the user use one of the other 
> servers.
>   The server can be replaced with an clone of one of the other servers.
>   The storage should be too on a HA  cluster to make the whole 
> mailsystem ha.
> 
> The Active/Active Shared filesystem setup is discussed controvers.
> This setup is not widely used and therefor not tested that mutch.
> But Dave McMurtrie and Scott Adkins have reported of sucsessfull 
> installations
> 
> 
> The following shared Filesystems seem support the file-locking
> 
> GFS            http://sources.redhat.com/cluster/gfs/
> Lustre         http://www.lustre.org/
> NFSv4          http://www.nfsv4.org/
> Polyserve CFS  http://www.polyserve.com
> Veritas CFS 
> http://www.symantec.com/enterprise/products/overview.jsp?pcid=1020&pvid=209_1 
> 
> 
> 
> 
> 
> -------------------------------------------------------------------------------- 
> 
> M.Menge                                 Tel.: (49) 7071/29-70316
> Universitaet Tuebingen                  Fax.: (49) 7071/29-5912
> Zentrum fuer Datenverarbeitung          mail: 
> michael.menge at zdv.uni-tuebingen.de
> Waechterstrasse 76
> 72074 Tuebingen
> 
> 
> ------------------------------------------------------------------------
> 
> ----
> Cyrus Home Page: http://cyrusimap.web.cmu.edu/
> Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki
> List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html

-- 
Marcelo Maraboli Rosselott
Jefe Area de Redes y Comunicaciones (Network & UNIX Systems Engineer)
Ingeniero Civil Electronico, CISSP       (Electronic Engineer, CISSP)

Direccion Central de Servicios Computacionales (DCSC)
Universidad Tecnica Federico Santa Maria        phone: +56 32 2654071
Chile.                 http://www.usm.cl   http://elqui.dcsc.utfsm.cl