Also look at performance data and see whether it makes sense what you want to do. I have seen installations that were spreading the load over a dozen front-end servers all running on the same z/VM image, with a lot of the requests just queue for the back-end database. You can burn a lot of resources just to determine which server should handle the request, and may achieve little when they share the resources.
In an architecture from the discrete world, it is not always obvious which risks are mitigated by what part of the solution. When you transpose that to a Linux on z/VM implementation, some of the infrastructure failures do not apply or may not be covered by the solution (eg "hardware fail" is not fixed by using another Linux guest on the same z/VM LPAR). Using multiple members on different machines in an SSI cluster covers differnet issues. Duplicating servers that hold no application data is fairly simple, but things get hairy when you duplicate databases. Business may well justify a HA setup, but remember this is not commodity hardware where servers fail for trivial reasons. One of the reasons for using z Systems is that you sometimes can avoid some of the complexity that comes with redundancy on higher levels in the design. When possible, I want to drive the virtual machines at their most efficient load. When a single server could do, it's not more efficient to spread it over a dozen sharing the same resources. Do some measurements to find the healthy load for your application, and monitor usage for those values and add resources when needed. Rob van der Heij http://www.velocitysoftware.com/ On 13 March 2015 at 08:52, Berthold Gunreben <[email protected]> wrote: > Hi, > > Starting with SLES12, there is haproxy included in the HA part of SLES. > > http://www.haproxy.org/ > > Berthold > > On Thu, 12 Mar 2015 19:10:07 +0000 > "Stewart, Lee" <[email protected]> wrote: > > > Does anyone know of an IP “sprayer” for Linux on Z? (To send > > arriving requests on to one of several servers, round robin or load > > balanced.) > > > > Since this isn’t a WAS implementation, the DM with WAS isn’t a > > choice…. > > > > Thanks, > > Lee > > > > Lee Stewart ● VM System Support ● Visa ● Phone: 6(750)4601 - > > +1-303-389-4601 ● [email protected] > > > > > > ---------------------------------------------------------------------- > > For LINUX-390 subscribe / signoff / archive access instructions, > > send email to [email protected] with the message: INFO LINUX-390 > > or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 > > ---------------------------------------------------------------------- > > For more information on Linux on System z, visit > > http://wiki.linuxvm.org/ > > > > -- > ---------------------------------------------------------------------- > Berthold Gunreben Build Service Team > http://www.suse.de/ Maxfeldstr. 5 > SUSE LINUX GmbH D-90409 Nuernberg, Germany > GF: Felix Imendörffer, Jane Smithard, Jennifer Guild, Dilip Upmanyu, > Graham Norton HRB 21284 (AG Nürnberg) > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
