Cluster LINUX SLES 11

[Former Member]

Hi All,

we are implementing a new ECC 6.0 ENHP4 on SLES11/Oracle11.2. We have all the non-Production systems on VMware. We have read (oss note 1173954) that Oracle has not certified any of its products on VMware virtualized

environments. For this reason we want to use for the production system a physical cluster with two nodes : one for the DB+CI and the other for the application servers. In your opinion which are the problems in case of heterogeneous cluster with one physical node and the other on VMWare?

Thank you very much for your collaboration.

Bob

[Former Member]

Hello Bob,

SAP note 1173954 is formulated deliberately ambigous:

Oracle has not certified any of its products on VMware virtualized environments. Oracle Support will assist customers running Oracle databases on VMware in the following manner: Oracle will only provide support for issues that either are known to occur on the native OS, or can be demonstrated not to be as a result of running on VMware.

This really means that Oracle does support productive systems on VMware. In case of problems it might happen that you have to reproduce these problems on a non-virtualized environment. So Oracle does not want to chase VMware bugs. I have spoken with people who have experience with Oracle productive systems on VMware, they said they never have encountered any such problem on VMware and deem it highly unlikely they ever will.

Of course Oracle wants to push their product Oracle VM, but I would stick with one consistent approach. So if you have the preprod systems on VMware then I would also put the productive system on VMware.

Regards,

Mark

[Former Member]

Hi Mark,

thank you very much for your reply. Any consideration about the possibility to have a cluster on HP servers (BL620 or BL680) with a node physical and a node virtual?

Regards

Bob

[Former Member]

Hello Bob,

in the good old times we used to have HP ServiceGuard on Linux, so any considerations

of VMware were quite pointless. Now without HP ServiceGuard I wonder which cluster

software you refer to? Is it the SLES HA extension, Veritas Cluster or Oracle RAC?

I have no personal exerience with either of these solutions, but I wonder why

you want to combine virtualization software like VMware with a cluster software?

Never heard of anyone yet with such kind of combination, so I am just wondering.

Regards,

Mark

[Former Member]

Hello,

during the SAP High Availability Workshop last year, we tested SUSE Linux Enterprise Server 11 High Availability Extensions on VMware. See SAP Note 1552925 of possible 3rd party clustering software on Linux which can be used for making SAP high available.

One of the partners that participated in last year's workshop was Computer Concept. They wrote a whitepaper of [running SAP on SLE 11 HAe on VMware.|http://www.cc-dresden.de/news/datum/2011/02/28/hochverfuegbarkeit-fuer-sapR-netweaverR-in-vmware-vsphere-4-umgebungen/]

Technically, it is possible to have one node on physical and one node on virtual. There are just some things to consider:

- Choose a robust fencing method. I recommend using [SBD with three devices.|http://www.linux-ha.org/wiki/SBD_Fencing]

- Is the VM part of a VMware HA cluster? Then you have to set the correct isolation response ("leave powered on") for that VM, otherwise you will have the effect of double fencing.

- If you're not only using NFS for shared data but use block devices, you have to make the block devices available for the physical as well as for the virtual server. Therefore, you have to use RDM (in physical compatibility mode) inside the virtual machine. Additionally, you have to choose an appropriate method to mount these as they will probably be named differently in the physical/virtual environment.

Kind regards,

Matthias