Many Physical Servers

[Former Member]

Hi guys... my question is... i have 2 Physical Servers.... which VMWare product can i use to consolidate this...so for example

Server 1 has 8GB RAM, Server 2 has 4GB RAM...... i need to install 2 SAP Instances (2 VM Instances) with 6GB RAM each...

Regards

Chris

[Former Member]

pooling resources is not possible with vmware

[Former Member]

pooling resources is not possible with vmware

Well, it actually is, but it's a different concept. Pooling resources is more about resource assignments on multiple Virtual Machines across multiple or single ESX hosts. Pooling resources for one Virtual Machine across multiple ESX hosts is not possible.

[markus_doehr2]

> Hi guys... my question is... i have 2 Physical Servers.... which VMWare product can i use to consolidate this...so for example

> Server 1 has 8GB RAM, Server 2 has 4GB RAM...... i need to install 2 SAP Instances (2 VM Instances) with 6GB RAM each...

Technically you can do that this way - but you will have to reconfigure the instances because they are configured to use 8 and 4 GB of RAM. Consolidation is not about equalizing the RAM, why do you want to change the settings? You can likewise install both instances as they are now.

Markus

[Former Member]

the 8 & 4 GB was just an examples... the real situation is that we have many SAP systems & i need to be able to allocate resources & adjust them when required... since we don't have identical hardware i really need to be able to consolidate them before allocating.... i also want to do this @ OS level (VMWare) & not @ SAP level (by having distributed systems).....

[markus_doehr2]

> the 8 & 4 GB was just an examples... the real situation is that we have many SAP systems & i need to be able to allocate resources & adjust them when required... since we don't have identical hardware i really need to be able to consolidate them before allocating.... i also want to do this @ OS level (VMWare) & not @ SAP level (by having distributed systems).....

If you change the amount of memory of a machine you have to reflect that in the application, means, if you e. g. increase the memory on VMWare for a SAP system you have to adapt SAP parameter to make use of that memory. Otherwise the OS will see the memory but will not use it.

And of course you can run a number of SAP systems on the same machine, one with 4 GB, another with 8 GB and another one with 16 GB - if you have enough physical memory.

Markus

[Former Member]

Yes i understand those points... but my question was... i have 2 Physical Servers.... which VMWare product can i use to consolidate this

[markus_doehr2]

If you read the first threads in this forum such as

[SAP Notes regarding VMware virtualization|;

you have all necessary notes that point to VMware.

Basically you have to use ESX or ESXi.

Markus

[Former Member]

i did read the notes.. and they only give recommendations... my question is.... let me try again,,,,

For example.... have 2 physical servers (4GB RAM, 8GB RAM)....can i consolidate these 2 server using ESX or ESXi and install 1 SAP instance (one VM) which will have ...let's say have 10GB of RAM available for it (from the total 8+4=12) ????

[Former Member]

The best answer would have to be "it depends". What are your 2 physical servers now ( 1 central instance & 1 db or 1 central instance/db & 1 application server)? If your 2 servers are the SAP system and the DB instance then the answer could be yes.

If your physical servers are 1 central instance and 1 application server then you will need more info. If this is the case, you need to know why the requirement for the application server.

Thanks,

Jared

[Former Member]

both server do not have anything on it... what i want to do is install ESX or ESXi on both of them... create 1 VM instance using the consolidated hardware (10GB RAM) & install 1 SAP instance on the VM instance (DB & CI in one VM)

[markus_doehr2]

> For example.... have 2 physical servers (4GB RAM, 8GB RAM)....can i consolidate these 2 server using ESX or ESXi and install 1 SAP instance (one VM) which will have ...let's say have 10GB of RAM available for it (from the total 8+4=12) ????

Memory should not be overcommittet (if you read the notes) - so if you have two physical servers with 4 and 8 GB and you want to consolidate them onto one machine and expect to not change the configuration of the machines and expect the same performance then you have to use at least use the same amount of memory plus some more for the hypervisor (VMware) itself. Calculate 10 - 20 % more memory (read the notes).

I'm not sure why you are understanding consolidation as "using less memory than before", can you elaborate?

Markus

[Former Member]

we mostly have both CI & DB on one box.. this is due to lots of training & sandbox systems...and since we have a few old server with NOT so great hardware, we would like to consolidate & use them for sandbox systems (8+4 & use 10 for the SAP sandbox, 2 for the OS ...etc)

[Former Member]

If you are wanting to create 1 VM from the 2 physicals, the most memory you can use is 8gb - 20% overhead. When you put 2 servers into a VM cluster, you don't get the total of all of the memory (12gb in this case). You will get an 8gb ESX(i) host and a 4gb ESX(i) host. If you are wanting on 1 SAP VM, then the most you could do is approx. 6.5gb and in that instance it could only run on the 8gb physical server.

Thanks,

Jared

[Former Member]

Christopher, I don't really get your point, it seems that you want to "pool" RAM of two ESX hosts for one VM. This is not possible. The maximal amount of RAM for a VM is always the RAM the host has installed physically (minus a certain overhead). I'd use SAPs architecture and split the instances, installing the database on the host with 4 GB RAM (a 3 GB VM would be sufficient) and the application server on the host with 8 GB RAM (like Jared said, a 6,5 GB VM). If you use Linux instead of Windows as guest OS, you have more RAM available for your SAP software.

Regarding the overhead, for a small host the calculation of Jared is correct, as you have 400 - 700 MB overhead for a VM with 6,5 GB RAM (depending on how much vCPUs you assign to the VM), the service console uses 272 - 800 MB RAM (can be configured) and the VM Kernel only around 200 MB. But a host with more VMs and more RAM does have less overhead than 20 %. Because of Transparent Page Sharing effects, the overhead of a host with 128 GB RAM could have 2 - 6 GB only, which are ~ 5 %. The best is to consult the Resource Management Guide from case to case regarding overheads.

[Former Member]

yes.. what i wanted to do was pool the old servers we have & use it for SAP Sandbox systems.... but i see that is not possible.

Thanks for the support.

Regards

Chris