Linux memory optimisation in 64bit IBM processor

[Former Member]

Hi All,

Its my first thread in my SDN.

We are about to migrate a new system in our environment

The new hardware will be IBM x3500 64bit with 20GB and for some unavoidable reasons we are planning to the use this system as 32 bit OS

I am aware if we use the system as 32 bit we have to compromise the memory and performance. But I like to know will this cause a performance problem in SAP or we will not be able to avail the complete usage of memory in the applications and also in case of hardware issue will IBM support us?

Kindly give your thoughts and with your inputs i can take it up further.

Regards

[lbreddemann · Accepted solution]

>

> Hi All,

>

> Its my first thread in my SDN.

>

> We are about to migrate a new system in our environment

>

> The new hardware will be IBM x3500 64bit with 20GB and for some unavoidable reasons we are planning to the use this system as 32 bit OS

>

> I am aware if we use the system as 32 bit we have to compromise the memory and performance. But I like to know will this cause a performance problem in SAP or we will not be able to avail the complete usage of memory in the applications and also in case of hardware issue will IBM support us?

Hi there,

since 32-Bit support is basically just not there for most current SAP product releases, you won't even get to the point where performance would be your concern.

A new server installation, with current product versions - there's no way to do this right on 32-Bit.

regards,

Lars

[brian_walker · Accepted solution]

From the SAP installation guide:

"As of SAP NetWeaver 7.0 SR3, you must install an SAP system only on 64-bit operating systems.

For the dialog instance, you can still use a 32-bit operating system. Therefore, you only see the folder Software Life-Cycle Options on the Welcome screen when you start the installation from a 32-bit installation master DVD.

You might need to install dialog instances on 32-bit operating systems if you want to use 32-bit SAP NetWeaver components, such as Adobe document services. However, first check whether such 32-bit components can run on 64-bit operating systems. If so, we recommend running these 32-bit components on a 64-bit operating system."

So if you are installing with the Netweaver 7.0 SR3 or higher version of sapinst, you can forget using 32-bit for anything except the dialog instances, and SAP still recommends running even those on a 64-bit OS.

Good luck!

[Former Member · Accepted solution]

for some unavoidable reasons 

If this is because of some 3rd party software only available on 32-bit, then you should check if it isn't running on a 64-bit platform. A lot of the 32-bit stuff still runs on 64-bit. In that case you could still install SAP and the database with the 64-bit software.

Regards, Michael

[Former Member · Accepted solution]

Hi all,

Thanks for your replies,

The reason which I am asking is we are about to migrate our system(Linux SAP 4.7 with oracle 32 bit system). We got a new server with Xeon 64bit processor from IBM. But for some unaviodable reason we are forced to install 32 bit OS and not 64bit in the new hardwarer. So while surfing in thread we understood that if we use 32 bit OS in 64bit processor you need to compromise on memory and in turn you will not be able to use RAM20GB completely.

So I have raised this question in SDN.

Regards

Harini

[markus_doehr2 · Accepted solution]

> The reason which I am asking is we are about to migrate our system(Linux SAP 4.7 with oracle 32 bit system). We got a new server with Xeon 64bit processor from IBM. But for some unaviodable reason we are forced to install 32 bit OS and not 64bit in the new hardwarer.

A 64bit OS can run 32bit applications. The only reason where this does not work is kernel drivers/device drivers. So I'd check with your "unavoidable vendor" if you can run that 32bit app on a 64bit OS.

> So while surfing in thread we understood that if we use 32 bit OS in 64bit processor you need to compromise on memory and in turn you will not be able to use RAM20GB completely.

True. And you will, depending on the load of the system, having a hard time to keep it up and stable and fast.

Markus