Info about I/O Scheduling and Disk

[Former Member]

Hello,

We are currently rolling out SRM 5.0 on Linux RHEL 4 with Oracle 10g as the database.

I was just wondering if anyone has changed the I/O Scheduling to use the Oracle recommended "Deadline" algorithm versus the default "CFQ" Completely Fair Queuing method.

I've had a look around and could not find anything from SAP that says that the Deadline algorithm could be used.

Similarly is anyone using Veritas Volume Manager on RHEL 4 and if so is this ok by SAP for Linux. We use it on our Solaris Servers but am not sure if we can use it on Linux.

Regards,

Chengappa Ballachanda

[Former Member]

Thanks for the Info.

I'll do more research into the Volume Manager and follow up with SAP.

I might just change the Oracle parameter and do some testing.

[hannes_kuehnemund]

Dear Chengappa,

Yes, the SAP LinuxLab conducted tests on Linux IO scheduler performance. Please take a look at the following document at SDN:

<a href="https://www.sdn.sap.comhttp://www.sdn.sap.comhttp://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/b02e7988-4e9d-2910-2994-d8b2cf021f12">How Linux schedulers and other I/O related setups influence the ...</a>

Your question regarding Veritas Volume Manager on RHEL 4 is hard to answer. At the moment it is not allowed to use binary only kernel modules with Linux, according to SAP Note <a href="https://websmp230.sap-ag.de/sap(bD1lbiZjPTAwMQ==)/bc/bsp/spn/sapnotes/index2.htm?numm=784391">784391</a>. The SAP LinuxLab advises to open a customer call on the SAP Service Marketplace (component BC-OP-LNX) if you have further questions regarding such drivers or an individual release of such a configuration.

Thanks,

Hannes Kuehnemund

SAP LinuxLab

[markus_doehr2]

> I was just wondering if anyone has changed the I/O

> Scheduling to use the Oracle recommended "Deadline"

> algorithm versus the default "CFQ" Completely Fair

> Queuing method.

> I've had a look around and could not find anything

> from SAP that says that the Deadline algorithm could

> be used.

Anything, that can be configure via echo /proc/<something> can be used. I suggest trying that on a testsystem first. Would be interesting to hear the results

> Similarly is anyone using Veritas Volume Manager on

> RHEL 4 and if so is this ok by SAP for Linux. We use

> it on our Solaris Servers but am not sure if we can

> use it on Linux.

Veritas Volume Manager uses binary-only kernel drivers and is thus not supported by SAP. See Note 784391 - SAP support terms and 3rd-party Linux kernel drivers

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Markus