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Redhat5 HPDM Multipath EVA4400 raw device Problem

Herbert Herzog
Occasional Advisor

Redhat5 HPDM Multipath EVA4400 raw device Problem

Hello,

I had an working Oracle Rac 10g configuration on an EVA5000 without multipath, because teh storage does not support this in our firmware version. I had to migrate to the new storage EVA4400 which supports multipath. The Oracle RAC did work on the EVA4400 without a multipath configuration. After the multipath configuration one node gets troubles with the access to raw devices. The change of the permissions did not work, I use a /etc/rc.local script where die raw devices will be created and the permissions and the owner will be changed. The first symtom was:

+ a chown and chmod immediatly after the raw command fails with: cannot access directory or file
+ if a sleep with 1 second is between the raw and the chown and chmod command then the command is successful.

In both cases the Oracle RAC does not go online because there is no access to the raw devices.
The raw devices are visible with „ls“ and have the right permissions and ownership. A read only access with „dd“ to the raw device reports that the device is busy. But which process access the raw devices?

One workaround to get the Oracle RAC cluster ready services online is to blacklist the devices for OCR and VOTING and use UDEV for that devices to create the raw devices. But I cann’t use the multipath failover feature for this very important devices.

Have anybody an idea?

We use die Oracle Enterprise Linux 5 Update 1 (which is equal to Redhat Advances Server 5 Update 1), Oracle Standard Edition 10g (10.2.0.4), HP Device Mapper Multipath 4.0.0.

Kindly regards.
Herbert Herzog

4 REPLIES
Steven E. Protter
Exalted Contributor

Re: Redhat5 HPDM Multipath EVA4400 raw device Problem

Shalom Herbert,

Few things:
1) Update 2 is due from RH on RH 5 this month. That may help with multipath.
2) Why don't you schedule a firmware update of the EVA so it supports multipath.

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Steven E Protter
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Herbert Herzog
Occasional Advisor

Re: Redhat5 HPDM Multipath EVA4400 raw device Problem

Hello Steven,

thank you for your reply.

Ad 1) do you know in which context there are improvements with multipath? I use a device mapper multipath driver from HP? I don't know how the Update 2 from RH influences this driver.

Ad 2) The firmware from the new storage EVA4400 supports multipath. May I have not described that exactly. The multipath configuration shows the devices in a correct way but the use of raw devices make troubles. One fact is that raw devices are deprecated on RH5 and the way to create raw devices is possible with scripts.

Kindly regards.
Herbert Herzog
chuckrj
Occasional Visitor

Re: Redhat5 HPDM Multipath EVA4400 raw device Problem

So curious how this was resolved - i have same issue working fine on node 2 but node 1 keeps getting busy. We've bounced troubled server, rebuilt powerpath, recreated raw and no luck. Do you recall how you resolved?
Herbert Herzog
Occasional Advisor

Re: Redhat5 HPDM Multipath EVA4400 raw device Problem

Hi,

on Oracle Support the Note 465001.1 Configuring raw devices for Oracle10g R2 (10.2.0) Clusterware on Red Hat/Enterprise Linux 5 (RH/EL5)
describes the solution. That works on my systems.

Best regards,
Herbert