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Multipath timeout issues with extended 11.2.0.2 – cluster setup. Part II

The second and final post about an issue with a RAC-configuration with two SAN’s. Problem was a i/o-freeze of minutes when crashing one of the two SAN’s. The first post I ended with a ‘cliffhanger’ because we had a solution, but not tested it yet. Now we tested it.

Start with a mockup of the first post.

Setup:

3 HP DL380 G6 systems with a basic RHEL 5u5 x86_64 installation (2 x RAC clusternodes, 1 x NFS-voting-node)

2 SAN’s HP EVA 6400 systems with 2 controllers each (resulting in 8 paths per device)

Oracle 11.2.0.2

Test: power off 1 SAN. Default result / problem: i/o freeze of minutes, Oracle didn’t like it, started to evict, shutdown, startup = expected behaviour after such a long i/o freeze. But this is not the intention when installing a RAC with two SAN’s….

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By admin|January 3rd, 2012|Database, RAC|0 Comments

Param ‘_datafile_write_errors_crash_instance’ , TRUE or FALSE?

Since 11.2.0.2 there’s a new parameter, “_datafile_write_errors_crash_instance” to prevent the intance to crash when a write error on a datafile occurs . But.. should I use this or not. The official text of this parameter:

This fix introduces a notable change in behaviour in that
from 11.2.0.2 onwards an I/O write error to a datafile will
now crash the instance.

Before this fix I/O errors to datafiles not in the system tablespace
offline the respective datafiles when the database is in archivelog mode.
This behavior is not always desirable. Some customers would prefer
that the instance crash due to a datafile write error.

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By admin|August 26th, 2011|Database, RAC|0 Comments

Multipath timeout issues with extended 11.2.0.2 – cluster setup

We were setting up a 2 node Oracle Grid Infrastructure (RAC) – extended – cluster on top of RHEL 5.5 according to the Oracle standard documentation, with of course a third NFS-node as voting node. Also using ASM to create “host-based”mirror blockdevices for the Oracle software.

The setup is as follows:

3 HP DL380 G6 systems with a basic RHEL 5u5 x86_64 installation (2 x RAC clusternodes, 1 x NFS-voting-node)

2 SAN’s HP EVA 6400 systems with 2 controllers each (resulting in 8 paths per device)

Oracle 11.2.0.2

We did choose this configuration in stead of a configuration with Dataguard because of our high demand of failover-time in case of a node- / SAN- disaster. Should be within 30 seconds. This post raises the question if we made the right decision….

The following analyses and testing by the way has been the effort of my collegae Chris Verhoef, a former RedHat-consultant:

With this setup we are facing the issue that if we loose a complete SAN, the IO’s to the ASM diskgroups will be blocked for approx 3 till 4 minutes. Oracle does not like this. After 70 seconds after a freeze, rdbms is starting to reboot (expected behaviour). To shorten this time we have done some testing with the following parameters:

checker timeout

no_path_retry

dev_loss_tmo

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By admin|August 25th, 2011|Database, RAC|0 Comments

Restoring OCR on 11.2.0.2-cluster

As the documentation about restoring an OCR did not work as it should be, the following has been succesfully tested…

Log on as “root”
# . oraenv +ASM1
# ./ocrconfig -showbackup
# ./ocrconfig -showbackup manual

Stop the cluster on all nodes

# crsctl stop crs

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By admin|May 15th, 2011|Database, RAC|0 Comments

My RAC project with Openfiler, part II – grid infrastructure and database

This is the second post of my little project of building my own RAC on my Windows7-desktop (64-bits, 8GB RAM), using 3 VM’s (VM-workstation , 7.1.3 build-324285) :

2 VM’s for two RAC-nodes, based on OEL 5.5, 11.2.0.2 for infra, and database.
1 VM as my own SAN, based on Openfiler 2.3 (free), for ASM.

My goal: just a little bit hands-on experience with Openfiler, and do some testing with RAC 11gr2, and especially 11.2.0.2. Maybe it’s helpful for somebody else, so I’ll post my experiences. Steps I’m gonna perform.

- The first post handled the following:

1. Planning my installation

2. Create a VM with OpenFiler

3. Configure Openfiler

- The second post (this post):

4. Create a VM as node rac1 and configure ASM

5. Create a VM as node rac2

6. Install Oracle RAC Infrastructure

7. Install Oracle RAC software

8. Install Oracle RAC database

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By admin|January 24th, 2011|Database, RAC|6 Comments