Wednesday, June 16, 2010

Maximum on Oracle Cluster

What are the maximum number of nodes under OCFS on Linux ?
Oracle 9iRAC on Linux, using OCFS for datafiles, can scale to a maximum of 32 nodes. According to the OCFS2 User Guide User Guide, OCFS 2 can support up to 255 nodes.

What is the maximum number of nodes I can have in my cluster if I am using OCFS2?
Theroetically you can have up to 255 however it has been tested with up to 16 nodes.

What is the maximum distance between nodes in an extended RAC environment?
The high impact of latency create practical limitations as to where this architecture can be deployed. While there is not fixed distance limitation, the additional latency on round trip on I/O and a one way cache fusion will have an affect on performance as distance increases. For example tests at 100km showed a 3-4 ms impact on I/O and 1 ms impact on cache fusion, thus the farther distance is the greater the impact on performance. This architecture fits best where the 2 datacenters are relatively close (<~25km) and the impact is negligible. Most customers implement under this distance w/ only a handful above and the farthest known example is at 100km. Largest distances than the commonly implemented may want to estimate or measure the performance hit on their application before implementing. Due ensure a proper setup of SAN buffer credits to limit the impact of distance at the I/O layer.

How many nodes can be had in an HP-UX/Solaris/AIX/Windows/Linux cluster?
The number of nodes supported is not limited by Oracle, but more generally by the clustering software/hardware in question.

When using solely Oracle Clusterware: 63 nodes (Oracle 9i or Oracle RAC 10g Release 1) With 10g Release 2, the maximum nodes is 100
When using a third party clusterware:
Sun: 8
HP UX: 16
HP Tru64: 8
* 8 nodes for Physical Shared (CLVM) SSA disk
* 16 nodes for Physical Shared (CLVM) non-SSA disk
* 128 nodes for Virtual Shared Disk (VSD)
* 128 nodes for GPFS
* Subject to storage subsystem limitations
Veritas: 8-16 nodes (check w/ Veritas)
For 3rd party vendor clusterware, please check with the vendor.

How many nodes are supported in a RAC Database?
With 10g Release 2, we support 100 nodes in a cluster using Oracle Clusterware, and 100 instances in a RAC database. Currently DBCA has a bug where it will not go beyond 63 instances. There is also a documentation bug for the max-instances parameter. With 10g Release 1 the Maximum is 63. In 9i it is platform specific due to the different clusterware support by vendors. See the platform specific FAQ for 9i. with 11g Release 1 and 11g Release 2 100

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