Shulou(Shulou.com)06/01 Report--

1. The function of rac heartbeat:

Detect the network health status between cluster nodes, and can also be used for cache synchronous refresh and global resource maintenance. Data blocks are also transmitted after the emergence of grid control, whose inline data traffic is relatively large, usually gigabit network, of course, it is better to use 10 gigabytes.

2. Can rac heartbeat use a directly connected network cable?

The directly connected network cable is limited to two nodes, in addition, the directly connected network cable is unstable, and ORACLE does not provide corresponding technical support for BUG and technical problems caused by it.

Let's take a look at the ORACLE official explanation:

RAC: described in Frequently Asked Questions [ID 220970.1]

Is crossover cable supported as an interconnect with RAC on any platform?

NO. CROSS OVER CABLES ARE NOT SUPPORTED. The requirement is to use a switch:

Detailed Reasons:

1) cross-cabling limits the expansion of RAC to two nodes

2) cross-cabling is unstable:

A) Some NIC cards do not work properly with it. They are not able to negotiate the DTE/DCE clocking, and will thus not function. These NICS were made cheaper by assuming that the switch was going to have the clock. Unfortunately there is no way to know which NICs do not have that clock.

B) Media sense behaviour on various OS's (most notably Windows) will bring a NIC down when a cable is disconnected. Either of these issues can lead to cluster instability and lead to ORA-29740 errors (node evictions).

Due to the benefits and stability provided by a switch, and their afforability ($200 fora simple 16 port GigE switch), and the expense and time related to dealing with issues when one does not exist, this is the only supported configuration.

From a purely technology point of view Oracle does not care if the customer uses cross over cable or router or switches to deliver a message. However, we know from experience that a lot of adapters misbehave when used in a crossover configuration and cause a lot of problems for RAC. Hence we have stated on certify that we do not support crossover cables to avoid false bugs and finger pointing amongst the various parties: Oracle, Hardware vendors, Os vendors etc...

3. High availability of rac heartbeat

Rac heartbeat is highly available and can be implemented at the operating system level using dual-port binding technology. It is common to bind dual network ports with load balancer and active / standby mode. Load balancer can provide twice the bandwidth (in fact, it can not be achieved, but faster), but from the point of view of reliability, active / standby mode is recommended. In the active / standby mode, when a network interface fails (for example, the main switch is powered off, etc.), there will be no network interruption, the system will work according to the order of the network card specified in / etc/rc.d/rc.local, and the machine can still serve the outside world, thus playing the function of failure protection.

Supplementary information:

Description of bond mode parameters under linux system: (mode=4 is recommended when the switch supports LACP, which can provide better performance and stability)

0-polling mode, the bound Nic will divide the access equally according to the polling algorithm.

1-High availability mode, only one network card is used at run time, and the rest of the network card is used as a backup, which is recommended when the load does not exceed the bandwidth or pressure of a single network card.

2-based on the load balancing mode of HASH algorithm, the network card is diverted according to the TCP protocol layer of xmit_hash_policy, so that the access from different processing sources can be processed on the same network card as far as possible.

3-broadcast mode, all bound network cards will get the same data, generally used for very special network requirements, such as the need to send the same data to two switches that are not connected to each other.

4-802.3ab load balancing mode, which requires the switch to also support 802.3ab mode. Theoretically, when both the server and the switch support this mode, the maximum bandwidth of the network card can be doubled (for example, from 1Gbps to 2Gbps)

5-the adapter outputs the load balancing mode, and the output data is output through all bound network cards, and only one network card is selected when receiving the data. If the network card that is being used to receive data fails, it will be taken over by other network cards, requiring that the network cards and network card drivers used can get speed information through the ethtool command.

6-Adapter input / output load balancing mode, which realizes load balancing while receiving data on the basis of "mode 5". It not only requires the ethtool command to get speed information, but also supports the dynamic modification of the MAC address of the network card.

4. The feasibility of rac double heartbeat.

After the rac heartbeat is bound with two network ports, a private address belongs to a vlan, using the active / standby mode, and the two network cables are connected to two different switches. This can be achieved at the operating system level. If the rac heartbeat uses two private VLAN, then the heartbeat will have two private addresses. How to do load balancing or active / standby mode between two heartbeat addresses is implemented by the ORACLE database itself (the operating system layer is no longer bound). Oracle supports this approach in version 11.2.0.2 after 11G R2. Since this new HAIP feature has just been released with BUG, it is recommended that you use version 11.2.0.4 to be more stable. The official example is aimed at the high interconnection bandwidth requirements of multiple databases instance.

For official details, please refer to http://docs.oracle.com/database/121/RACAD/admin.htm#RACAD7295

The document ID 1210883.1 describes HAIP in detail, and the description of HAIP is as follows:

Redundant Interconnect without any 3rd-party IP failover technology (bond, IPMP or similar) is supported natively by Grid Infrastructure starting from 11.2.0.2. Multiple private network adapters can be defined either during the installation phase or afterward using the oifcfg. Oracle Database, CSS, OCR, CRS, CTSS, and EVM components in 11.2.0.2 employ it automatically.

Grid Infrastructure can activate a maximum of four private network adapters at a time even if more are defined. The ora.cluster_interconnect.haip resource will start one to four link local HAIP on private network adapters for interconnect communication for Oracle RAC, Oracle ASM, and Oracle ACFS etc.

Grid automatically picks free link local addresses from reserved 169.254. Subnet for HAIP. According to RFC-3927, link local subnet 169.254.room.* should not be used for any other purpose. With HAIP, by default, interconnect traffic will be load balanced across all active interconnect interfaces, and corresponding HAIP address will be failed over transparently to other adapters if one fails or becomes non-communicative. .

The number of HAIP addresses is decided by how many private network adapters are active when Grid comes up on the first node in the cluster. If there's only one active private network, Grid will create one; if two, Grid will create two; and if more than two, Grid will create four HAIPs. The number of HAIPs won't change even if more private network adapters are activated later, a restart of clusterware on all nodes is required for the number to change, however, the newly activated adapters can be used for fail over purpose.

5. Does the RAC heartbeat of each business system database need to be isolated by vlan?

Oracle has not made it clear that it can do VLAN isolation because of specific security requirements, while a large number of small VLAN will increase some management and configuration costs.

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