1、rac心跳的作用：
檢測(cè)集群節(jié)點(diǎn)間的網(wǎng)絡(luò)健康狀態(tài)，還可用做緩存同步刷新及全局資源維護(hù)。在grid control出現(xiàn)后還傳輸數(shù)據(jù)塊，其內(nèi)聯(lián)數(shù)據(jù)通信量比較大，通常是千兆網(wǎng)，當(dāng)然使用萬兆更好。
2、rac心跳能否用直連網(wǎng)線？
直連網(wǎng)線限制RAC至兩節(jié)點(diǎn)，另外直連網(wǎng)線不穩(wěn)定，由此造成的BUG和技術(shù)問題，ORACLE不提供相應(yīng)的技術(shù)支持。
具體看ORACLE官方解釋：
RAC: Frequently Asked Questions [ID 220970.1]中描述
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 for a 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、rac心跳的高可用
rac心跳實(shí)現(xiàn)高可用，可使用雙網(wǎng)口綁定的技術(shù),操作系統(tǒng)層面實(shí)現(xiàn)。雙網(wǎng)口綁定常見有負(fù)載均衡和主備模式。負(fù)載均衡可提供兩倍的帶寬(實(shí)際并達(dá)不到，只是可快一些)，但從可靠性角度來說，建議主備模式。在主備模式下,當(dāng)一個(gè)網(wǎng)絡(luò)接口失效時(shí)(例如主交換機(jī)掉電等),不會(huì)出現(xiàn)網(wǎng)絡(luò)中斷,系統(tǒng)會(huì)按照/etc/rc.d/rc.local里指定的網(wǎng)卡順序工作,機(jī)器仍能對(duì)外服務(wù),起到了失效保護(hù)的功能。
補(bǔ)充資料：
linux系統(tǒng)下bond mode參數(shù)說明：（mode=4 在交換機(jī)支持LACP時(shí)推薦使用，其能提供更好的性能和穩(wěn)定性）
0－輪詢模式，所綁定的網(wǎng)卡會(huì)針對(duì)訪問以輪詢算法進(jìn)行平分。4、rac雙心跳的可行性
rac心跳使用雙網(wǎng)口綁定后，是一個(gè)私有的地址隸屬于一個(gè)vlan，采用主備模式，兩條網(wǎng)線分別連接兩個(gè)不同的交換機(jī)。這是操作系統(tǒng)層面就可實(shí)現(xiàn)的。如果rac心跳采用兩個(gè)私有VLAN，那么心跳就會(huì)有兩個(gè)私有地址。雙心跳地址間如何做負(fù)載均衡或主備模式，就由ORACLE數(shù)據(jù)庫自己來實(shí)現(xiàn)（操作系統(tǒng)層不再做綁定）。oracle在11G R2之后的版本11.2.0.2里支持這種方式,由于這個(gè)HAIP新特性剛推出有BUG，建議大家使用11.2.0.4版更穩(wěn)定。官方的舉例是針對(duì)多個(gè)數(shù)據(jù)庫instance高互連帶寬要求的。
官方具體說明請(qǐng)參見http://docs.oracle.com/database/121/RACAD/admin.htm#RACAD7295
文檔ID 1210883.1詳細(xì)介紹了HAIP，其中對(duì)HAIP的描述如下：
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.*.* 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、每一套業(yè)務(wù)系統(tǒng)數(shù)據(jù)庫的RAC心跳是否需要做vlan隔離？
oracle官方?jīng)]有明確說明，出于安全的特定要求，自己可以做VLAN隔離，小的VLAN比較多則會(huì)增加一些管理和配置成本。
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