ASM实例未启动就可以创建ASM DISKGROUP吗？

jayli426

Yong Huang 发表于 2015-5-21 23:11
> 创建 第一个diskgroup的时候，ASM实例到底是启动还是没有启动啊？

It should already be up. Otherwis ...

今天我才搞清楚这个问题
如果要创建ASM DISKGROUP，那么必须启动ASM实例
但是最初的ASM实例是如何启动的？ 此时启动参数当然不能再ASM DISKGROUP上面
只能是在安装ASM软件的本地目录中

例如
http://docs.oracle.com/cd/E11882 ... sminst.htm#OSTMG136
提到的
When an Oracle ASM instance searches for an initialization parameter file, the search order is:
1.
The location of the initialization parameter file specified in the Grid Plug and Play (GPnP) profile

2.
If the location has not been set in the GPnP profile, then the search order changes to:
a.
SPFILE in the Oracle ASM instance home

For example, the SPFILE for Oracle ASM has the following default path in the Oracle Grid Infrastructure home in a Linux environment:

$ORACLE_HOME/dbs/spfile+ASM.ora

b.
PFILE in the Oracle ASM instance home


这样才是符合逻辑的，只有ASM实例在基于本地目录的spfile或者pfile起来之后，然后再创建ASM_DISKGROUP
然后在将spfile创建到ASM_DISKGROUP，再利用ASM实例能够读取ASM_DISKGROUP中disk_header的能力
就能读取spfile，启动ASM实例了

yingyifeng306

从11.2开始Oracle 集群e标示voting disk files的方法较之前的版本11.1或10.2有所区别，之前的位置存放在OCR中， 不过从11.2开始ocr和votedisk可以作为一个磁盘组存放在ASM了 ， 所以从11gR2开始voting disk file通过GPNP profile中的CSS voting file discovery string来定位。
CSS voting disk file的discovery string将指向ASM，所以它要使用ASM discovery string的值，你可以通过grid用户gpnptool get来查看
ASM实例在启动时只需要通过GPNP PROFILE中的 DiscoveryString找到合适的设备路径，并读取其ASM disk header即可以找到kfdhdb.spfile这个位置属性，从而在没有MOUNT DISKGROUP的情况下读取ASM SPFILE，并成功启动ASM，如果不清楚，可以私聊

yingyifeng306

http://blog.itpub.net/23732248/viewspace-1670854/

Yong Huang

jayli426: Your message #11 is good. But I don't think the initial spfile is named $ORACLE_HOME/dbs/spfile+ASM.ora. I just checked some of my Oracle servers using ASM. Under GI $ORACLE_HOME/dbs, I see

ab_+ASM.dat
hc_+ASM.dat
init.ora
orapw+ASM

I think it's init.ora that was initially used to create the ASM instance, unless there was a file named spfile+ASM.ora and was later renamed to this, but I doubt it. I can check that next time I have another installation.

yingyifeng306: Your messages are appreciated and are very good. But the question here is about *initial* ASM instance during installation, not regular ASM startup after the install. I kind of mixed the two scenarios together too, until today I finally realized why jayli426 continued to be confused.