在AIX系统上使用ASM需要注意磁盘不要有PVID

秋风No.1

使用了PVID，在创建ASM的时候，会清除掉PVID，而当系统重启后，操作系统会重写PVID，这样会导致ASM磁盘失效

如果已经使用了带有PVID的磁盘，可以参考MOS上这篇文档进行处理。

Corrective Action for Diskgroup with Disks Having PVIDs [ID 750016.1]
		修改时间 19-APR-2011     类型 HOWTO     状态 PUBLISHED

In this Document
  Goal
  Solution
  References

Applies to: Oracle Server - Enterprise Edition - Version: 10.1.0.2 to 11.2.0.2 - Release: 10.1 to 11.2
IBM AIX on POWER Systems (64-bit)
IBM AIX Based Systems (64-bit) Goal You have created a diskgroup with disks having PVID and the diskgroup is in use. There is no diskgroup metadata corruption reported yet. You now know that ASM Disk should not have PVID as alerted in MetaLink Note 353761.1

This note will give the steps to clear the PVID of these ASM Disks.
Solution When the PVID is set to a disk in a volume group, the PVID is stored in two locations. In Physical disk header ( within first 4K )and in AIX's system object database, called ODM ( Object Data Manager ).

When the diskgroup is created, the disk header information of PVID is overwritten. However, with reboot the OS, from ODM, AIX might try to restore the PVID information onto the disk header, there by destroying the ASM metadata. So we need to run the following commands to update the ODM:

1] Do not reboot any node.

2.1] Drop one disk at a time from the diskgroup.

2.2] Clear the PVID for the disk

# chdev -l hdisk5 -a pv=clear

Run this on ALL the nodes in case of RAC.

2.3] Check the disk does not have the PVID from ALL the nodes

# lspv

2.4] Add the disk back to the diskgroup

2.5] Do this for all the disks having PVID in the diskgroup, one by one. Take care that the rebalance is
complete from the drop/add disk command before going for the next disk.

OR

3] This needs downtime:

3.1] Take 'dd' backup of the disk headers

# dd if=/dev/hdisk5 of=/tmp/d5.txt bs=1024 count=1024

3.2] Shutdown ASM instance ( on ALL the nodes in RAC setup ).

3.3] Clear the PVID

# chdev -l hdisk5 -a pv=clear

Run this on ALL the nodes in case of RAC.

3.4] Check the disk does not have the PVID from ALL the nodes

# lspv

3.5] Start the ASM Instance(s) and mount the diskgroup on ALL the nodes


WARNING:
This last command overrides the content of the disk header and so could be destructive if not correctly used! If you have any doubt, please contact the Oracle Support before any action.
References NOTE:353761.1 - Assigning a Physical Volume ID (PVID) To An Existing ASM Disk Corrupts the ASM Disk Header