Sunday, June 24, 2018

ASM disk error synchronous I/O operation to a disk failed oracle RAC on AIX.

Oracle RAC cluster on AIX 6.1 TL08 : Error while restoring RMAN backup on ASM disk.
ORA-15080: synchronous I/O operation to a disk failed

While restoring oracle RMAN backup, we faced error "synchronous I/O operation to a disk failed".

After checking at database end they confirmed that backup is ok and everything is fine from their end,but we thought that why should we take oracle RMAN backup one more time and try with new fresh backup.
we took backup once again and tried to restore on ASM oracle RAC setup.but no success :(.
So its OS team turn now,after doing analysis on OS end.found that ASM disk reserve policy is not correctly set and this is the main reason for  error "synchronous I/O operation to a disk failed".
so we changed ASM disk reserver_lock policy by using following command.
on server ASM disk was from EMC storage.

command : 

#chdev –l hdiskpowerX –a reserve_lock=no 

check attributes after change using command.

# lsattr –El hdiskpowerX |grep -i reserve_lock

After doing resreve_lock policy database team tried backup restore on oracle RAC and guess what this time its work perfect!!!!!!!!.
So error was at OS end it’s because of not done proper pre-requisite check.

Pre-requisite for oracle ASM disk
1. All ASM disk reserve_lock must be set to "no"
check attribute using commnad # lsattr –El hdiskpowerX.
2. check and confirm that all ASM disk having correct ownership set.

If ownership is not correctly set then at oracle RAC end they will not able to detect ASM disk

also i like to share how to assign RAW/ASM disk to Oracle RAC cluster ,there are some simple steps.

1.Ask storage guy to assign disk from storage to AIX LPAR.
2.detect that disk on AIX LPAR by executing "cfgmgr" command.
3.After detecting disk don't assign any PVID to DISK and don't create any file system on it.
4.simply change reserve_lock policy to no_reserve and change ownership to oracle user .
5.after this inform oracle admin then he will detect disk and assign to ASM group.

RAW/ASM disk not contain any file system.its purpose is for getting performance.

Thanks !!!

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