Oracle Kfed Disk header copy

Disk header copy

Lately there is an extra copy of the asm disk header. This copy can be used to fix the real header using kfed with the

repair option.

Location

This copy is stored as the last block of the PST. That means it is in the last block of allocation unit 1 (the original is

block 0 of au 0). The default sizes for an allocation unit is 1M and for the meta data block size is 4K, meaning 256

blocks in each au. So typically the copy is in au 1 block 254. (ASM counts from zero, the original is in allocation unit 0

block 0)

kfed repair

Provided you established that the only problem is with the lost/corrupt disk header, the fix is as simple as:

$ kfed repair <disk name>

If the AU size is non-standard, the above will fail with something like:

KFED-00320: Invalid block num1 = [3], num2 = [1], error = [type_kfbh]

But that is expected and no harm is done. All you need to do is specify the correct AU size. E.g. for 4MB AU the

command would be:

$ kfed repair <disk name> ausz=4194304

DUL

DUL will check/use the header copy (always? or only if the main header is bad?) Warn to use kfed if the header is

bad but the copy is good?

References

Bug 5061821 OS UTILITIES CAN DESTROY ASM DISK HEADER fixed 11.2.0.1, 11.1.0.7, 10.2.0.5 and higher.

Note 417687.1 Creating a New ASM Disk Header After Existing One Is Corrupted