In our tracefile of the ASM rebalancer process, every 5 minutes the following line is shown:
NOTE:Unident of disk:/dev/asmspfile
There is not really much information to be found on what this can mean, even on My Oracle Support there is no information found.
I am guessing this message is explained by the fact that the diskname matches our asm_diskstring:
SQL> show parameter asm_diskstring
NAME TYPE VALUE
asm_diskstring string /dev/asm*
but in fact is not part of any (active) diskgroup
In our case this disk, or raw device, contains the shared spfile of the ASM instances across our RAC nodes.
If this assumption is true, then this message can be safely ignored.
What is the risk:
If you don't keep a good administration of what disks have which function, or you mess up with the disk naming convention anyway, the risk exists that you'll add disks to a diskgroup that might be in use for other functions.
Like in our case, if I would not know this disk contains the ASM spfile, it would be very easy to add that disk to a diskgroup. And I doubt if ASM would complain doing so.