Disks eligible to be assigned to a diskgroup must have the status "CANDIDATE" or "FORMER" or "PROVISIONED".
· CANDIDATE - Disk is not part of a disk group and may be added to a disk group with the ALTER DISKGROUP statement
· PROVISIONED - Disk is not part of a disk group and may be added to a disk group with the ALTER DISKGROUP statement. The PROVISIONED header status is different from the
CANDIDATE header status in that PROVISIONED implies that an additional platform-specific action has been taken by an administrator to make the disk available for ASM.
· FORMER - Disk was once part of a disk group but has been dropped cleanly from the group. It may be added to a new disk group with the ALTER DISKGROUP statement.
You don't need change anything on OS Level. Oracle will reuse asmdisk dropped without needs perform any administrative task on OS Level.
While creating a new diskgroup, can I name a disk in "former" state to this new diskgroup ??
No my question is , when i use the command create diskgroup, can I add this disk with former status ?
I understood your question and already answered: Yes.
(Disks eligible to be assigned to a diskgroup must have the status "CANDIDATE" or "FORMER" or "PROVISIONED")
Does not matter if is command ALTER or CREATE diskgroup the DISK is eligible with one of this state above.
PS: FORMER state is just a warning that you removed that disk from a diskgroup and if you reuse it will be impossible to recover any data on that disk.
Despite that there is no option to add the disk back in diskgroup and recover that data ... maybe Oracle Support may be able to recover them, because when disk is removed only header of DISK is changed, Oracle does not format the disk.