Are wipefs -af and mdadm --zero-superblock equivalent for erasing raid metadata?
By Emma Terry •
I saw instructions about how to remove software raid, and some of them contain both instructions: wipefs -af <device> and mdadm --zero-superblock --force <device>.
Is it neccesary to use both? How do they differ in result?
Here I have raid made of /dev/sda3 and /dev/sdb3. I have made a small test, and it looks like result is the same.
machine1:~# wipefs /dev/sda3 # <-- see the signature on sda3
offset type
----------------------------------------------------------------
0x1000 linux_raid_member [raid] LABEL: machine1:md_system UUID: 54f255a8-c32d-2a67-f728-151f89a7471b
machine1:~# wipefs -af /dev/sda3 # <-- wipe signature using wipefs
/dev/sda3: 4 bytes were erased at offset 0x00001000 (linux_raid_member): fc 4e 2b a9
machine1:~# wipefs /dev/sda3 # <-- as you can see, signature was erased
machine1:~#
machine1:~# wipefs /dev/sdb3 # <-- see signature on sdb3
offset type
----------------------------------------------------------------
0x1000 linux_raid_member [raid] LABEL: machine1:md_system UUID: 54f255a8-c32d-2a67-f728-151f89a7471b
machine1:~# mdadm --misc --zero-superblock --force /dev/sdb3 # <-- wipe signature using mdadm
machine1:~# wipefs /dev/sdb3 # <-- as you can see, signature was also erased
machine1:~# 1 Answer
Both instructions lead to zero-ing the superblock, that means deleting the signature of the filesystem which is here the metadata about the RAID.
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