I´ve came across a problem lately where I plugged in an external hardrive into my centos box.
The stuff that was on it didn´t matter, I planned to use it as a backup disk for the files I actually care about to be around in case of a catastrophic failure.
So I opened the parted cli replaced the partition table with gpt and created one partition covering the entire drive. All good so far.
Then I wanted to format it to ext4 and it complained that the disk is already in use by the system.
Turns out it was used by something called multipath, Witch I´ve never heard about until this point. Running
multipath -F fixed the issue and I could properly format the partition on the drive and mount it.
I searched online for what multipath would be. And yet I did´t really quite get it.
So my questions are mostly
- What does it do to begin with?
- Why would I want “multiple paths” to access the same damn thing?
- What does multiple paths even mean. I´m thinking like “/mnt/my_amazing_hdd/somefolder” is obviously a paths to my understanding. But maybe the term is used to more than just simple file paths. In witch case I´ve never used this term like that in my life.
- The only thing I could think about was a local path and a samba access url. But that´s not really having multiple paths (I don´t think?). I´d very much imagine samba internally uses the very same paths anyhow. So no multipathing going on what so ever. Just yet another thing that acesses the very same path internally.