[CentOS] CentOS and mdadm

Tue Dec 1 11:48:24 UTC 2020
Nicolas Kovacs <info at microlinux.fr>

Hi,

I'm regularly using software RAID for my CentOS storage servers, either with
RAID 1 or RAID 6 depending on the number of disks.

Here's two questions about mdadm I've always been wondering about.

1. I'm not sure about the --metadata option. Let's say I want to create a
simple RAID 1 setup, I'm usually doing it like this:

# mdadm --create /dev/md/boot --level=1 --raid-devices=2 \
  --metadata=1.2 /dev/sda1 /dev/sdb1

If anyone can explain the exact meaning of --metadata, I'd be grateful.

Oh, and is it OK to use --metadata=1.2 in CentOS 7.x and 8.x ?

2. I'm regularly encountering the mdadm --misc option in various tutorials on
the Internet. I looked it up in mdadm's manpage, but it doesn't seem to be
documented.

Any idea what this option does ?

Cheers,

Niki

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