2 - Raspberry PI Community Projects

Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
524288 inodes, 2097152 blocks
104857 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2147483648
55 block groups
32768 blocks per group, 32768 fragments per group
8160 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
# mkdir /srv/raid-0
# mount /dev/md0 /srv/raid-0
# df -h /srv/raid-0
Filesystem Size Used Avail Use% Mounted on
/dev/md0 8.0G 249M 7.4G 4% /srv/raid-0
The mdadm --create command requires several parameters: the name of the volume to create
(/dev/md*, with MD standing for Multiple Device), the RAID level, the number of disks (which
is compulsory despite being mostly meaningful only with RAID-1 and above), and the physical
drives to use. Once the device is created, we can use it like we'd use a normal partition, create a
filesystem on it, mount that filesystem, and so on. Note that our creation of a RAID-0 volume on
md0 is nothing but coincidence, and the numbering of the array doesn't need to be correlated
to the chosen amount of redundancy.
Creation of a RAID-1 follows a similar fashion, the differences only being noticeable after the
creation:
# mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sdg2 /dev/sdh
mdadm: largest drive (/dev/sdg2) exceed size (4194240K) by more than 1%
Continue creating array? y
mdadm: array /dev/md1 started.
# mdadm --query /dev/md1
/dev/md1: 4.00GiB raid1 2 devices, 0 spares. Use mdadm --detail for more
➥ detail.
Chapter 12 — Advanced Administration
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