Linux – what different is there between /dev/xvdb and /dev/xvdb1

amazon-web-servicesdisk-volumelinuxpartition

I wanna make a new volume available on Linux, then I've read AWS's doc and rackspace's doc. I find that there is a little different.

AWS's doc tell the setp this:

  • format the volume mkfs -t ext4 /dev/xvdb
  • mount the volume at mount point directory “`mount /dev/xvdb /mnt/data

  • mount the volume on start

    vi /etc/fstab

    /dev/xvdb /mnt/my-data ext4 defaults,nofail 0 2

But rackspace's doc tell the step this:

  • make a partition on the volume fdisk /dev/xvdb
  • format the volume mkfs -t ext4 /dev/xvdb1
  • mount the volume at mount point directory “`mount /dev/xvdb1 /mnt/data

  • auto mount the volume on startup

    vi /etc/fstab
    /dev/xvdb1 /mnt/my-data ext4 defaults,nofail 0 2

The different is AWS use volume directly, but rackspace partition the volume and use the partiton. I wanna know if I can use the volume directly, why I need the partition? What is different between use /dev/xvdb and /dev/xvdb1?

Thank you.

Best Answer

/dev/xvdb is a disk device, and /dev/xvdb1 is first partition on a xvdb device. Although you can probably use the whole disk for a filesystem, and this may work in lot of cases (furthermore, often this is a valid approach), usually filesystems should reside inside a partition, so various utilities and software (and primarily - fsck) could recognize them by their disk label, which is set accordingly. We're tallking here about extN family of filesystems - this rule applies to them.

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