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How to attach and detach additional volumes to an existing C1 server

How to attach and detach additional volumes to an existing C1 server

This page shows how to attach and detach additional volumes to an existing server.

Requirements

  • You have an account and are logged into cloud.scaleway.com
  • You have configured your SSH Key
  • You have a server

Each server can have at most 15 volumes, including the root volume.
The type of disk to host your volumes use the LSSD technology: Local solid state drive, to deliver fast disk I/O.

LSSD volumes are teleported close to your server.

When you start a server for the first time, your volume files are downloaded from the volumes store to the local storage devices (LSSD).

Each time you start or stop a server, the volumes are downloaded or uploaded to the volumes store. The larger the amount of data to transfer, the longer the upload or download duration.

We work constantly on optimizing the transfer time of local storage devices to the volumes store.

There are five steps to attach a volume to an existing server

  • Create a new volume
  • Attach the volume to your server
  • Format the additional volume
  • Mount additional volumes manually
  • Mount additional volumes with fstab (automatic mount)

Important: Server must be powered off to attach or detach a volume.

Attach a volume to an existing server

In the Control Panel, click “Volumes” in the compute section.

Step 1 - Create a new volume

Click the “Create Volume” button.
You will land on the volume-creation page where you must input basic information for your volume:

  • The name of your volume
  • The volume type - LSSD (Local solid state drive)
  • The size in Go

Create new volume

Step 2 - Attach an existing volume to your instance

In the servers page, click on the server you want to attach a volume to.

Create new volume

On the server detail page click “Attach an existing volume” and select the volume to attach in the list.

Important: To detach the volume, click the Detach button.

Step 3 - Format the additional volume

If the new volume has never been formatted, you need to format the volume using mkfs before you can mount it.

For instance, the following command creates an ext4 file system on the volume:

root@c1-X-Y-Z-T:~# mkfs -t ext4 /dev/nbd1
mke2fs 1.42.9 (4-Feb-2014)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
610800 inodes, 2441406 blocks
122070 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2503999488
75 block groups
32768 blocks per group, 32768 fragments per group
8144 inodes per group
Superblock backups stored on blocks:
  32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

Step 4 - Mount your additional volume manually

To mount the device manually as /mnt/data, run the following commands:

root@c1-X-Y-Z-T:~# mkdir -p /mnt/data
root@c1-X-Y-Z-T:~# mount /dev/nbd1 /mnt/data
root@c1-X-Y-Z-T:~# ls -la /mnt/data/
total 24
drwxr-xr-x 3 root root  4096 Jan  1 00:07 .
drwxr-xr-x 3 root root  4096 Jan  1 00:07 ..
drwx------ 2 root root 16384 Jan  1 00:07 lost+found

Step 5 - Mount your additional volume with fstab (automatic mount)

To mount the additional volume automatically, you have to reference your devices in the /etc/fstab file.
/etc/fstab references all devices to mount when they are connected.

For instance to mount /dev/nbd1 device automatically to the /mnt/data directory, the /etc/fstab has the following content:

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>

/dev/nbd1 /mnt/data auto  defaults,nofail,errors=remount-ro 0 2

The configuration above mounts the /dev/nbd1 device to the /mnt/data directory with fstab default option and nofail.
nofail is set to allow the system to continue the boot sequence if the filesystem cannot be found, which if the volume is detached in the future.

Create the /mnt/data directory if it doesn’t exist.

root@c1-X-Y-Z-T:~# mkdir -p /mnt/data

To check devices are mounted properly, run the mount -a command to mount all devices.

Important: On the next server boot, your volumes will be mounted automatically.

Now run the df -h command, this command will list all your devices and where they are mounted:

root@c1-X-Y-Z-T:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/nbd0        23G  420M   22G   2% /
none           1010M   36K 1010M   1% /dev
none            203M   80K  203M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none           1012M     0 1012M   0% /run/shm
none            100M     0  100M   0% /run/user
/dev/nbd1       9.2G  149M  8.6G   2% /mnt/data

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