After creating your instance, you will most likely want to create and attach a storage volume to store all your data on. We also encourage running all your analyses on the storage volume, so that you are not using up your root volume space on your instance.

it is important to have a place to hold and process your data. The preferred way to do this is with a data volume attached to your instance. This is better than using the root volume of your instance for processing data, for multiple reasons:

• If the root volume runs out of space because it is filled up with data, it can cause the instance to become unstable, including being unable to SSH to it.
• A data volume can be more easily moved between instances. Moreover, if the existing instance needs to be rebuilt, the contents of any data volumes will not be affected.

Note that data volumes in Nimbus are not intended for long-term storage, and are not backed up. They are meant more as local scratch space for data processing. For longer-term storage, you should consider using Acacia object storage, which you can access from your Nimbus instances (see https://support.pawsey.org.au/documentation/display/US/Manage+your+Acacia+Object+Storage for further information).

Create a Data Volume

1. Log in to the Nimbus dashboard.
   
   

2. Navigate to Volumes -> Volumes, then click the + [+ Create Volume] to bring up the Create Volume buttondialogue window.
   

   Note
   You may see an existing volume already there, with a name like 91bd1e23-ce06-41e0-aeb5-41382df48170. It is most likely the root volume for your instance, and you can ignore it.

3. On the Create Volume dialog window, enter a volume name and choose a size of your choice in gigabytes, then click the Create Volume button. 
4. On
   1. Enter a volume name (it doesn't have to be unique, as long as it helps make it recognisable from your list of volumes).
      
   2. Enter a Size in gigabytes
      
   3. Click on Create Volume

Once created, it will be listed with status Available on the Volumes page.

Attach a Data Volume

1. Back on the Volumes page, click the drop-down arrow next to Edit Volume and select click Manage Attachments.
   
2. Select the an instance you want to attach this volume to.
   
   
3. Click the Attach Volume button.
   

Format and mount a filesystem

1. on Attach Volume
   

Once attached to an instance, you will see an entry appear under the Attached To column, usually in the format /dev/sdX on <your-instance-name>.

vdX versus sdX

It is worth noting that for any instances created before May 2022, all attached disks appear within the operating system with device names in the format /dev/vdX . But for those instances created after this date, the format has changed to /dev/sdX . The reason for this is a change in how the disks are presented to the instances, so that they appear as physical disks rather than virtual (for the rest of this document, if you are using an older instance, replace /dev/sdX with /dev/vdX ).

However, an unintended side-effect of this change is that these device names get swapped around between attached disks, in particular after an instance is rebooted. This swapping of names is not reflected in details presented by the Nimbus dashboard. So if a data volume is listed in the Volumes section of the dashboard as attached with the device name /dev/sdc , within the operating system that same data volume may actually be using /dev/sdb (to re-iterate, this issue does not affect older instances using /dev/vdX for device naming).

As a result, when identifying and mounting your data volumes, the preferred method is to use the UUID rather than the device name. This will be discussed later.

Create a Filesystem

Before you can start using a newly created data volume, you first need to create a filesystem on it. This is done within the instance, so you will need to log in to the instance via SSH. 

Check that you have properly attached the volume:

$ sudo fdisk -l /dev/vdc

You should see this returned:

Disk /dev/vdc: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

(Only new volumes) Format the volume:

1. First identify the data volume to be formatted. The lsblk command can be used for this, ignoring the entries with loop in the name: 

   Code Block

   $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT loop0 7:0 0 55.6M 1 loop /snap/core18/2566 loop1 7:1 0 55.6M 1 loop /snap/core18/2560 loop2 7:2 0 99.5M 1 loop /snap/go/9952 loop3 7:3 0 48M 1 loop /snap/snapd/17336 loop4 7:4 0 63.2M 1 loop /snap/core20/1623 loop5 7:5 0 63.2M 1 loop /snap/core20/1634 loop7 7:7 0 48M 1 loop /snap/snapd/17029 loop8 7:8 0 99.6M 1 loop /snap/go/9981 sda 8:0 0 40G 0 disk ├─sda1 8:1 0 39.9G 0 part / ├─sda14 8:14 0 4M 0 part └─sda15 8:15 0 106M 0 part /boot/efi sdb 8:16 0 64M 0 disk sdc 8:32 0 5G 0 disk

   
   In the above example, we have attached a 5GB data volume, so we can see that it is currently using the device name sdc (remember that this may change after rebooting, so you should check again if you restart your instance).

2. Once identified, format it into an EXT4 file system:

   Code Block
   $ sudo mkfs.ext4 /dev/vdc

   Mount the volume to a new directory called /data:

   sdc

   
   

Depending on the size of the data volume you have created, you may need to wait several seconds for the format to complete.

Mount the Filesystem

Code Blocksudo chown ubuntu /data

1. Once you have created a filesystem on your data volume, you can now look up the UUID for it: 

   Code Block
   $ sudo mkdir /data $ sudo mount /dev/vdc /data

   Check your new /data volume:

   Code Block
   $ df -h | grep vdc

Check that you can write files to your new volume:

Code Block
cd /data touch test.txt

If you see an error about 'permission denied', you most likely need to change the owner of the volume to ububtu (that's you!) with the following command

2. blkid /dev/sda1: LABEL="cloudimg-rootfs" UUID="117a31f0-8d07-42f6-b249-a932b5bfb017" TYPE="ext4" PARTUUID="af03de76-4498-42d1-845d-1335f40797bf" /dev/sda15: LABEL="UEFI" UUID="9EB4-CF73" TYPE="vfat" PARTUUID="38c1dbc6-4122-4216-955c-6332043ded3d" /dev/sdb: SEC_TYPE="msdos" LABEL="config-2" UUID="3705-E4F8" TYPE="vfat" /dev/sdc: UUID="b88679ef-61b3-49e7-baaa-0093a6211259" TYPE="ext4"

   In the above example, we know that our data volume is currently using the device name sdc , and that it is in ext4 format, so the UUID is b88679ef-61b3-49e7-baaa-0093a6211259 .
   
   

   1. If your data volume does not appear in this list, re-run it with the "-c /dev/null" flag to bypass the cache: 

      Code Block
      $ sudo blkid -c /dev/null

      
      

3. If you don't already have a directory created as a mount point for the data volume, create it now, and change the owner of it to the username you are logged in to the instance with (ubuntu in our example): 

   Code Block
   $ sudo mkdir /scratch $ sudo chown ubuntu:ubuntu /scratch

   
   

4. Now that you have both the UUID of your data volume and a mount point in the filesystem, you can mount the volume (remember, the UUID below is just an example; substitute in your own data volume's UUID):

   Code Block
   $ sudo mount UUID="b88679ef-61b3-49e7-baaa-0093a6211259" /scratch

   Make a note of this specific command line (including the UUID and the mount point specific to your data volume), so that you can re-run it if and when your instance is rebooted.
   
   

5. Use df to confirm that you can see it mounted (bottom entry in the example below):

   Code Block

   $ df -h Filesystem Size Used Avail Use% Mounted on udev 2.0G 0 2.0G 0% /dev tmpfs 395M 988K 394M 1% /run /dev/sda1 39G 18G 21G 47% / tmpfs 2.0G 0 2.0G 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 2.0G 0 2.0G 0% /sys/fs/cgroup /dev/sda15 105M 4.4M 100M 5% /boot/efi /dev/loop2 56M 56M 0 100% /snap/core18/2560 /dev/loop0 48M 48M 0 100% /snap/snapd/17336 /dev/loop1 48M 48M 0 100% /snap/snapd/17029 /dev/loop3 56M 56M 0 100% /snap/core18/2566 /dev/loop5 100M 100M 0 100% /snap/go/9952 /dev/loop4 100M 100M 0 100% /snap/go/9981 /dev/loop6 64M 64M 0 100% /snap/core20/1634 /dev/loop7 64M 64M 0 100% /snap/core20/1623 tmpfs 395M 0 395M 0% /run/user/1000 /dev/sdc 4.9G 24K 4.6G 1% /scratch

   
   

You have now successfully attached and mounted your storage data volume.

Re-mount the Data Volume After a Reboot

If your instance is

ever restarted or shut down after mounting the data volume, you will need to re-mount the volume after your

instance starts back up. To do this, simply re-run the same mount command, with the same UUID and mount point as when you first mounted it (the UUID will not change between reboots). If you do not have the data volume's UUID recorded anywhere, refer to the section "Mount the Filesystem" above for the steps on how to find it.

Resize a Volume

It is possible to resize an existing storage data volume to make it larger, if additional space is required in an instance. This option is dependent on a few things:

• You need to have sufficient volume storage quota in your project. Go to the "Overview" page on the Nimbus dashboard to see how much volume storage is available.
• You cannot resize a root volume of an instance (the volume mounted as /dev/sda1 or /dev/vda1 inside the instance). If you require a larger root volume, your only option is to delete the instance and re-create it with a larger root volume on the "Source" section during instance creation.
• You cannot shrink an existing volume. The new volume size must be larger than the old size.

Provided it meets all these requirements, you can resize a volume by the following steps:

1. Log on to the instance, and make sure that any file systems filesystems on that volume are unmounted (use "umount" if it is mounted):

   
   

   Code Block
   $ df -h $ sudo umount /datascratch

   
   

2. Leaving your instance login active, log on to the Nimbus dashboard, go to the "Volumes" page, and select "Manage Attachments" from the drop-down menu to the right of the volume
3. Click on "Detach Volume", and confirm
4. Once detached, select "Extend Volume" from the drop-down menu to the right of the volume
   
5. Enter the new size in GB (it must be larger than the current size), then click on "Extend Volume"
   
6. To re-attach the volume, select "Manage Attachments" from the drop-down menu to the right of the volume
   
7. Select the instance you want to attach it to, make a note of the value of the "Device Name" field (usually usually /dev/vdcsdc), then click on "Attach Volume"
   

   1. Go back to your active instance login from step 2, and

   make

   1. check for the UUID of that volume: 

      Code Block
      $ blkid /dev/sda1: LABEL="cloudimg-rootfs" UUID="095994dc-6b15-45a9-bb21-a1c68493be18" TYPE="ext4" PARTUUID="3632202a-4dcc-4d02-8249-d55b4719ce75" /dev/sdc: UUID="0d5a2683-2645-4b84-bad0-256d0f1693a8" TYPE="ext4"

      
      

   2. Make sure that the operating system can see the attached volume: 

      Code Block
      $ sudo fdisk -l /dev/

   vdc

   1. sdc

      
      

8. Run a file system filesystem check on the patition partition first (assuming that the partition is is /dev/vdcsdc,  although fdisk will tell you if the partition has a different name like /dev/vdc1sdc1):
   

   Code Block
   $ sudo e2fsck -f /dev/vdcsdc

   
   

9. Resize the partition to use the additional space added to the volume:
   

   Code Block
   $ sudo resize2fs /dev/vdcsdc

   
   

10. You can now mount the volume again (replace /data with scratch with the mount point you normally use for the volume):
    

    Code Block
    $ sudo mount /dev/vdc /dataUUID="0d5a2683-2645-4b84-bad0-256d0f1693a8" /scratch