View source for Attach a disk to a virtual machine

[[Category:Microsoft Azure]]

In this article&nbsp;we are going to see how&nbsp;to attach and mount both new and existing disks to a Linux virtual machine through the Azure portal. The first few steps describe how to attach a disk to an existing VM, but note that a disk can be attached also when creating the VM itself.&nbsp;

&nbsp;

== Find the virtual machine ==

#Go to the&nbsp;[https://portal.azure.com/ Azure portal]&nbsp;to find the VM. Search for and select&nbsp;'''Virtual machines'''. 
#Choose the VM from the list. 
#In the&nbsp;'''Virtual machines'''&nbsp;page, under&nbsp;'''Settings''', choose&nbsp;'''Disk''' 

== Attach a new disk ==

#On the&nbsp;'''Disks'''&nbsp;pane, under&nbsp;'''Data disks''', select&nbsp;'''Create and attach a new disk'''. 
#Enter a name for your managed disk. Review the default settings, and update the&nbsp;'''Storage type''',&nbsp;'''Size (GiB)''',&nbsp;'''Encryption'''&nbsp;and&nbsp;'''Host caching'''&nbsp;as necessary. The last two are usually not needed. I would suggest to use an SSD as storage type, in order to have optimal I/O performance. 
#When you're done, select&nbsp;'''Save'''&nbsp;at the top of the page to create the managed disk and update the VM configuration 

== Attach an existing disk ==

#On the&nbsp;'''Disks'''&nbsp;pane, under&nbsp;'''Data disks''', select&nbsp;'''Attach existing disks'''. 
#Select the drop-down menu for&nbsp;'''Disk name'''&nbsp;and select a disk from the list of available managed disks. 
#Select&nbsp;'''Save'''&nbsp;to attach the existing managed disk and update the VM configuration. 

=== At this point we need to connect to the VM via terminal, find the disk, partition it and&nbsp;mount it to the file system. In simpler words, we need to create a folder that points to the disk (or a partition of it), so that everything saved within that folder will be saved on the disk&nbsp;and not somewhere else. ===

&nbsp;

== Connect to the VM to mount the disk ==

To partition, format, and mount your new disk so your Linux VM can use it, SSH into your VM. You can use the&nbsp;public IP address of the VM and the default&nbsp;username&nbsp;''azureuser'', unless you have changed it.

== Find the disk ==

Once connected to your VM, you need to find the disk. In this example, we're using&nbsp;<code>lsblk</code>&nbsp;to list the disks.

<code>lsblk -o NAME,HCTL,SIZE,MOUNTPOINT | grep -i "sd"</code>

The output should be similar to the following example:

<code>sda &nbsp; &nbsp; 0:0:0:0 &nbsp; &nbsp; &nbsp;30G<br/> ├─sda1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 29.9G /<br/> ├─sda14 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 4M<br/> └─sda15 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 106M /boot/efi<br/> sdb &nbsp; &nbsp; 1:0:1:0 &nbsp; &nbsp; &nbsp;14G<br/> └─sdb1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 14G /mnt<br/> sdc &nbsp; &nbsp; 3:0:0:0 &nbsp; &nbsp; &nbsp; 4G</code>

In this example, the disk that was added was&nbsp;<code>sdc</code>. It's a LUN 0 and is 4GB.

== Prepare a new empty disk ==

'''N.B.&nbsp;'''If you are using an existing disk that contains data, skip to “Mount the disk”. The following instructions will delete data on the disk.

If you're attaching a new disk, you need to partition the disk.

The&nbsp;<code>parted</code>&nbsp;utility can be used to partition and to format a data disk.

*Use the latest version&nbsp;<code>parted</code>&nbsp;that is available for your distro. 
*If the disk size is 2 tebibytes (TiB) or larger, you must use GPT partitioning. If disk size is under 2 TiB, then you can use either MBR or GPT partitioning. 

The following example uses&nbsp;<code>parted</code>&nbsp;on&nbsp;<code>/dev/sdc</code>, which is where the first data disk will typically be on most VMs. Replace&nbsp;<code>sdc</code>&nbsp;with the correct option for your disk. We're also formatting it using the XFS&nbsp;filesystem. Note that the&nbsp;<code>/dev/sdc</code> folder should be two steps “back” with respect to the landing folder when you SSH into Azure.

<code>sudo parted /dev/sdc --script mklabel gpt mkpart xfspart xfs 0% 100%<br/> sudo mkfs.xfs /dev/sdc1<br/> sudo partprobe /dev/sdc1</code>

== Mount the disk ==

Create a directory to mount the file system using&nbsp;<code>mkdir</code>. The following example creates a directory at&nbsp;<code>/datadrive</code>:

<code data-author-content="sudo mkdir /datadrive
">sudo mkdir /datadrive</code>

Use&nbsp;<code>mount</code>&nbsp;to then mount the filesystem. The following example mounts the&nbsp;''/dev/sdc1''&nbsp;partition to the&nbsp;<code>/datadrive</code>&nbsp;mount point:

<code data-author-content="sudo mount /dev/sdc1 /datadrive
">sudo mount /dev/sdc1 /datadrive</code>

'''N.B. Important:&nbsp;'''To ensure that the drive is remounted automatically after a reboot, it must be added to the&nbsp;''/etc/fstab''&nbsp;file. It's also highly recommended that the UUID (Universally Unique Identifier) is used in&nbsp;''/etc/fstab''&nbsp;to refer to the drive rather than just the device name (such as,&nbsp;''/dev/sdc1''). If the OS detects a disk error during boot, using the UUID avoids the incorrect disk being mounted to a given location. Remaining data disks would then be assigned those same device IDs. To find the UUID of the new drive, use the&nbsp;<code>blkid</code>&nbsp;utility:

<code data-author-content="sudo blkid
">sudo blkid</code>

The output looks similar to the following example:

<code>/dev/sda1: LABEL="cloudimg-rootfs" UUID="11111111-1b1b-1c1c-1d1d-1e1e1e1e1e1e" TYPE="ext4" PARTUUID="1a1b1c1d-11aa-1234-1a1a1a1a1a1a"<br/> /dev/sda15: LABEL="UEFI" UUID="BCD7-96A6" TYPE="vfat" PARTUUID="1e1g1cg1h-11aa-1234-1u1u1a1a1u1u"<br/> /dev/sdb1: UUID="22222222-2b2b-2c2c-2d2d-2e2e2e2e2e2e" TYPE="ext4" TYPE="ext4" PARTUUID="1a2b3c4d-01"<br/> /dev/sda14: PARTUUID="2e2g2cg2h-11aa-1234-1u1u1a1a1u1u"<br/> /dev/sdc1: UUID="33333333-3b3b-3c3c-3d3d-3e3e3e3e3e3e" TYPE="xfs" PARTLABEL="xfspart" PARTUUID="c1c2c3c4-1234-cdef-asdf3456ghjk"</code>

'''N.B.&nbsp;'''Improperly editing the&nbsp;'''/etc/fstab'''&nbsp;file could result in an unbootable system. If unsure, refer to the distribution's documentation for information on how to properly edit this file. You should create a backup of the&nbsp;'''/etc/fstab'''&nbsp;file is created before editing.&nbsp;

Next, open the&nbsp;'''/etc/fstab'''&nbsp;file in a text editor. Add a line to the end of the file, using the UUID value for the&nbsp;<code>/dev/sdc1</code>&nbsp;device that was created in the previous steps, and the mountpoint of&nbsp;<code>/datadrive</code>. Using the example from this article, the new line would look like the following:

<code>UUID=33333333-3b3b-3c3c-3d3d-3e3e3e3e3e3e &nbsp; /datadrive &nbsp; xfs &nbsp; defaults,nofail &nbsp; 1 &nbsp; 2</code>

When you're done editing the file, save and close the editor.

== Verify the disk ==

You can now use&nbsp;<code>lsblk</code>&nbsp;again to see the disk and the mountpoint.

<code data-author-content="lsblk -o NAME,HCTL,SIZE,MOUNTPOINT | grep -i " sd"="" "="">lsblk -o NAME,HCTL,SIZE,MOUNTPOINT | grep -i "sd"</code>

The output will look something like this:
<pre tabindex="0"><code data-author-content="sda     0:0:0:0      30G
├─sda1             29.9G /
├─sda14               4M
└─sda15             106M /boot/efi
sdb     1:0:1:0      14G
└─sdb1               14G /mnt
sdc     3:0:0:0       4G
└─sdc1                4G /datadrive
">sda     0:0:0:0      30G
├─sda1             29.9G /
├─sda14               4M
└─sda15             106M /boot/efi
sdb     1:0:1:0      14G
└─sdb1               14G /mnt
sdc     3:0:0:0       4G
└─sdc1                4G /datadrive
</code></pre>

You can see that&nbsp;<code>sdc</code>&nbsp;is now mounted at&nbsp;<code>/datadrive</code>.