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Updated May 8, 2026 Attaching a volume happens in two halves: tell Raff which VM the volume is for (dashboard side), then format and mount it inside the OS (guest side). This page covers both.

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Before you start

  • The VM and the volume are in the same region — you can’t attach across regions
  • The VM is in active or passive state — attach works on both
  • For Linux: shell access (SSH, browser terminal, or VNC); for Windows: RDP access

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1. Attach in the dashboard

From Compute Resources → Volumes, find the volume you want to attach. Open its row’s ⋮ Actions menu and pick Attach to VM.
Volume row Actions menu when unattached, showing Attach to VM, Configure volume, and Delete options
The Attach Volume to VM dialog asks for the target VM:
Attach Volume to VM dialog with the volume name pre-filled and a Select VM dropdown plus the active/passive requirement note
Pick a VM and click Attach. The volume’s status briefly shows Provisioning while the hypervisor wires it in (this is the normal provisioning state — the VM you attached to keeps running). Once it settles, the row shows the attached VM name:
Volumes list showing the test volume now attached to the Finance VM with a Provisioning badge
Volume row Actions menu when attached, showing Detach from VM, Increase size, Take snapshot, Configure volume, Delete
The actions menu changes when a volume is attached — Detach from VM, Increase size, and Take snapshot become available; Attach to VM disappears. The dashboard side is done. The volume now shows as a block device inside the VM, but it’s raw — no partition, no filesystem. The rest of this page covers the in-guest steps; the dashboard also has a Configure volume helper that prints the same commands ready to copy — see below.

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1b. Use the Configure volume helper

Instead of writing the commands by hand, you can open Configure volume from the volume’s row actions menu. The dialog gives you OS-specific, copy-pasteable instructions tuned to your volume’s size, name, and chosen filesystem.
Mount Your Volume helper with Linux/Windows tabs, filesystem picker, and copy-pasteable ssh / lsblk / mkfs commands
Two tabs: Linux and Windows. Each gives you the exact steps in order:
  • Step 1: ssh username@your-vm-ip-address
  • Step 2: lsblk — find the new device (typically vdb, the next letter after the OS disk)
  • Step 3: sudo mkfs.<fs> /dev/<device> — format with the filesystem you picked at create time
After step 3 the helper shows the mount and /etc/fstab commands. The Windows tab points you at Disk Management instead. If you formatted automatically at create time, only the mount step is shown — formatting is already done. The instructions below are the manual reference for the same flow if you’d rather understand each step.

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2. Find the new device (Linux)

SSH in and list block devices: 
lsblk
Look for an entry that doesn’t already have a mount point. On Raff, volumes always use the virtio-blk driver, so device names follow the /dev/vd* pattern:
PositionDevice path
OS disk/dev/vda
First attached volume/dev/vdb
Second attached volume/dev/vdc
…and so on/dev/vdd, /dev/vde, …
You won’t see /dev/sd* or /dev/nvme* paths on Raff — those are different hypervisor configurations. If lsblk shows something other than vd* for your new volume, double-check you’re inside a Raff VM. If you don’t see the new device, force a re-scan: 
echo "- - -" | sudo tee /sys/class/scsi_host/host0/scan

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3. Format the volume (Linux)

mkfs destroys any existing data on the device. Run this only on new, empty volumes.
For most workloads, ext4 is the safe default. xfs is preferred for very large volumes (multi-TB) or workloads with many parallel writes. 
# ext4 (default choice)
sudo mkfs.ext4 -L data /dev/vdb

# xfs (large volumes, parallel I/O)
sudo mkfs.xfs -L data /dev/vdb
The -L data sets a filesystem label you can refer to later.

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4. Mount it (Linux)

Create a mount point and mount the volume: 
sudo mkdir -p /mnt/data
sudo mount /dev/vdb /mnt/data
Confirm: 
df -h /mnt/data

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5. Persist across reboots — /etc/fstab (Linux)

A mount command doesn’t survive reboot. Add an /etc/fstab entry. Get the volume’s UUID: 
sudo blkid /dev/vdb
# /dev/vdb: LABEL="data" UUID="b1234567-89ab-cdef-0123-456789abcdef" TYPE="ext4"
Add to /etc/fstab: 
UUID=b1234567-89ab-cdef-0123-456789abcdef  /mnt/data  ext4  defaults,nofail,x-systemd.device-timeout=10  0  2
Notes:
  • Use UUID, not /dev/vdb — device letters can change after a hot-attach reorder.
  • nofail and x-systemd.device-timeout=10 make boot tolerant of a missing volume; without them, a detached or un-attached volume can trap the boot in emergency mode.
  • For xfs, replace ext4 with xfs.
Test the entry without rebooting: 
sudo umount /mnt/data
sudo mount -a
df -h /mnt/data
If mount -a fails, fix the /etc/fstab line before rebooting — see Recover a locked-out VM if it’s already too late.

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6. Format and mount on Windows

On a Windows Server VM, attach the volume in the dashboard, then:
  1. Open Server Manager → Tools → Computer Management → Disk Management.
  2. The new disk shows as Offline and Not Initialized. Right-click → Online.
  3. Right-click the disk again → Initialize Disk. Pick GPT.
  4. Right-click the unallocated space → New Simple Volume.
  5. Walk the wizard: assign a drive letter (e.g. D:), format as NTFS, give it a label.
The volume now mounts automatically across reboots — no fstab equivalent needed.

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7. Grow a volume after resize

When you resize a volume up in the dashboard, the underlying block device grows immediately, but the filesystem doesn’t know. You need to extend it inside the VM.

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Linux — partitioned volume

# Re-read the device size
sudo partprobe /dev/vdb

# Grow the partition (only if you partitioned it)
sudo growpart /dev/vdb 1

# Extend the filesystem
sudo resize2fs /dev/vdb1     # ext4
# or
sudo xfs_growfs /mnt/data    # xfs (mountpoint, not device)

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Linux — whole-device filesystem (no partition)

If you mkfs-ed the device directly (no partition table), there’s no growpart step: 
sudo resize2fs /dev/vdb     # ext4
sudo xfs_growfs /mnt/data   # xfs

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Windows

In Disk Management, right-click the volume → Extend Volume and walk the wizard.

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8. Detach safely

Before detaching, unmount cleanly so writes flush: Linux: 
sudo umount /mnt/data
# Remove the /etc/fstab entry too — otherwise next boot waits for a missing volume
Windows:
  • In Disk Management, right-click the volume → Offline.
Then in the dashboard, detach the volume.

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Quick troubleshooting

SymptomLikely cause
lsblk doesn’t show the new deviceRe-scan SCSI host (step 2); confirm the volume attached to this VM
mount fails with wrong fs typeYou haven’t formatted yet — see step 3
df -h shows old size after resizeFilesystem hasn’t grown — run resize2fs / xfs_growfs (step 7)
Boot drops to emergency shell after /etc/fstab editBad fstab line — see Recover a locked-out VM
Volume seems detached after rebootForgot nofail or used /dev/vdb instead of UUID — fix the fstab line

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Next steps

Resize a volume

Grow a volume in the dashboard, then extend the filesystem.

Detach from a VM

Free a volume to reattach elsewhere.

Volume types

Performance tiers and persistence model.
Last modified on May 8, 2026