By default, each Compute Engine virtual machine (VM) instance has a single boot Persistent Disk volume that contains the operating system. When your apps require additional storage space, one possible solution is to attach additional Persistent Disk volumes to your VM.
Persistent Disk volumes are durable network storage devices that your VMs can access like physical disks in a desktop or a server. The data on each persistent disk is distributed across several physical disks. Compute Engine manages the physical disks and the data distribution for you to ensure redundancy and optimal performance.
Persistent Disk volumes are located independently from your VMs, so you can detach or move the volumes to keep your data even after you delete your instances. Persistent Disk performance scales automatically with size, so you can resize your existing Persistent Disk volumes or add more Persistent Disk volumes to a VM to meet your performance and storage space requirements.
Add a non-boot disk to your VM when you need reliable and affordable storage with consistent performance characteristics.
Add a persistent disk to your instance
257 TiB maximum capacity
Persistent Disk volumes can be up to 64 TiB in size. You can add up to 127 secondary, non-boot zonal Persistent Disk volumes to a VM instance. However, the combined total capacity of all Persistent Disk volumes attached to a single VM can't exceed 257 TiB.
You can create single logical volumes of up to 257 TiB using logical volume management inside your VM. For information about how to ensure maximum performance with large volumes, see Logical volume size.
Storage interface types
The storage interface is chosen automatically for you when you create your VM or add Persistent Disk volumes to a VM. Tau T2A and third generation VMs (such as M3) use the NVMe interface for Persistent Disk.
Confidential VM instances also use NVMe Persistent Disk. All other Compute Engine machine series use the SCSI disk interface for Persistent Disk.
Most public images include both NVMe and SCSI drivers. Most images include a
kernel with optimized drivers that allow your VM to achieve the best performance
using NVMe. Your imported Linux images achieve the best performance with NVMe if
they include kernel version 4.14.68 or later.
To determine if an operating system version supports NVMe, see the operating system details page.
Performance
Block storage resources have different performance characteristics. Consider your storage size and performance requirements to help you determine the correct block storage type for your instances. Persistent Disk performance is predictable and scales linearly with provisioned capacity until the limits for an instance's provisioned vCPUs are reached. For more information about Persistent Disk performance limits, see Performance limits for Persistent Disk.
What's next
Learn how to add a Persistent Disk volume to your VM.
Learn how to clone a Persistent Disk volume.
Learn how to share Persistent Disk volumes between VMs.
Learn how to optimize Persistent Disk performance.