Storage options

Compute Engine offers several types of storage options for your instances. Each of the following storage options has unique price and performance characteristics:

If you are not sure which option to use, the most common solution is to add a persistent disk to your instance.

Introduction

By default, each Compute Engine instance has a single boot persistent disk (PD) that contains the operating system. When your apps require additional storage space, you can add one or more additional storage options to your instance. For cost comparisons, see disk pricing.

Zonal
standard
PD		 Regional
standard
PD		 Zonal
balanced
PD		 Regional
balanced
PD		 Zonal
SSD PD		 Regional
SSD PD		 Local SSDs Cloud Storage buckets
Storage type Efficient and reliable block storage Efficient and reliable block storage with synchronous replication across two zones in a region Cost-effective and reliable block storage Cost-effective and reliable block storage with synchronous replication across two zones in a region Fast and reliable block storage Fast and reliable block storage with synchronous replication across two zones in a region High performance local block storage Affordable object storage
Minimum capacity per disk 10 GB 200 GB 10 GB 10 GB 10 GB 10 GB 375 GB n/a
Maximum capacity per disk 64 TB 64 TB 64 TB 64 TB 64 TB 64 TB 375 GB n/a
Capacity increment 1 GB 1 GB 1 GB 1 GB 1 GB 1 GB 375 GB n/a
Maximum capacity per instance 257 TB* 257 TB* 257 TB* 257 TB* 257 TB* 257 TB* 9 TB Almost infinite
Scope of access Zone Zone Zone Zone Zone Zone Instance Global
Data redundancy Zonal Multi-zonal Zonal Multi-zonal Zonal Multi-zonal None Regional, dual-regional or multi-regional
Encryption at rest Yes Yes Yes Yes Yes Yes Yes Yes
Custom encryption keys Yes Yes Yes Yes Yes Yes No Yes
Machine type support All machine types All machine types Most machine types Most machine types Most machine types Most machine types Most machine types All machine types
How-to Add a standard persistent disk Add a regional standard persistent disk Add a balanced persistent disk Add a regional balanced persistent disk Add an SSD persistent disk Add a regional SSD persistent disk Add a local SSD Connect a bucket

* If you are considering creating a logical volume larger than 64 TB, see larger logical volume performance.

In addition to the storage options that Google Cloud provides, you can deploy alternative storage solutions on your instances.

Persistent disks

Persistent disks are durable network storage devices that your instances 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 disks are located independently from your virtual machine (VM) instances, so you can detach or move persistent disks to keep your data even after you delete your instances. Persistent disk performance scales automatically with size, so you can resize your existing persistent disks or add more persistent disks to an instance to meet your performance and storage space requirements.

Add a persistent disk to your instance when you need reliable and affordable storage with consistent performance characteristics.

Add a persistent disk to your instance

Disk types

When you configure a zonal or regional persistent disk, you must select one of the following disk types:

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.

Zonal
standard
PD		 Regional
standard
PD		 Zonal
balanced
PD		 Regional
balanced
PD		 Zonal
SSD PD		 Regional
SSD PD		 Local SSD (SCSI) Local SSD (NVMe)
Maximum sustained IOPS
Read IOPS per GB 0.75 0.75 6 6 30 30 – –
Write IOPS per GB 1.5 1.5 6 6 30 30 – –
Read IOPS per instance 7,500* 3,000* 15,000–80,000* 15,000–80,000* 15,000–100,000* 15,000–100,000* 900,000 2,400,000
Write IOPS per instance 15,000* 15,000* 15,000–30,000* 15,000–30,000* 15,000–100,000* 15,000–100,000* 800,000 1,200,000
Maximum sustained throughput (MB/s)
Read throughput per GB 0.12 0.12 0.28 0.28 0.48 0.48 – –
Write throughput per GB 0.12 0.12 0.28 0.28 0.48 0.48 – –
Read throughput per instance 240–1,200* 240–1,200* 240–1,200* 240–1,200* 240–1,200* 240–1,200* 9,360 9,360
Write throughput per instance 76–400** 38–200** 240–1,200* 120–600* 240–1,200* 120–600* 4,680 4,680
* Persistent disk IOPS and throughput performance depends on disk size, instance vCPU count, and I/O block size, among other factors.
** Persistent disks can achieve greater throughput performance on instances with more vCPUs. Read Network egress caps on write throughput.

Zonal persistent disks

Ease of use

Compute Engine handles most disk management tasks for you so that you do not need to deal with partitioning, redundant disk arrays, or subvolume management. Generally, you don't need to create larger logical volumes, but you can extend your secondary attached persistent disk capacity to 257 TB per instance and apply these practices to your persistent disks if you want. You can save time and get the best performance if you format your persistent disks with a single file system and no partition tables.

If you need to separate your data into multiple unique volumes, create additional disks rather than dividing your existing disks into multiple partitions.

When you require additional space on your persistent disks, resize your disks and resize your single file system rather than repartitioning and formatting.

Performance

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 performance scaling limits and optimization, see Block storage performance.

Standard persistent disks are efficient and economical for handling sequential read/write operations, but they aren't optimized to handle high rates of random input/output operations per second (IOPS). If your apps require high rates of random IOPS, use SSD persistent disks. SSD persistent disks are designed for single-digit millisecond latencies. Observed latency is application specific.

Compute Engine optimizes performance and scaling on persistent disks automatically. You don't need to stripe multiple disks together or pre-warm disks to get the best performance. When you need more disk space or better performance, resize your disks and possibly add more vCPUs to add more storage space, throughput, and IOPS. Persistent disk performance is based on the total persistent disk capacity attached to an instance and the number of vCPUs that the instance has.

For boot devices, you can reduce costs by using a standard persistent disk. Small, 10 GB persistent disks can work for basic boot and package management use cases. However, to ensure consistent performance for more general use of the boot device, use a balanced persistent disk as your boot disk.

Each persistent disk write operation contributes to the cumulative network egress traffic for your instance. This means that persistent disk write operations are capped by the network egress cap for your instance.

Reliability

Persistent disks have built-in redundancy to protect your data against equipment failure and to ensure data availability through datacenter maintenance events. Checksums are calculated for all persistent disk operations, so we can ensure that what you read is what you wrote.

Additionally, you can create snapshots of persistent disks to protect against data loss due to user error. Snapshots are incremental, and take only minutes to create even if you snapshot disks that are attached to running instances.

Persistent disk encryption

Compute Engine automatically encrypts your data before it travels outside of your instance to persistent disk storage space. Each persistent disk remains encrypted either with system-defined keys or with customer-supplied keys. Google distributes persistent disk data across multiple physical disks in a manner that users do not control.

When you delete a persistent disk, Google discards the cipher keys, rendering the data irretrievable. This process is irreversible.

If you want to control the encryption keys that are used to encrypt your data, create your disks with your own encryption keys.

Restrictions

  • You cannot attach a persistent disk to an instance in another project.

  • Instances with shared-core machine types are limited to a maximum of 16 persistent disks.

  • For custom machine types or predefined machine types have a minimum of 1 vCPU, you can attach up to 128 persistent disks.

  • Each persistent disk can be up to 64 TB in size, so there is no need to manage arrays of disks to create large logical volumes. Each instance can attach only a limited amount of total persistent disk space and a limited number of individual persistent disks. Predefined machine types and custom machine types have the same persistent disk limits.

  • Most instances can have up to 128 persistent disks and up to 257 TB of total persistent disk space attached. Total persistent disk space for an instance includes the size of the boot persistent disk.

  • Shared-core machine types are limited to 16 persistent disks and 3 TB of total persistent disk space.

  • Creating logical volumes larger than 64 TB might require special consideration. For more information see larger logical volume performance.

Regional persistent disks

Regional persistent disks have storage qualities that are similar to zonal persistent disks. However, regional persistent disks provide durable storage and replication of data between two zones in the same region.

If you are designing robust systems or high availability services on Compute Engine, use regional persistent disks combined with other best practices such as backing up your data using snapshots. Regional persistent disks are also designed to work with regional managed instance groups.

In the unlikely event of a zonal outage, you can usually failover your workload running on regional persistent disks to another zone by using the --force-attach flag. The --force-attach flag lets you attach the regional persistent disk to a standby VM instance even if the disk can't be detached from the original VM due to its unavailability. To learn more, see Regional persistent disk failover. You cannot force attach a zonal persistent disk to an instance.

Performance

Regional persistent disks are designed for workloads that require a lower Recovery Point Objective (RPO) and Recovery Time Objective (RTO) compared to using persistent disk snapshots.

Regional persistent disks are an option when write performance is less critical than data redundancy across multiple zones.

Like zonal persistent disks, regional persistent disks can achieve greater IOPS and throughput performance on instances with a greater number of vCPUs. For more information about this and other limitations, see SSD persistent disk performance limits.

When you need more disk space or better performance, you can resize your regional disks to add more storage space, throughput, and IOPS.

Reliability

Compute Engine replicates data of your regional persistent disk to the zones you selected when you created your disks. The data of each replica is spread across multiple physical machines within the zone to ensure redundancy.

Similar to zonal persistent disks, you can create snapshots of persistent disks to protect against data loss due to user error. Snapshots are incremental, and take only minutes to create even if you snapshot disks that are attached to running instances.

Restrictions

Local SSDs

Local SSDs are physically attached to the server that hosts your VM instance. Local SSDs have higher throughput and lower latency than standard persistent disks or SSD persistent disks. The data that you store on a local SSD persists only until the instance is stopped or deleted. Each local SSD is 375 GB in size, but you can attach a maximum of 24 local SSD partitions for a total of 9 TB per instance.

Create an instance with Local SSDs when you need a fast scratch disk or cache and don't want to use instance memory.

Create an instance with Local SSDs

Performance

Local SSDs are designed to offer very high IOPS and low latency. Unlike persistent disks, you must manage the striping on local SSDs yourself. Combine multiple local SSD partitions into a single logical volume to achieve the best local SSD performance per instance, or format local SSD partitions individually.

Local SSD performance depends on which interface you select. Local SSDs are available through both SCSI and NVMe interfaces.

The following table provides an overview of local SSD capacity and estimated performance using NVMe. To reach maximum performance limits with 16 or 24 local SSD partitions, use a VM with 32 or more vCPUs.

Storage space Partitions IOPS Throughput
(MB/s)
Read Write Read Write
3 TB 8 680,000 360,000 2,650 1,400
6 TB 16 1,600,000 800,000 6,240 3,120
9 TB 24 2,400,000 1,200,000 9,360 4,680

For more information, see Local SSD performance and Optimizing Local SSD performance.

Local SSD encryption

Compute Engine automatically encrypts your data when it is written to local SSD storage space. You can't use customer-supplied encryption keys with local SSDs.

Data persistence on Local SSDs

Please read Local SSD data persistence to learn what events preserve your Local SSD data and what events can cause your Local SSD data to be unrecoverable.

General limitations

  • You can create an instance with 16 or 24 local SSD partitions for 6 TB or 9 TB of local SSD space, respectively. This is available on instances with all N1 machine types and custom machine types. To reach the maximum IOPS limits, use a VM instance with 32 or more vCPUs.

  • Instances with shared-core machine types can't attach any local SSD partitions.

Local SSDs and machine types

You can attach Local SSDs to most machine types available on Compute Engine, unless otherwise noted. However, there are constraints around how many local SSDs you can attach based on each machine type. For example, if you are using an N2 machine type with 2 vCPUs, then, as shown in the following table, you can attach either 1, 2, 4, or 8 local SSD partitions to that VM, but you can't attach 3, 5, 6, 7, 16, or 24 partitions.

N1 machine types Number of local SSD partitions allowed per VM instance
All N1 machine types 1 to 8, 16, or 24
N2 machine types
Machine types with 2 to 10 vCPUs, inclusive 1, 2, 4, or 8
Machine types with 12 to 20 vCPUs, inclusive 2, 4, or 8
Machine types with 22 to 40 vCPUs, inclusive 4 or 8
Machine types with 42 to 80 vCPUs, inclusive 8
N2D machine types
Machine types with 2 to 16 vCPUs, inclusive 1, 2, 4, or 8
Machine types with 32 or 48 vCPUs 2, 4, or 8
Machine types with 64 or 80 vCPUs 4 or 8
Machine types with 96 to 224 vCPUs, inclusive 8
C2 machine types
Machine types with 4 or 8 vCPUs 1, 2, 4, or 8
Machine types with 16 vCPUs 2, 4, or 8
Machine types with 30 vCPUs 4 or 8
Machine types with 60 vCPUs 8

Local SSDs and preemptible VM instances

You can start a preemptible VM instance with a local SSD and Compute Engine charges you preemptible prices for the local SSD usage. Local SSDs attached to preemptible instances work like normal local SSDs, retain the same data persistence characteristics, and remain attached for the life of the instance. You can request a separate quota for preemptible local SSDs, but you can also choose to use your regular local SSD quota when creating preemptible local SSDs.

Compute Engine doesn't charge you for local SSDs if their instances are preempted in the first minute after they start running.

For more information about local SSDs, see Adding local SSDs.

Reserving Local SSDs with committed use discounts

To reserve Local SSD resources in a specific zone, see Reserving zonal resources. Reservations are required for committed-use pricing for Local SSDs.

Cloud Storage buckets

Cloud Storage buckets are the most flexible, scalable, and durable storage option for your VM instances. If your apps don't require the lower latency of Persistent Disks and Local SSDs, you can store your data in a Cloud Storage bucket.

Connect your instance to a Cloud Storage bucket when latency and throughput aren't a priority and when you must share data easily between multiple instances or zones.

Connect your instance to a Cloud Storage bucket

Performance

The performance of Cloud Storage buckets depends on the storage class that you select and the location of the bucket relative to your instance.

The standard storage class used in the same location as your instance gives performance that is comparable to persistent disks but with higher latency and less consistent throughput characteristics. The standard storage class used in a multiregional location stores your data redundantly across at least two regions within a larger multiregional location.

Nearline and coldline storage classes are primarily for long-term data archival. Unlike the standard storage class, these archival classes have minimum storage durations and read charges. Consequently, they are best for long-term storage of data that is accessed infrequently.

Reliability

All Cloud Storage buckets have built-in redundancy to protect your data against equipment failure and to ensure data availability through datacenter maintenance events. Checksums are calculated for all Cloud Storage operations to help ensure that what you read is what you wrote.

Flexibility

Unlike persistent disks, Cloud Storage buckets aren't restricted to the zone where your instance is located. Additionally, you can read and write data to a bucket from multiple instances simultaneously. For example, you can configure instances in multiple zones to read and write data in the same bucket rather than replicate the data to persistent disks in multiple zones.

Furthermore, you can mount a Cloud Storage bucket to your instance as a file system. Mounted buckets function similarly to a persistent disk when you read or write files. However, Cloud Storage buckets are object stores that don't have the same write constraints as a POSIX file system and can't be used as boot disks. Your instance can write data to a file and overwrite critical data from other instances that are also writing data to the storage object simultaneously.

Cloud Storage encryption

Compute Engine automatically encrypts your data before it travels outside of your instance to Cloud Storage buckets. You don't need to encrypt files on your instances before you write them to a bucket.

Just like persistent disks, you can encrypt buckets with your own encryption keys.

What's next