About Local SSD disks (original) (raw)
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If your workloads need high performance, low latency, temporary storage, consider using Local solid-state drive (Local SSD) disks when you create your compute instance. Local SSD disks are always-encrypted temporary solid-state storage for Compute Engine. To learn about the other disks available in Compute Engine, seeChoose a disk type.
Local SSD disks are ideal when you need storage for any of the following use cases:
- Caches or storage for transient data
- Scratch processing space for high performance computing or data analytics
- Temporary data storage like for the
tempdbsystem database for Microsoft SQL Server
Local SSD disks offer superior I/O operations per second (IOPS), and very low latency compared to the persistent storage provided byGoogle Cloud Hyperdisk andPersistent Disk. This low latency is because Local SSD disks are physically attached to the server that hosts your instance. For this same reason, Local SSD disks canprovide only temporary storage.
Because Local SSD is suitable only for temporary storage, you must store data that isn't temporary or ephemeral in nature on a Hyperdisk or Persistent Disk volume.
To use Local SSD disks with a compute instance,add Local SSD disks when you create the instance. You can't add Local SSD disks to an instance after you create it.
Types of Local SSD disks
Local SSD disks come in two types:
- Titanium SSD: Titanium SSD is a custom-designed local SSD disk that uses Titanium I/O offload processing and offers enhanced SSD security, performance, and management. Titanium offers higher storage IOPS, throughput, and lower latency than the previous generation of Local SSD. The storage-optimizedZ3 machine seriesand the general-purposeC4A machine seriesoffer local SSD storage using Titanium SSD.
Titanium SSD disks are directly attached to the compute instances inside their host server. - Local SSD: Local SSD is the original local SSD feature for Google Cloud. Each Local SSD disk attached to an instance provides 375 GiB of capacity. These disks provide higher performance than Hyperdisk or Persistent Disk. You can use either the NVMe or SCSI interface to mount Local SSD disks.
Local SSD disks are directly attached to the instances inside their host server.
Unless Titanium SSD is specifically mentioned, the term "Local SSD" applies to both Local SSD and Titanium SSD when describing features of local SSD disks.
Performance
Local SSD performance depends on several factors, including the number of attached Local SSD disks, the selected disk interface (NVMe orSCSI), and the instance's machine type. The available performance increases as you attach more Local SSD disks to your instance.
Local SSD performance by number of attached disks
The following tables list the maximum IOPS and throughput for NVMe- and SCSI-attached Local SSD disks. The metrics are listed by the total capacity of Local SSD disks attached to the instance.
Titanium SSD performance
The following table lists the performance limits for Titanium SSD disks onC4A andZ3 instances.
| Machine type | # of attachedTitanium SSD disks | Total storage space (GiB) | IOPS | Throughput (MiB/s) | |
|---|---|---|---|---|---|
| Read | Write | Read | Write | ||
| C4A (with 375 GiB disks) | |||||
| 1 | 375 | 150,000 | 75,000 | 650 | 330 |
| 2 | 750 | 300,000 | 150,000 | 1,300 | 660 |
| 4 | 1,500 | 600,000 | 300,000 | 2,600 | 1,320 |
| 6 | 2,250 | 900,000 | 450,000 | 3,900 | 1,980 |
| 10 | 3,750 | 1,500,000 | 750,000 | 6,500 | 3,300 |
| 14 | 5,250 | 2,100,000 | 1,050,000 | 9,100 | 4,620 |
| 16 | 6,000 | 2,400,000 | 1,200,000 | 10,400 | 5,280 |
| Z3 (3 TiB disks) | |||||
| 12 | 36,000 | 6,000,000 | 6,000,000 | 36,000 | 30,000 |
NVMe Local SSD performance
The following table lists the performance limits for Local SSD disks that are attached to instances using NVMe.
| # of attachedLocal SSD disks | Total storage space (GiB) | Capacity per disk (GiB) | IOPS | Throughput (MiB/s) | ||
|---|---|---|---|---|---|---|
| Read | Write | Read | Write | |||
| 1 | 375 | 375 | 170,000 | 90,000 | 660 | 350 |
| 2 | 750 | 375 | 340,000 | 180,000 | 1,320 | 700 |
| 3 | 1,125 | 375 | 510,000 | 270,000 | 1,980 | 1,050 |
| 4 | 1,500 | 375 | 680,000 | 360,000 | 2,650 | 1,400 |
| 5 | 1,875 | 375 | 680,000 | 360,000 | 2,650 | 1,400 |
| 6 | 2,250 | 375 | 680,000 | 360,000 | 2,650 | 1,400 |
| 7 | 2,625 | 375 | 680,000 | 360,000 | 2,650 | 1,400 |
| 8 | 3,000 | 375 | 680,000 | 360,000 | 2,650 | 1,400 |
| 16 | 6,000 | 375 | 1,600,000 | 800,000 | 6,240 | 3,120 |
| 24 | 9,000 | 375 | 2,400,000 | 1,200,000 | 9,360 | 4,680 |
| 32 | 12,000 | 375 | 3,200,000 | 1,600,000 | 12,480 | 6,240 |
SCSI Local SSD performance
The following table lists the performance limits for Local SSD disks that are attached to instances using SCSI.
| # of combinedLocal SSD disks | Storage space (GiB) | IOPS | Throughput (MiB/s) | ||
|---|---|---|---|---|---|
| Read | Write | Read | Write | ||
| 1 | 375 | 100,000 | 70,000 | 390 | 270 |
| 2 | 750 | 200,000 | 140,000 | 780 | 550 |
| 3 | 1,125 | 300,000 | 210,000 | 1,170 | 820 |
| 4 | 1,500 | 400,000 | 280,000 | 1,560 | 1,090 |
| 5 | 1,875 | 400,000 | 280,000 | 1,560 | 1,090 |
| 6 | 2,250 | 400,000 | 280,000 | 1,560 | 1,090 |
| 7 | 2,625 | 400,000 | 280,000 | 1,560 | 1,090 |
| 8 | 3,000 | 400,000 | 280,000 | 1,560 | 1,090 |
| 16 | 6,000 | 900,000 | 800,000 | 6,240 | 3,120 |
| 24 | 9,000 | 900,000 | 800,000 | 9,360 | 4,680 |
Configure your instance to maximize performance
To reach the stated performance levels, you must configure your compute instance as follows:
- Attach the Local SSD disks with the NVMe interface. Disks attached with the SCSI interface have lower performance.
- The following machine types also require a minimum number of vCPUs to reach these maximums:
- If your instance uses a custom Linux image, the image must use version 4.14.68 or later of the Linux kernel. If you use the public images provided by Compute Engine, you don't have to take any further action.
For additional instance and disk configuration settings that can improve Local SSD performance, seeOptimizing Local SSD performance.
For more information about selecting a disk interface, see Choose a disk interface.
Local SSD data persistence
Compute Engine preserves the data on Local SSD disks in certain scenarios, and in other cases, Compute Engine does not guarantee Local SSD data persistence.
The following information describes these scenarios and applies to each Local SSD disk attached to an instance.
Scenarios where Compute Engine persists Local SSD data
Data on Local SSD disks persist only through the following events:
- If you reboot the guest operating system.
- If you configure your instance forlive migrationand the instance goes through a host maintenance event.
- If you opt to preserve the Local SSD data when you stop or suspend the instance. This feature is inPreview.
Scenarios where Compute Engine might not persist Local SSD data
Data on Local SSD disks might be lost if ahost error occurs on the instance and Compute Engine can't reconnect the instance to the Local SSD disk within a specified time.
You can control how much time, if any, is spent attempting to recover the data with the Local SSD recovery timeout. If Compute Engine can't reconnect to the disk before the timeout expires, the instance is restarted. When the instance restarts, the Local SSD data is unrecoverable. Compute Engine attaches a blank Local SSD disk to the restarted instance.
The Local SSD recovery timeout is part of an instance's host maintenance policy. For more information, seeLocal SSD recovery timeout.
Scenarios where Compute Engine does not persist Local SSD data
Data on Local SSD disks does not persist through the following events:
- If you shut down the guest operating system and force the instance to stop.
- If you create a Spot VM orpreemptible VM and the VM goes through the preemption process.
- If you configure the instance tostop on host maintenance eventsand the instance goes through a host maintenance event.
- If you misconfigure the Local SSD so that it becomes unreachable.
- If you disable project billing, causing the instance to stop.
If Compute Engine was unable to recover an instance's Local SSD data, Compute Engine restarts the instance with a mounted and attached Local SSD disk for each previously attached Local SSD disk.
Machine series support
You can use Local SSD disks with the following machine series.
However, there are constraints around how many Local SSD disks you can attach based on each machine type. For more information, seeChoose a valid number of Local SSD disks.
Limitations
Local SSD has the following limitations:
- You can't use Local SSD disks with VMs withshared-core machine types.
- You can't attach Local SSD disks to instances that use N4, H3, M4, M2, E2, Tau T2A, or Tau T2D machine types.
- You can't use customer-supplied encryption keys or customer-managed encryption keys with Local SSD disks. Compute Engine automatically encrypts your data when it's written to Local SSD storage.
- You can't back up Local SSD disks with snapshots, clones, machine images, or images. Store important data on Hyperdisk or Persistent Disk volumes.
Local SSD encryption
Compute Engine automatically encrypts your data when it is written to Local SSD disks. You can't usecustomer-supplied encryption keyswith Local SSD disks.
Local SSD data backup
Since you can't back up Local SSD data with disk images, standard snapshots, or disk clones, Google recommends that you always store valuable data on adurable storage option.
If you need to preserve the data on a Local SSD disk, attach a Persistent Disk or Google Cloud Hyperdisk to the instance. After you mount the Persistent Disk or Hyperdisk copy the data from the Local SSD disk to the newly attached disk.
Choose a disk interface
To achieve the highest Local SSD performance, you must attach your disks to the instance with the NVMe interface. Performance is lower if you use the SCSI interface.
The disk interface you choose also depends on the machine type and OS that your instance uses. Some of the available machine types in Compute Engine allow you to choose between NVMe and SCSI interfaces, while others support either only NVMe or only SCSI. Similarly, some of the public OS images provided by Compute Engine might support both NVMe and SCSI, or only one of the two.
Disk interface support by machine type and OS image
The following pages provide more information about available machine types and supported public images, as well as performance details.
- Supported interfaces by machine types: SeeMachine series comparison. In the Choose VM properties to compare list, select Disk interface type.
- OS image: For a list of which public OS images provided by Compute Engine support SCSI or NVMe, see theInterfaces tab for each table in the operating system details documentation.
Considerations for NVMe for custom images
If your instance uses a custom Linux image, you must use version 4.14.68 or later of the Linux kernel for optimal NVMe performance.
Considerations for SCSI for custom images
If you have an existing setup that requires using a SCSI interface, consider using multi-queue SCSI to achieve better performance over the standard SCSI interface.
If you are using a custom image that you imported, seeEnable multi-queue SCSI.
Choose a valid number of Local SSD disks
Most machine types available on Compute Engine support Local SSD disks. Some machine types always include a fixed number of Local SSD disks by default, while others allow you to add specific numbers of disks. You can only add Local SSD disks when you create the instance. You can't add Local SSD disks to an instance after you create it.
For instances created using a storage-optimized Z3 machine type, each attached Titanium SSD disk has 3,000 GiB of capacity. For all other machine series, each Local SSD disk that you attach has 375 GiB of capacity.
Machine types that automatically attach Local SSD disks
The following table lists the machine types that include Local SSD disks by default, and shows how many disks are attached when you create the instance.
| Machine type | Number of Local SSD disksautomatically attached per instance |
|---|---|
| C4A using Titanium SSD | |
| Only the -lssd variants of the C4A machine types support local Titanium SSD. | |
| c4a-standard-4-lssd c4a-highmem-4-lssd | 1 |
| c4a-standard-8-lssd c4a-highmem-8-lssd | 2 |
| c4a-standard-16-lssd c4a-highmem-16-lssd | 4 |
| c4a-standard-32-lssd c4a-highmem-32-lssd | 6 |
| c4a-standard-48-lssd c4a-highmem-48-lssd | 10 |
| c4a-standard-64-lssd c4a-highmem-64-lssd | 14 |
| c4a-standard-72-lssd c4a-highmem-72-lssd | 16 |
| C3 | |
| Only the -lssd variants of the C3 machine types support Local SSD. | |
| c3-standard-4-lssd | 1 |
| c3-standard-8-lssd | 2 |
| c3-standard-22-lssd | 4 |
| c3-standard-44-lssd | 8 |
| c3-standard-88-lssd | 16 |
| c3-standard-176-lssd | 32 |
| C3D | |
| Only the -lssd variants of the C3D machine types support Local SSD. | |
| c3d-standard-8-lssd c3d-highmem-8-lssd | 1 |
| c3d-standard-16-lssd c3d-highmem-16-lssd | 1 |
| c3d-standard-30-lssd c3d-highmem-30-lssd | 2 |
| c3d-standard-60-lssd c3d-highmem-60-lssd | 4 |
| c3d-standard-90-lssd c3d-highmem-90-lssd | 8 |
| c3d-standard-180-lssd c3d-highmem-180-lssd | 16 |
| c3d-standard-360-lssd c3d-highmem-360-lssd | 32 |
| A4 | |
| a4-highgpu-8g | 32 |
| A3 Ultra | |
| a3-ultragpu-8g | 32 |
| A3 Mega | |
| a3-megagpu-8g | 16 |
| A3 High | |
| a3-highgpu-1g | 2 |
| a3-highgpu-2g | 4 |
| a3-highgpu-4g | 8 |
| a3-highgpu-8g | 16 |
| A3 Edge | |
| a3-edgegpu-8g | 16 |
| A2 Ultra | |
| a2-ultragpu-1g | 1 |
| a2-ultragpu-2g | 2 |
| a2-ultragpu-4g | 4 |
| a2-ultragpu-8g | 8 |
| Z3 instances using Titanium SSD | |
| Each disk is 3 TiB in size. | |
| z3-highmem-88 | 12 |
| z3-highmem-176 | 12 |
- You can't preserve the Local SSD data if you stop or suspend a VM that has more than 32 Local SSD disks attached.
- You can't preserve Local SSD data if you stop or suspend a VM from the Google Cloud console.
- Saving the Local SSD data is a slow process and begins only after the suspend or stop operation starts.
- If you're using Spot VMs or preemptible VMs and you opt to preserve Local SSD data during a suspend or stop operation, then the Local SSD data is lost if Compute Engine preempts the VM during the stop or suspend operation.
To learn how to preserve Local SSD data when you stop or suspend a VM, seeStop an instance with Local SSD disksandSuspend an instance with Local SSD disks, respectively.
Delete Local SSD disks
To remove or delete Local SSD disks, you must delete the VM the disks are attached to. You can't delete Local SSD disks unless you delete the VM.
Before you delete a VMthat has Local SSD disks attached, make sure that you migrate any critical data on the Local SSD disks to a Persistent Disk, Hyperdisk, or to another VM. Otherwise, the data on the Local SSD disks is permanently lost.
What's next
Learn how to Create a VM with Local SSD disks.