Introduction

Turbo mode is a performance optimization feature based on the SPDK technology on the HCI platform. This feature significantly improves storage IO performance by optimizing the VM IO path and reducing the virtualized resource scheduling costs. It is applicable for IO-bound business scenarios such as databases, big data analysis, and artificial intelligence. The mode balances performance with feature availability, supports the coexistence and mutual conversion of ordinary VMs and VMs with Turbo mode enabled, and allows flexible enabling based on actual service requirements.

1. Core technology: The VM runs in user space by using the SPDK and vhost technologies. This allows IO traffic to directly access hardware without going through the OS kernel, thereby reducing thread switching and data copy operations. The processing logic is optimized for different IO scenarios (direct access to virtual storage for single-depth IO, pipeline processing for high-depth IO, and splitting and concurrent fixing for large-block IO). This breaks through the traditional IO performance bottlenecks of virtualization.
2. System compatibility: The Turbo mode can be directly enabled for a Linux VM because the Linux system has built-in Virtio driver. To enable Turbo mode for a Windows VM, an ordinary VM must be created first, and vmTools must be installed.
3. Disk management: A VM with Turbo mode enabled uses disks in raw format. Thin-provisioned and pre-allocated disks do not have performance differences, so manual change of disk provisioning type is not required. After the Turbo mode is enabled, the allocation mode for the disk will be automatically converted from dynamic provisioning to thin provisioning, and disk provisioning type change for running VM is not supported.

Constraints and Restrictions

1.  Configuring backup or CDP policies or using agentless backup to enable VM backup on HCI or SCP are not supported. Third-party agent-based backup or application-layer backup is required to ensure data security.
2.  The disaster recovery feature on HCI and SCP is not supported. Application-layer or third-party disaster recovery tools must be applied if disaster recovery is required.
3.  Migrating a running VM to another datastore is not supported. Supports only migrating a running VM to another run location in the same datastore. Migrating a VM to VMware vCenter is not supported.
4.  Adding physical disks and shared virtual disks is not supported. Virtual storage is supported, while external storage or local storage is not supported.
5.  Suspending, import, and export operations are not supported. Creating VM through template link deployment is not supported, and only creating VM through full deployment is supported.
6.  The following features are not supported: disk snapshot (supports only storage based snapshot), space reclamation, and disk read caching.
7.  Huge-page memory must be enabled before configuration. (The feature is mandatory for Turbo mode. After the feature is enabled, the memory reclaiming on the VM will be automatically disabled. Memory overcommitment must be disabled to prevent VM start failure.)
8.  The disk type must be VirtIO disk (the type must be changed to VirtIO disk in advance to prevent system identification error).
9.  The VM must be in a powered off status (the hardware configuration can be edited only when the VM is powered off. vmTools must be installed in advance for Windows VMs. It is recommended to install the vmTools for Linux VMs).
10.  VMs cannot have snapshots (the Turbo mode cannot be enabled if snapshots exist. Therefore, all snapshots must be deleted first).
11.  Hardware and environment constraints: Only datastore using three or more nodes is supported.
12.  When cloning across datastores, the target datastore must use three or more nodes. Cloning when the VM is running is not supported.
13.  The Turbo mode cannot be enabled for VMs with disk encryption enabled.
14.  The encryption feature cannot be enabled for VMs with Turbo mode enabled.

Precautions

1.  Ordinary VM recovery: To disable Turbo mode, the VM must be powered off first. Click More > Disable Turbo Mode. After the Turbo mode is disabled, Huge Page Memory must be manually deselected (the disk provisioning type of thin provisioning will not be automatically recovered to dynamic provisioning).
2.  Time requirement: The storage resources must be occupied for enabling Turbo mode. Therefore, the operation must be performed during off-peak hours to prevent impacting the IO performance of other VMs.
3.  Troubleshooting for VM start failure: If the VM fails to start after the Turbo mode is enabled, first check whether memory overcommitment is disabled (sufficient full-page memory must be reserved), and check whether the disk type is Virtio disk (if not, the type must be modified).
4.  Backup requirement: Configuring backup policies for VMs with Turbo mode enabled on the platform is not supported. Third-party agent-based backup tools must be deployed in advance to prevent data loss.
5.  Migration across datastores: Cold migration must be applied for migrating VMs with Turbo mode enabled across storage. The target datastore must use three or more nodes. Confirming the compliance of the target datastore is required before migration.

Steps

Step 1.Enable platform-level Turbo service. For detailed operations, see the 1.1.1 Enable Turbo Service for VM section of the VM Configuration Guide.docx[23]. (The service takes effect immediately after enabled, and platform restart is not required).

Step 2.Preprocess the destination VM (operations on the VMs page).

1.  Log in to SCP and go to Resource Center > VMs. Locate the VM you want to enable Turbo mode for it.
2.  Make sure the VM is in Off status. (If the status is On, click More in the Operation column, select Power Off, and wait for the status to change to Off).
3.  For Windows VMs, check whether vmTools is installed (If not, power on the VM to install the VMtools and power off the VM again to proceed). This step can be skipped for Linux VMs (which have built-in VirtIO driver).
4.  Click OK to save the configuration and complete the VM hardware preprocessing.

Step 3.Step 3 Enable Turbo mode (operations on the VMs page).

1. Return to the VMs page, locate the target VM preprocessed, click More in the Operation column, and select Enable Turbo Mode.
2.  In the Message pop-up window, carefully read the feature restriction description (including restricted features and disk provisioning type change). Make sure the verification messages for enabling huge page memory and VirtIO disk are normal.
3.  Select I have understood the risks (If not selected; the operation cannot be submitted).
4.  Click OK to submit the task. The Turbo mode conversion process will be automatically triggered.