Understand instance modes

An application instance can boot in either of these two modes: Compatibility or Enhanced. Instance modes are dependent on whether the guest operating system has paravirtualized drivers installed. Installing KVM paravirtualized drivers (that is, VirtIO) enables higher disk and network performance within an instance.

Compatibility mode

Compatibility mode instances do not have VirtIO drivers installed. This mode should be used in the following situations:
  • If the guest operating system is not in the list of operating systems supported by the ThinkAgile CP platform. For more information, see the following topic:

    Working with application instances

  • To resolve bootstrap issues when creating an instance from a template (VMDK) or an ISO that does not have VirtIO drivers installed.

For Compatibility mode instances:
  • Storage disks are exported as SATA.
  • Disk backups on Windows operating systems crash-consistent instead of application-consistent.
  • NICs are exported as Intel 1Gbps NICs which use e1000 driver.
  • Hot-plug of memory to running instances will not work.

For your convenience, ThinkAgile CP Guest Agent and VirtIO drivers are included in the Guest Tools ISO, which is mounted into all instances. It is recommended to install the Guest Agent and Virtio drivers as applicable and boot into Enhanced mode at the earliest possible convenience. For more information, see the following topic:

Install guest agent tools

Enhanced mode

For Enhanced mode instances with VirtIO drivers installed:
  • Storage disks are exported as SCSI disks.
  • Disk backups on Windows operating systems are application-consistent, if the Guest Agent is installed and responsive.
  • NICs are exported as RedHat VirtIO Network Adapters with 10Gbps link speed.
  • Hot plug of memory is available for supported guest operating systems.
Note:

FreeBSD, FreeNAS and Netscaler do not support guest agent tools.

For more information about changing the mode for an application instance, see the following topic:

Manage application instances