VMworld 2015: VMware released VAIO

At VMworld in San Francisco, VMware released vSphere APIs for IO filtering or VAIO (No relation with a certain laptop series). With VAIO, VMware offers a framework  to develop filters that run in ESXi and can intercept any IO requests from a guest operating system to a virtual disk. An IO will not be issued or committed to disk without being processed by IO Filters created by 3rd parties.

How does it work

IO requests moving between the guest operating system (Initiator), located in the Virtual Machine Monitor(VMM), and a virtual disk (Consumer) are filtered through a series of two IO Filters (per disk), one filter per filter class, invoked in filter class order. For example, a replication filter executes before a cache filter. Once the IO request has been filtered by all the filters for the particular disk, the IO request moves on to its destination, either the VM or the virtual disk.

Partners can develop IO Filter plug-ins to provide filtering virtual machines. Each IO Filter registers a set of callbacks with the Filter Framework, pertaining to different disk operations. If a filter fails an operation, only the filters prior to it are informed of the failure.

Any filter can complete, fail, pass, or defer an IO request. A filter will defer an IO if the filter has to do a blocking operation like sending the data over the network, but wants to allow further IOs to get processed as well. If a filter performs a blocking operation during the regular IO processing path, it would affect the IOPS of the virtual disk, since we wouldn’t be processing any further IOs until the blocking operation completes. If the filter defers an IO request, the Filter Framework will not pass the request to subsequent filters in the class order until the filter completes the request and notifies the Filter Framework that the IO may proceed.

Check out https://developercenter.vmware.com/programs/vsphere-apis-for-io-filtering for the remainder of this article.

What is vSphere APIs for IO Filtering (VAIO)

VAIO is a Framework that enables their parties (Partners) to develop filters that run in ESXi and can intercept any IO requests from a guest operating system to a virtual disk. An IO will not be issued or committed to disk without being processed by IO Filters created by 3rd parties.

Filters execute inside ESXi and not in a VM. In addition, the VAIO Framework provides centralized installation and upgrade.

The first release of vSphere APIs for IO Filtering (ESXi 6.0 Update 1) will only support and certify the Caching and Replication use cases. VMware will not certify VAIO solutions attempting to support other use cases at this time.

Caching - Will significantly increase the IOPS available, reduce latency, and increase hardware utilization rates.

Replication - Will allow the user to create VM granular replication policies for use in DR and other scenarios (ie. Snapshot)

How IO Filtering Works

IO request moving between the guest operating system (Initiator), located in the Virtual Machine Monitor(VMM), and a virtual disk (Consumer) are filtered through a series of two IO Filters (per disk), one filter per filter class, invoked in filter class order. For example, a replication filter executes before a cache filter. Once the IO request has been filtered by all the filters for the particular disk, the IO request moves on to its destination, either the VM or the virtual disk.

Partner will develop IO Filter plug-ins to provide filtering virtual machines. Each IO Filter registers a set of callbacks with the Filter Framework, pertaining to different disk operations. If a filter fails an operation, only the filters prior to it are informed of the failure.

Any filter can complete, fail, pass, or defer an IO request. A filter will defer an IO if the filter has to do a blocking operation like sending the data over the network, but wants to allow further IOs to get processed as well. If a filter performs a blocking operation during the regular IO processing path, it would affect the IOPS of the virtual disk, since we wouldn’t be processing any further IOs until the blocking operation completes. If the filter defers an IO request, the Filter Framework will not pass the request to subsequent filters in the class order until the filter completes the request and notifies the Filter Framework that the IO may proceed.

What’s in it for you

VAIO is a filtering framework that will initially allow vendors to present capabilities for caching and replication to individual VMs. This will expand over time as partners come on board to write filters for the framework, so you can imagine where this can go for topics such as security, antivirus, encryption and other areas, as the framework matures. VAIO gives us the ability to do stuff to an IO stream in a safe and certified fashion, and manage the whole thing through profiles to ensure we get a view into the IO stream’s compliance with policy!

The VAIO program itself is for partners, the benefit is for consumers who want to do policy based management of their environment and pull in the value of our partner solutions directly into per-VM and indeed per-virtual disk storage management.

Kind regards to Ken Werneburg for the input.