A Closer Look: VSAN Architecture

Posted on

By Brian Gallob, Solutions Architect, Evolving Solutions

In last week’s blog post, we walked through what’s new with VMware’s VSAN 6.0. Today, let’s take a look at how its management and performance.

VSAN Architecture

WRITES:

Each write first goes to a flash device. It is then de-staged to the data persistence tier (Magnetic disks in Hybrid architecture and flash devices in All-Flash architecture). When creating replicas, the writes for each replica to the flash devices is

VSAN WITNESS:

Witness components—those that contain only object metadata—are part of every storage object. A witness serves as a tiebreaker, to avoid split-brain behavior when availability decisions are made in the Virtual SAN cluster. Each Virtual SAN witness component also consumes 2MB of capacity.

Virtual SAN All-Flash architecture – Virtual SAN 6.0 allows the ability to create an all-flash architecture in which SSDs are used for caching as well as data persistence. In this architecture, the flash cache is used completely for write caching.

This all-flash architecture allows tiering of SSDs: a write-intensive, high endurance caching tier for the writes and a read-intensive, cost-effective SSD tier for data persistence, thereby reducing the cost of the all-flash architecture.

Virtual SAN All-Flash provides consistent, predictable performance with up to 90K IOPS/Host and sub-millisecond response times, making it ideal for tier-1 workloads or any applications that require consistent, predictable response times.

VMware

Management

Virtual SAN is managed through the vSphere Web Client and vCenter server

Virtual SAN is enabled at a cluster level and can be done by clicking a radio button

Management is all done through the web client using the same toolset that is used for vSphere

Virtual SAN integrates with the entire VMware stack, including features like vMotion, HA, DRS etc.

Virtual SAN can leverage VMware vSphere Data Protection™, and vSphere Replication™ for data protection, backup, replication, and disaster-recovery (DR) purposes. Virtual SAN interoperates with vRealize Automation and can be deployed in conjunction with VMware Horizon® View™ in VDI environments and vCenter Site Recovery Manager in DR environments.

VMware’s Storage Policy Based Management framework allows you to define storage requirements on a per-VM basis, based on the needs of the applications running in the VMs.

Simply define the amount of capacity, performance and availability for each VM

VSAN then matches those defined requirements to underlying storage infrastructure.

Unlike traditional external storage, where provisioning is done at storage array layer, in a more rigid-hardware-centric way… Virtual SAN puts the application in charge, and allows you to provision and control storage in an application-centric way

Virtual SAN software abstracts underlying hardware and automates ongoing management of the storage SLAs assigned to VMs

This simplifies storage management…. And as you will see, saves you time and money.

Rack Awareness is a new feature in VSAN 6 – Virtual SAN 6 now enables intelligent placement of virtual machine objects across server racks for enhanced application availability even in case of complete rack failures.

Of course, VSAN can also tolerate disk, host, and network failures (like before in VSAN 5.5).

Virtual SAN allows you to either scale up or scale out your cluster

Scale-out

  • Add another server to add capacity and performance
  • Each server contributes HDD to increase capacity and an SSD to contribute performance

Scale-up

  • Scale up for capacity by adding more HDDs
  • Scale up for performance by adding more SSDs

The end result is you are able to elastically and granular scale your storage system in a non-disruptive way

Effective for building out what you need and modularizes your datacenter

Eliminates need to make large upfront investments and gives you linear predictability for forecasting.

Some of our customers really like this functionality given the trend towards distributed / scale-out applications

Virtual SAN 6.0 doubles the scalability of Virtual SAN 5.5 by scaling up to 64 nodes per cluster for both hybrid and all-flash configurations.

Furthermore, Virtual SAN 6.0 improves VMs per host by more than 50% with the ability to manage up to 150 VMs/host on a hybrid configuration and 200 VMs/host in an all-flash configuration.

In addition to providing enterprise-level scale improvements, VSAN 6.0 provides extremely high and consistent performance. In hybrid architecture, VSAN can provide up to 40K IOPS/host, reflecting a 2x improvement over the first release of VSAN.

All-Flash architecture is specially designed to provide high performance with predictably low latencies. It can provide up to 90K IOPS/host.

Performance

Enterprise-grade Snapshots – The release introduces a high performance and efficient snapshot capability increasing the snapshot depth to 32 per virtual machine while minimizing the performance overhead

Take hourly, daily snaps for better data protection and availability

Virtual SAN scales to 32 nodes and 2M IOPs, but it does so in a predictable and linear fashion

This is particularly helpful if you are trying to forecast storage capacity, or have a latent application in need of more performance

Virtual SAN gives you the ability to granularly scale-up or scale-out your cluster

Add more resources to achieve an intended outcome

One customer quote I liked from the beta was … “We can customize IO and capacity on demand”

Linear and Predictable performance

  • Scales with your environment
  • Same functionality across different types of workloads

High VM density in VDI environments.

  • Performance isn’t a constraint
  • VSAN has VM densities comparable to an all-flash array

Summary

  • Virtual SAN scales to the needs of your environment
  • Powerful storage tier running on heterogeneous server hardware
  • 32 node VSAN cluster
  • 4.4 TBs of capacity
  • 2M IOPs
  • 3,200 VMs
  • Enterprise-grade persistent storage
  • Ideal and viable storage tier for vSphere environments
  • VSAN is high performance, scalable and resilient.

VMware VSAN – What’s New

Posted on

By Brian Gallob, Solutions Architect, Evolving Solutions

Virtual SAN is VMware’s software-defined storage solution, built from the ground up for vSphere virtual machines. It abstracts and aggregates locally attached disks in a vSphere cluster to create a storage solution that can be provisioned and managed from vCenter and the vSphere Web Client.

VSAN is hypervisor-converged – that is – storage and compute for VMs are delivered from the same x86 server platform running the hypervisor. It integrates with the entire VMware stack, including features like vMotion, HA, DRS, etc. VM storage provisioning and day-to-day management of storage SLAs can be all be controlled through VM-level policies that can be set and modified on-the-fly.

VSAN delivers enterprise-class features, scale and performance, making it the ideal storage platform for VMs.

Technical Architecture

Virtual SAN enables both hybrid and all-flash architectures.

Irrespective of the architecture, there is a flash-based caching tier which can be configured out of flash devices like SSDs, PCIe cards, Ultra DIMMs etc. The flash caching tier acts as the read cache/write buffer that dramatically improves the performance of storage operations.

In the hybrid architecture, server-attached magnetic disks are pooled to create a distributed shared datastore, which persists the data. In this type of architecture, you can get up to 30K IOPs per ESXi host.

In All-Flash architecture, the flash-based caching tier is intelligently used as a write-buffer only, while another set of SSDs forms the persistence tier to store data. Since this architecture utilizes only flash devices, it delivers extremely high IOPs of up to 90K per ESXi host, with predictable low latencies.

Hyperconverged storage solutions require the installation of a virtual storage appliance on each host. However, in the case of VSAN, because it is embedded in the ESXi kernel, all the Virtual SAN smarts are already built in to the hypervisor and there are no additional components to install. Just 2 clicks and it can be enabled. There is no separate virtual appliance and no additional management overheads.

Because it is embedded in the hypervisor VSAN provides the shortest path for I/O, making storage operations optimally efficient and does not consume CPU resources unnecessarily. Even during maintenance operations and VM migrations, storage operations are seamlessly handled.

VMware

What’s New in VSAN 6.0?

Virtual SAN 6.0 is the second-generation of VMware’s hypervisor-converged storage for VMs. Virtual SAN 6.0 capabilities are centered on delivering high performance and increased scale without compromising simplicity and cost-effectiveness.

Most notably, Virtual SAN 6.0 now allows you to create an all-flash architecture in which the VSAN datastore is carved entirely out of flash devices – i.e. SSDs are used for both caching and data persistence

In VSAN 6.0, performance has been improved with 2x more IOPS on the hybrid configuration and 4x more IOPS on All-Flash, making VSAN ideal for high performance applications which require consistent response times and low latencies

Virtual SAN 6.0 also features twice the scale, with the ability to scale to 64 ESXi hosts per VSAN cluster

In addition, VSAN 6.0 can scale to run up to 200 VMs per host representing a 50% increase over the previous version

It also features a new file system called the VSAN file system which provides efficient snapshots and clones

Rack-awareness provides the ability to tolerate rack failures for a VSAN cluster that spans multiple racks

Support for hardware controller-based checksums helps detects data corruption issues while support for hardware-based encryption can encrypt ‘data-at-rest’ for workloads that require the added level of security

With the major enhancements of this release, Virtual SAN provides both enterprise-class scale and performance as well as new capabilities that broaden the applicability of the now proven Virtual SAN technology to business critical environments.

VSAN is built from the ground up for the vSphere virtual infrastructure. With its simplicity, performance, scalability and cost-savings, VSAN is suited to be the storage for all your VMs.

VSAN is now enterprise-ready and customers can use it for a broad range of use cases, including business-critical and tier-1 production applications.

Business Proposition

Virtual SAN is built from the ground up for vSphere environments and its core value proposition comes from the following key strengths:

Radically Simple

  • It is embedded in the VM kernel and does not need to be installed like a storage appliance. Just 2 clicks and its enabled!
  • It uses storage policies to assign storage services to specific VMs. It then automatically tunes and rebalances storage to ensure that the VM storage SLAs stay compliant with the policies throughout the lifecycle of the VM.
  • It is managed through the same web interface as the rest of your vSphere environment. This makes it easy for even the VI Admin to manage storage and eliminates the need for specialized skillsets.
  • It is completed integrated into VMware stack, and works seamlessly with other vSphere features and VMware products.

High Performance

  • VSAN 6.0 uses a new flash architecture for caching and data persistence. This provides the ability to get high IOPS with consistently low latencies suitable for business-critical or transaction processing applications that require consistent response times
  • It is embedded in ESXi kernel and therefore optimizes the data I/O path better than other technologies that need a storage virtual appliance
  • One of VSAN’s core advantages is its ability to scale performance and capacity in a linear and predictable manner: both scale-out or scale-up by adding flash, magnetic disks or hosts as needed

Lowers TCO by as much as 50%

  • VSAN has a hardware independent architecture which can utilize cheaper server-side, industry-standard components to reduce storage capex; the scaling and purchasing in chunks allows the flexibility to change vendors or hardware over time, ensuring you use the latest available on the market
  • Grow-as-you-go scaling allows investments to be spread over time in a more cost-effective manner
  • Last but not least, its VMware integration, policy-driven control and automation make it operationally efficient, saving even more dollars in the long run

Check out this post: A Closer Look: VSAN Architecture where Brian examines the management and performance of VSAN architecture.