VMware and iSCSI SANs for Small to Mid size Businesses

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VMware and iSCSI SANs for Small to Mid size Businesses

Overview

Server virtualization is reaching the 50% saturation level across both large enterprises and small businesses, close to half of all organizations are using virtual servers in some capacity. Whether it be for testing and development before rolling out new application and OS upgrades, for non-critical utility servers like file & print, or for mission critical servers such as Exchange, SQL and ERP applications Virtual Machines are here to stay. VMware by far offers one of the most attractive virtualization platforms due to both their market leadership and stable, robust feature set. But without a SAN many of the time saving and higher availability features to provide greater application and system uptime are simply not available. To take advantage of VMware’s advanced features such as vMotion, HA (High Availability), DRS (Distributed Resource Scheduler) and DPM (Distributed Power Management) and provide greater uptime for Virtual Machines a SAN is necessary.



The problem with implementing a SAN for many small business customers is generally lack of budget and a misconception that SAN’s are complex, expensive, or in the lower price range only useful for the needs of a small home office. StarWind iSCSI SAN software changes the game when it comes to VMware, by providing a Windows application that can run on industry standard servers. Implementing a SAN is as easy as installing a Windows operating system and the StarWind SAN software, which can be configured as easily as formatting a new hard drive. StarWind HA (High Availability) is an ideal solution for use with VMware and has been field proven since 2003.

Why use a SAN with VMware?

What do SAN’s provide that you can’t get from Direct Attached Storage (DAS)?

What will you gain by using a SAN with VMware? A SAN will eliminate single points of failure with ESX servers. Without a SAN, if an ESX server fails, all the virtual machines stored on direct attached disks are down. The only way to bring those VM’s back online is to either get the physical ESX server powered up, or restore backups of the VM images to another physical server. A SAN isn’t just about storage either, it’s also about backups, disaster recovery (off site data replication) and most importantly with VMware it’s about what you can do with to VM to increase application availability and reduce management overhead. A SAN allows you to use VMware’s VMFS (Virtual Machine File System), which decouples VM’s from the underlying storage resources. Only by using a SAN with VMware can you move a VM between physical servers without moving the actual storage, as in the VMDK file stays in the same location on the SAN. Further, there is zero downtime when moving VM’s between servers. This provides unrivalled availability of applications and servers compared to using VMware with direct attached disks. At any time of the day, without pausing or powering down the operating system inside a VM, you can use vMotion to move VM’s between physical servers to free up more resources as needed for more critical applications, or to take a physical server off line for maintenance. vMotion is now included with entry level editions of VMware providing a basis for more advanced virtual machine management using HA ,DRS & DPM.
A SAN with dual redundant controller nodes such as StarWind HA provides for the most reliable server & storage architecture when connected to two or more ESX servers. A single point of failure is removed at every layer from the SAN switches, NICs, storage nodes, individual SAN disks and the ESX servers themselves. For the past 5 years large enterprises have been implementing SAN’s and VMware in identical configurations, spending as much as $50-$100K on just the SAN alone. StarWind Software has leveraged the capabilities of the current Microsoft Server operating system to provide enterprise class SAN features at pricing affordable to SMB, Municipal Governments and Education customers.

vMotion

vMotion enables live migration of running virtual machines from one physical host to another without any downtime. Live server migrations using vMotion improves application and server availability by performing maintenance without disrupting operations and load balancing by moving running VMs away from underperforming servers. VM’s can be moved in litterly, seconds, eliminating human errors when moving workloads between physical servers and saving days of valuable time.

VMotion works because the entire VM is stored on shared storage such as a StarWind iSCSI SAN, allowing multiple ESX host servers to access the same VM concurrently. When used without DRS, VMotion allows the VMware vSphere administrator to seamlessly move VMs from one host to another with zero downtime. This gives the administrator flexibility when maintaining physical host servers, and allows manually moving VMs run on a given host with no impact to the application or end user. VMotion cannot be implemented with Direct Attached Storage (DAS) and requires shared storage such as StarWind’s iSCSI SAN.

VMware HA (High Availability)

VMware’s HA (High Availability) allows you to gain the same benefits as server clustering without the complexity, as HA is done at the Hypervisor layer. Any VM protected by VMware’s HA that stops responding will fail over automatically and HA will restart the VM on another host. VMware HA continuously monitors all physical VMware servers and provides high availability for all applications that run inside VMs. In the event of physical host failure, the affected VMs are automatically restarted on another VMware host and, in the case of OS failure, VMware HA can restart the affected VM on the same host. VMware HA leverages iSCSI SAN shared storage. When all of your VMs are stored on a StarWind SAN, VMware HA will be able to launch the VMs (that were previously hosted on the unresponsive, failed server) on another vSphere host. The combination of StarWind iSCSI SAN and VMware HA will ensure high application and data availability across your entire virtualized IT environment helping you meet service level agreements within in your organization for critical applications.

Distributed Resource Scheduler (DRS) & Distributed Power Management (DPM)

Distributed Resource Scheduler (DRS) and Distributed Power Management (DPM) are more advanced features of VMware more commonly used with customers that have more than three ESX servers. Both of these features rely on the underlying SAN. DRS automatically moves VMs between physical hardware resources based on Administrator defined policies to ensure service levels are maintained for critical servers.

DRS optimizes the Virtualized Environment by enabling smart migration of virtual machines from one ESX host to another based on predetermined performance parameters. This makes sure that no single ESX machine is overloaded and all VMs get the physical hardware resources they need, even if the resource requirement of the VM changes.

Distributed Power Management takes the functionality of DRS and intelligently moves virtual machines over to hardware resources in a manner that frees up any physical ESX servers so they can be automatically powered down. DPM continuously optimizes power in the datacenter, any VM’s in a DRS cluster that need less resources, such as a night time or on weekends, are consolidated onto fewer servers and the remaining servers are powered off. When VM resource requirements increase DPM powers up ESX hosts back online so service levels are not disrupted. Distributed Power Management helps the IT department to reduce power and cooling costs during times of low utilization.

DRS and DPM will not work with Direct Attached Storage, both DRS & DPM require centralized storage such as that which a StarWind SAN provides.

VM Backups with a SAN

When using VMware one of the first questions you should ask yourself is how will you back up data and Virtual Machines? With VM’s and data stored on a StarWind SAN, you can still use your existing backup application to backup your data.

Many concerns exist with backups in a virtualized server environment. The most common scenario with companies is to keep doing backups the same as with physical servers, by running an agent on the guest OS running inside the VM. This strategy has some drawbacks, as more and more VM’s are capable of running on new higher powered physical server hardware, attempting to run backups on all these servers at once can introduce bottle necks as VM’s compete for network and CPU cycles on the host server. This may not be an issue for smaller environments with less than 1TB of data in a full backup, or when running say, less than 5 VM’s per server. Nonetheless it’s nice to know that a SAN can help reduce or eliminate many of these backup issues before you encounter them by backing up to tape directly from the SAN, eliminating backup storage traffic on the LAN and zero CPU overhead on ESX servers, as no backup agent is running on the VM.

The StarWind SAN also allows you to perform full volume copies for backup, testing & development needs. For a robust disaster recovery strategy StarWind can also replicate data offsite.

SAN Based Replication

Replicating data off-site is a wish list item not just for SMB customers but also for many large publicly traded companies that simply have not been able to justify the costs. Conventional SAN’s don’t help with the cost aspect, as many SAN’s that support replication can run into the $40-$50K range per site. But StarWind has the answer, with Asynchronous Replication that can be purchased for a fraction of competitors SAN offerings. When using VMware and deciding how to replicate data off site choices are to 1) Replicate at the guest OS layer using an agent, 2) Replicate at the hypervisor layer, or 3) Replicate data off site at the SAN layer. Replicating data Asynchronously off site at the SAN layer allows for granularity of minutes to hours. Using an iSCSI SAN provides a cost effective solution for Disaster Recovery, eliminating the need to purchase higher cost SAN hardware and reducing the CPU overhead of host based replication. StarWind iSCSI SAN includes asynchronous replication, and synchronous mirroring used in HA mode for a fully redundant SAN architecture.

Virtual Desktops

VMware is the #1 Virtual Machine vendor today, and is traditionally know for consolidating servers, although desktops are a prime candidate to run as VMs. In recent years the cost of vitalizing desktops hasn’t added up to a savings for small and mid-size customers that can’t take advantage of economies of scale. The most expensive aspect of virtualizing desktops has been using a SAN to ensure no single ESX server is a point of failure. And with the typical expense of SAN’s with dual controllers this has been a deal breaker for many desktop virtualization projects. With a StarWind SAN built using repurposed servers or low cost commodity servers the cost of virtualizing desktops in a small company becomes feasible, allowing for all the benefits such as using a single common OS image for each department, and providing better security on the desktop, and reducing total desktop management costs.

iSCSI and VMware

VMware ESX servers natively support iSCSI storage, allowing you to take full advantage of using Ethernet switches and NICs for the SAN fabric. Using iSCSI storage with VMware allows Administrators to utilize existing skill sets with IP networking to manage and maintain the entire IT stack from SAN to application without investing time and money with the Fibre Channel (FC) learning curve or FC hardware. Using Gigabit switches and NIC’s along with multi-pathing (MPIO) features of iSCSI storage, redundant paths for availability and performance are easily achieved. StarWind iSCSI SAN allows you to add as many NIC ports to the storage node as is required to achieve optimal performance and availability.

The simplicity of using a Windows application, referred to as a «Target», to provide iSCSI storage allows you to use the Microsoft Windows operating system as the SAN controller and have a fully functional iSCSI SAN with an easy to use and familiar user interface. Any IT administrator familiar with Windows should be able to install and configure a Windows SAN in less than 30 minutes. Microsoft is one of several companies that provide iSCSI storage software for Windows; another is our featured product the StarWind iSCSI SAN.

What can you do with a StarWind iSCSI SAN?

• Use all the features of VMware server & desktop virtualization such as vMotion, HA, DRS & DPM.
• Manage unlimited Terabytes of disk space.
• Replicate data off-site or to a local backup server.
• Turn direct attached storage into a SAN.
• Increase storage security with the iSCSI standard.

StarWind’s Enterprise Class SAN Features

StarWind turns any industry-standard x86 or x64 Windows server into fail-safe, fault-tolerant storage that will be continuously available even in the event of failure. StarWind redefines high availability storage by offering this enterprise-class technology, which was previously only available in high-end storage products, to small and midsize companies at an affordable price. This combination of true active-active high availability and affordable price is unprecedented.

The following is an example of setting up a High Availability configuration with a server cluster and two active-active storage nodes that have automatic failover and failback using VMware as an example:



StarWind's iSCSI SAN software is available as an active-active high availability (HA) configuration, or in single node configurations. The active-active HA architecture provides continuous and non-disruptive access to storage in the event of failure by synchronously replicating (mirroring) data between two active storage nodes, all in real time. HA is important to IT professionals as it eliminates a single point of failure at the storage node level, providing for zero data loss in the event of a failed storage node. If a disk, power supply or even an entire storage node fails, the remaining iSCSI storage node will take over and continue to operate without any disruption, ensuring the SAN is still available and accessible on the network.

StarWind turns any industry-standard Windows Server into a fault-tolerant, fail-safe Windows iSCSI SAN and is qualified for use with VMware, Hyper-V, XenServer and Linux and Unix environments. A StarWind iSCSI SAN is ideal for use anywhere shared storage is required such as for virtual machines, Windows server clusters or back up to disk.
Following is a summary of the key enterprise class features available with a StarWind SAN:

• High Availability / Automatic Failover: Fault tolerant active-active technology eliminates a single point of failure.
  • Failback with Fast Synchronization: Automatic failback to a working storage node.
• Replication / Mirroring
  • Remote / Asynchronous Replication: Replicate data offsite over an IP network for remote backups and disaster recovery plans.
  • Mirroring / Synchronous Data Replication: Real-time data replication between a multi-node storage cluster for a highly available SAN.
• Clones: Make full volume copies for testing / development and backup.
• High Speed Cache: Adjust the cache of each SAN controller to maximize performance. Since StarWind runs on standard x86 servers you can use as much system RAM as you have installed.

Summary

Using VMware and a StarWind HA iSCSI SAN will provide a full featured fault-tolerant infrastructure capable of running just a few virtual machines up to hundreds. Whether the goal is to virtualize servers or desktops, the combined solution of VMware and StarWind will ensure consistent data, application and server availability and uptime. A SAN allows IT departments to fully utilize VMware’s vMotion, HA, DRS and DPM features, while protecting critical data with a dual node SAN capable of replicating data off-site for backup and disaster recovery scenarios.

Download VMware High Availability Guide:

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