StarWind Enterprise Server

By Jack Fegreus
published: Thursday, July 23 2009

Cost Effective iSCSI SANity

As a software-only product for iSCSI storage virtualization, StarWind Enterprise Server from StarWind Software provides IT with a highly cost effective means to leverage storage virtualization and help deliver critical data management services for business continuity.

With StarWind Enterprise Server, any 32-bit or 64-bit Windows Server can be used to provide iSCSI target devices capable of sharing access with multiple hosts. Most importantly, StarWind differs from many competitive offerings by including two nodes with a StarWind Enterprise Server license to support mirroring and replication. StarWind also places no limits on the storage capacity exported to clients or on the number of client connections.

The simplicity of providing virtualization with a software iSCSI SAN solution allows StarWind to fit a wide range of IT needs. For SMB sites, where direct attached storage (DAS) is dominant, IT can leverage StarWind Enterprise Server with existing Ethernet infrastructure to adopt a SAN paradigm with minimal capital expenditure (CapEx) and operating (OpEx) costs. At large enterprise sites, IT can immediately garner a positive return on investment (ROI) by leveraging StarWind Enterprise Server to extend storage consolidation to desktop systems for dramatically higher storage utilization, on-demand storage provisioning, higher data availability, booting over the SAN, and tighter risk management.

It is the virtualization of systems via a Virtual Operating Environment (VOE); however, that now garners the lion's share of attention from CIOs. More importantly, to maximize the benefits of a VOE, such as VMware Virtual Infrastructure, shared SAN-based storage is a prerequisite. StarWind Enterprise Server further compounds the SAN value proposition with integrated software for the automation of storage management functions to ensure the high availability of data and protection against application outages. StarWind Enterprise Server's data management features include thin storage provisioning, data replication and migration, automated snapshots for continuous data protection, and remote mirroring for less than $3,000.

What's more, StarWind helps IT utilize storage assets more efficiently and avoid vendor lock-in. There are substantial capital costs to be paid when the same storage management functions are licensed for every storage array. Licenses for snapshot, mirror, and replication functionality will often double the cost of an array.

By building on multiple virtualization constructs, including the notion of a space of virtual disk blocks from which logical volumes are built, StarWind Enterprise Server is able to take full control over physical storage devices. In doing so, StarWind provides storage administrators with all of the tools needed to automate such critical functions as thin provisioning, creating disk snapshots, disk replication and cloning, as well as local and remote disk mirroring.

iSCSI From Desktop to VM

With server virtualization and storage consolidation the major drivers of iSCSI adoption, VSM Labs set up two servers running StarWind Enterprise Server in a VMware iSCSI SAN test scenario. We focused our tests on StarWind's ability to support a Virtual Operating Environment featuring VMware ESX server hosting 8 VMs running Windows Server 2003. With disk sharing essential for such advanced features as VMotion and VMware Consolidated Backup (VCB), the lynch pin for supporting these features with StarWind is the device sharing capability, which is dubbed "clustering" in the device creation wizard.

We began by installing StarWind Enterprise Server on a pair of Dell PowerEdge® 1900 servers: One running the 64-bit version of Windows Server 2008 and the other running the 32-bit version of Windows Server 2003. We exported all iSCSI targets using a dedicated Gigabit Ethernet adapter over a private network. Both servers were configured with an 8Gbps FC HBA and all disk block pools for iSCSI target volumes originated on volumes imported from a Xiotech Emprise 5000 system. With two, active-active, 4Gbps FC ports, the Emprise 5000 system provided a uniform storage base for StarWind that eliminated back-end storage as a potential bottleneck.

As with any SAN device, StarWind Enterprise Server is about packaging a collection of physical disk blocks and presenting that package to a client system as a logical disk. There are several ways to do this within StarWind, which provides a complete set of tools for IT administrators to establish control of an entire iSCSI SAN infrastructure from a central point of management. The most functional and sophisticated of StarWind's storage virtualization methods provides thin storage provisioning, automated snapshot creation, and shared disk access.

VOE Support Rigors

The VSM Labs VOE was hosted on a quad-processor HP DL580 ProLiant server, on which we installed a dual-port QLogic iSCSI HBA, the QLA4052, along with a 4Gbps Fibre Channel HBA. Similarly, we configured a quad-core Dell PowerEdge server, which ran Windows Server® 2003, VMware vCenter Server (a.k.a. Virtual Center), VMware Consolidated Backup (VCB), and Veritas NetBackup 6.5.3, with both a QLogic  iSCSI HBA and an 8Gbps FC HBA. In this configuration, we were able to test StarWind's ability to provide shared access to iSCSI targets, which is critical for VCB.

Best IT practices call for classic file-level backups of VMs to be augmented with image-level backups that can be moved among VOE servers to enhance business continuity. VCB provides the framework needed to support both image-level and file-level backup operations; however, VCB requires that an ESX host share logical disks with a Windows-based server and that makes VCB support an excellent test of the iSCSI SAN flexibility, ease-of-use, and I/O throughput provided by StarWind Enterprise Server.

The pivotal component in a VCB package is a VLUN driver, which is used to mount and read ESX-generated snapshots of VM disks. From the perspective of a VM and its business applications, the VCB backup window only lasts for the few seconds that the ESX Sever needs to take and later remove a snapshot of the VM's logical disk, which is represented by a vmdk file. The Windows-based proxy server uses the VLUN driver to mount the vmdk file as a read-only drive. In this way, all data during the backup process is accessed and moved over the storage network for minimal impact on production processing.

Feature-based Device Provisioning

As a full-featured, software-only, iSCSI target solution for Windows, StarWind Enterprise Server is a conceptually simple and deceptively complex application. Ostensibly, the purpose of installing StarWind Enterprise Server is to package collections of physical disk blocks and present those collections as logical disks to client systems. What complicate the StarWind equation are the plethora of full-featured services included with StarWind. The result can be a daunting initial out-of-box experience.

For IT, the business value of the StarWind solution lies in optimal resource utilization, minimal IT administration, and maximal performance. To meet that value proposition while also providing a wide array of optional features, StarWind utilizes a number of ways to package and virtualize pools of physical disk blocks.

While the menu to add a new iSCSI device is feature-centric, the eight options represent three different technologies for device virtualization. The most basic level of virtualization and simplest management task for IT involves exporting a raw physical device.

If the device uses the SCSI command set, then all StarWind needs to do is route the command and data streams. All extended functionality is provided by the device itself. This device choice is dubbed a SCSI pass-through interface (SPTI) device. If the device does not utilize the SCSI command set, such as a SATA drive, StarWind offers a Disk Bridge device that virtualizes the command set so that a non-SCSI drive or array can be employed.

To do more than just virtualize the SCSI command set, StarWind needs to virtualize disk blocks and that means leveraging NTFS on the host server. The easiest way to do this is with an image file that represents the iSCSI device, which is exactly the technology found in the free version of StarWind. It is also the virtualization technology used to provide VTL and RAID-1 mirror devices.