This is the first of a number of posts reviewing the StarWind Enterprise Server iSCSI software target. The posts relate to version 4 of the product.
Not everyone wants or can afford to buy dedicated storage arrays, especially in current climates. So if you don’t want to spend money on a bespoke storage solution, are there any other options available? One of them might suit your budget – StarWind Enterprise Server from StarWind Software.
Classic SCSI predicates a client/server architecture for storage transactions, where the client or host is known as an initiator and the storage device as the target. This is replicated in the iSCSI architecture and today we already see free iSCSI initiator implementations in host operating systems such as the Windows family.
StarWind Enterprise Server is a software product which turns a traditional Windows server into an iSCSI Target, meaning the server can act as a storage device, serving out LUNs to other servers across the IP network. These LUNs operate exactly as iSCSI devices would if they were presented from a more expensive and dedicated storage array.
StarWind Enterprise Server installs two components; the Windows service and the management console for creating and administering iSCSI devices. Administration is pretty simple; see the screenshots below. One shows my list of devices and the second shows the starting process to creating a new iSCSI LUN, of which there are currently eight types:
- Image File Device – a standard iSCSI LUN.
- RAM Drive Device – an iSCSI LUN emulated purely in memory on the server.
- Virtual DVD Device – an ISO of a DVD-ROM, exported as an iSCSI device.
- Disk Bridge Device – a passthrough device representing a single physical disk on the server.
- Snapshot and CDP Device – an iSCSI LUN which supports PIT snapshots.
- Mirror Device – an iSCSI LUN mirrored with RAID-1 or replicated to another server.
- SPTI Device – a raw (non-emulated) version of a Disk Bridge Device.
- Virtual Tape Device – an iSCSI LUN representing a tape device.
When any of the above devices are created (excluding the RAM device), the new device is mapped to a number of files on disk. An Image File Device is created as a simple flat file with the extension .img. A Snapshot and CDP Device is created with three separate files to hold the structure, as these devices can also act as thin provisioned LUNs. I’ll discuss more on the various flavours of LUN type in a future post.
Now the first question has to be why bother using this software? In large organisations with dedicated equipment then that question is a fair one, however not every company wants or can afford to deploy storage arrays across their environment. There are scenarios where block-based storage is still required, however cost of acquisition and management precludes the deployment of traditional solutions. More important, the StarWind iSCSI target can be deployed as part of a virtual environment, leveraging the storage deployed in say, a branch VMware server to provide centralised storage resources.
So, this first post is to set the scene. In coming posts I’ll be looking in more detail at LUN allocation types, the thin provisioning aspects of StarWind Server, security, the competition and of course performance.
Disclaimer: I have no connection or relationship to StarWind Software. A free copy of the StarWind Server software was provided by the company for evaluation.