The primary duties of an operating system are to manage the execution of computer processes, control the flow of data between the computer and its peripherals, and manage the data that is stored on the computer’s hard drives. Standard Operating Systems (OS), such as Windows NT and Windows 2000 require additional software to handle SAN volume sharing or file sharing. Dynamic Share provides this functionality. Lack of this functionality translates to a productivity problem for businesses.
An example is the video market, where within the workgroup, one person may be editing the video while another is editing the audio; yet another may be doing rendering, etc. These workgroups work both independently and cooperatively on the same information. Without the functionality of Dynamic Share, data sharing within the SAN work groups would lead to data corruption and reduced workflow.
The process for the video market has been to have storage connected to each station within the workgroup. Each user would have their own storage that was connected to the other stations via a standard Ethernet network. The only way to share data is to send the files across the Ethernet network or move the hard drives to the next station. When large amounts of data are transferred across an Ethernet network, even with Gigabit Ethernet, users still can’t achieve the performance of a Fibre Channel Storage Area Network or direct-attached network. The problem with both of these methods is that the original user is not able to work with their data during this process.
What Dynamic Share Does
SANs and direct-attached networks keep the data flowing and Dynamic Share provides the mechanism of sharing the information between workstations. Data storage capacity can grow as much as 50 to 100 percent annually in most companies. The inability to quickly and easily share information among platforms can impede an organization’s ability to exploit information to its fullest value. Overtaxed LANs struggle to keep up with the end-user application data flow, resulting in the creation of Storage Area Networks (SANs) or expensive and high-maintenance cluster solutions.
For SANs or clusters to effectively share the storage pools specialized software is required. Dynamic Share allows multiple SAN or network users to access and share the volumes on the centralized storage.
Dynamic Share provides cost-effective storage consolidation, enabling the creation of common shared storage pools attached to multiple servers. Dynamic Share provides the ability to share information amongst Windows NT and Windows 2000 systems and to exploit information to its fullest value.
LUN Masking
A SAN consists of shared storage, with hubs or switches and multiple workstations. Each workstation has a Fibre Channel host bus adapter (one or more depending on the high-availability requirements). One of the systems also has management software for the storage array to bind/unbind LUNs (Logical Unit Numbers), and to monitor the performance and functions of the array.
Each workstation requires an operating system. When the operating system boots up on each of the workstation, it scans for all the SCSI devices on the system and thinks that all the storage devices belong to it. To avoid overwriting of data when multiple workstations believe that the storage belongs to them, a LUN masking utility might be used.
To prevent possible data corruption that would result from multiple workstations accessing the same files on a volume, the storage management software is used to achieve LUN masking. The benefit of LUN masking is that IT managements gain the ability of doing storage consolidation, whereby each workstation “owns” its assigned disc space (LUNs).
The volumes on the storage are divided into LUNs and each workstation believes it “owns” a specific part of the storage (one or more LUNs). The disadvantages are that files cannot be safely shared amongst the workstations since they do not share the volumes.
Dynamic Share Inner Workings
To overcome the limitations of LUN masking, the user can install Dynamic Share on each of the workstations. Due to the point-to-point physical connection of the SAN and with Dynamic Share volume-sharing software, all users are able to see the volumes on the shared storage as local storage.
Each volume can have one writer at a time, while the other users on the network have reader access to that volume. Even if the writer goes offline readers still have access to the volumes. Any reader at any time can request writer access from the current owner of a volume, via commands and control messages over the Ethernet. The owner of the volume can accept or reject the request.
Once the owner of the volume relinquishes write-access privilege to another user (writer), if the writer creates or deletes any file, an automatic refresh function takes place notifying that a change has occurred on the volume.
If the writer does not write to a volume within a designated time, the volume is automatically released and write access of this volume becomes available for any other user on the network.
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