Storage Name Service
Internet Storage Name Service (iSNS) allows for central registration of an iSCSI environment because it automatically discovers available targets on the network. The purpose of iSNS is to help find available targets on a large iSCSI network.
The Microsoft iSCSI initiator includes an iSNS client that is used to register with the iSNS. The iSNS feature maintains a database of clients that it has registered either through DCHP discovery or through manual registration. iSNS DHCP is available after the installation of the service, and it is used to allow iSNS clients to discover the location of the iSNS. However, if iSNS DHCP is not configured, iSNS clients must be registered manually with the iscsicli command.
To execute the command, launch a command prompt on a computer hosting the Microsoft iSCSI and type iscsicli addisnsserver server_name, where server_name is the name of the computer hosting iSNS. Exercise 1.9 walks you through the steps required to install the iSNS feature on Windows Server 2012 R2, and then it explains the different tabs in iSNS.
EXERCISE 1.9: Installing the iSNS Feature on Windows Server 2012 R2
1. Choose Server Manager by clicking the Server Manager icon on the Taskbar.
2. Click number 2 ➢ Add Roles And Features.
3. Choose role-based or featured-based installation and click Next.
4. Choose your server and click Next.
5. Click Next on the Roles screen.
6. On the Select Features screen, choose the iSNS Server Service check box. Click Next.
7. On the Confirmation screen, click the Install button.
8. Click the Close button. Close Server Manager and reboot.
9. Log in and open the iSNS server under Administrative Tools.
10. Click the General tab. This tab displays the list of registered initiators and targets. In addition to their iSCSI qualified name, it lists storage node type (Target or Initiator), alias string, and entity identifier (the Fully Qualified Domain Name [FQDN] of the machine hosting the iSNS client).
11. Click the Discovery Domains tab. The purpose of Discovery Domains is to provide a way to separate and group nodes. This is similar to zoning in Fibre Channel. The following options are available on the Discovery Domains tab:
■ Create is used to create a new discovery domain.
■ Refresh is used to repopulate the Discovery Domain drop-down list.
■ Delete is used to delete the currently selected discovery domain.
■ Add is used to add nodes that are already registered in iSNS to the currently selected discovery domain.
■ Add New is used to add nodes by entering the iSCSI Qualified Name (iQN) of the node. These nodes do not have to be currently registered.
■ Remove Used is used to remove selected nodes from the discovery domain.
12. Click the Discovery Domain Sets tab. The purpose of discovery domain sets is to separate further discovery domains. Discovery domains can be enabled or disabled, giving administrators the ability to restrict further the visibility of all initiators and targets. The options on the Discovery Domain Sets tab are as follows:
■ The Enable check box is used to indicate the status of the discovery domain sets and to turn them off and on.
■ Create is used to create new discovery domain sets.
■ Refresh is used to repopulate the Discovery Domain Sets drop-down list.
■ Delete is used to delete the currently selected discovery domain set.
■ Add is used to add discovery domains to the currently selected discovery domain set.
■ Remove is used to remove selected nodes from the discovery domain sets.
13. Close the iSNS server.
Fibre Channel
Fibre Channel storage devices are similar to iSCSI storage devices in that they both allow block-level access to their data sets and can provide MPIO policies with the proper hardware configurations. However, Fibre Channel requires a Fibre Channel HBA, fiber-optic cables, and Fibre Channel switches to connect to a storage device.
A World Wide Name (WWN) from the Fibre Channel HBA is used from the host and device so that they can communicate directly with each other, similar to using a NIC’s MAC address. In other words, a logical unit number (LUN) is presented from a Fibre Channel storage device to the WWN of the host’s HBA. Fibre Channel has been the preferred method of storage because of the available connection bandwidth between the storage and the host.
Fibre Channel devices support 1Gb/s, 2Gb/s, and 4Gb/s connections, and they soon will support 8Gb/s connections, but now that 10Gb/s Ethernet networks are becoming more prevalent in many datacenters, iSCSI can be a suitable alternative. It is important to consider that 10Gb/s network switches can be more expensive than comparable Fibre Channel switches.
N-Port Identification Virtualization (NPIV) is a Fibre Channel facility allowing multiple n-port IDs to share a single physical N-Port. This allows multiple Fibre Channel initiators to occupy a single physical port. By using a single port, this eases hardware requirements in storage area network (SAN) design.
Network Attached Storage
The concept of a network attached storage (NAS) solution is that it is a low-cost device for storing data and serving files through the use of an Ethernet LAN connection. A NAS device accesses data at the file level via a communication protocol such as NFS, CIFS, or even HTTP, which is different from iSCSI or FC Fibre Channel storage devices that access the data at the block level. NAS devices are best used in file-storing applications, and they do not require a storage expert to install and maintain the device. In most cases, the only setup that is required is an IP address and an Ethernet connection.
Virtual Disk Service
Virtual Disk Service (VDS) was created to ease the administrative efforts involved in managing all of the various types of storage devices. Many storage hardware providers used their own applications for installation and management, and this made administering all of these various devices very cumbersome.
VDS is a set of application programming interfaces (APIs) that provides a centralized interface for managing all of the various storage devices. The native VDS API enables the management of disks and volumes at an OS level, and hardware vendor-supplied APIs manage the storage devices at a RAID level. These are known as software and hardware providers.
A software provider is host based, and it interacts with Plug and Play Manager because each disk is discovered and operates on volumes, disks, and disk partitions. VDS includes two software providers: basic and dynamic. The basic software provider manages basic disks with
