Basics of SAN Infrastructure
Storage Servers
A storage server is a standard, commercially available, Windows server dedicated to running SANmelody software. The storage server is configured with host bus adapters (HBAs) or network interface cards (NICs) to provide access to and from disk storage, and RAM for storage caching. The amount of memory and number and type of HBAs/NICs are determined by performance requirements. Also see the Network Connectivity section below.
With SANmelody software, one or two collaborating storage servers control pools of storage, working to allocate resources, provide mirror relationships, and monitor performance and status. From a storage server, an administrator manages the storage pools, referred to as Network Managed Volume (NMV) pools.
In the SANmelody environment, the storage server WWN is a “serial number” given to the storage server to identify it on the SAN. This is not the same as the HBA WWN for the storage server. The license file contains the WWN for the storage server. This is what is meant by “license files must be unique.”
Application Servers
Application servers are consumers of SANmelody-managed storage resources and benefit from the consolidated, advanced storage management functionality. SANmelody software works with the major open systems operating environments, including Windows, UNIX (all major brands), NetWare, Mac OS, VMware, and Linux.
Storage servers serve virtual volumes to application servers using FC or iSCSI Ethernet capability. Application servers will discover and use virtual volumes in the same manner as directly attached disks.
In order to achieve high availability, two network adapters are required and and qualified multipathing drivers are necessary on application servers to achieve automatic fail-over if one path to the mirrored virtual volume has I/O failures.
Refer to the DataCore Technical Support Web site (http://www.datacore.com/support/support_home.asp) for the latest DataCore Qualified Products List for qualified multipathing products.
Storage Devices
SANmelody software allows you to centrally manage any storage device that is qualified to work with the Microsoft Windows from JBOD (just a bunch of disks) enclosures to intelligent storage arrays. Supported interfaces include Fibre Channel, SCSI, iSCSI, IDE, ATA, SATA, SAS, and SSA.
Storage devices can connect through a SAN switch or directly to a storage server.
Basic vendor-specific configuration and installation of these storage devices should be performed as per manufacturer’s instructions. After the storage is managed by SANmelody software, no further device-specific configuration is necessary, other than for hardware maintenance or failure correction.
Also see Preparing Physical Disks for Management.
Network Connectivity
SANmelody SANs can be Fibre Channel, native iSCSI, or a hybrid of both.
In a basic configuration, several application servers running a variety of operating systems are connected to a switch; a storage server creates and serves virtual volumes via Fibre Channel or iSCSI; an additional storage server is used in a high availability configuration to mirror virtual volume information.
iSCSI-based SANs use standard network interface cards (NICs) or host bus adapters (HBAs) in servers and ethernet connectivity. SANmelody software supports Internet Protocol Version 4 (TCP/IPv4).
Adapter card ports can be configured as initiator, target, or both. Initiators originate I/O commands. Targets receive I/O commands.
In the typical storage network, switches interconnect the storage network elements in a very basic and easy to manage configuration, without using any proprietary features of the switches.
Conceptually, only three zones are needed for a basic configuration. One zone is for application servers, a second zone is for storage devices, and a third zone is for mirrors. This separation prevents servers from accessing and competing for the same disk resources. SANmelody storage servers are the only elements that participate in both zones, securely brokering all storage resource allocations, or “mappings,” between application server and disk. Most configurations include redundant switches for high availability.
SANmelody software works with IP to Fibre Channel routers that enable IP/ iSCSI connectivity to the Fibre Channel storage resources and with iSCSI.
Every port on a Fibre Channel network has a unique 8-byte identifier called the World Wide Name (WWN). This identifier is hard-coded into every Fibre Channel host bus adapter (HBA), Fibre Channel disk drive, tape drive, and so forth, that is capable of participating on a Fibre Channel network. (The WWN is similar in concept to the MAC address in Ethernet cards.)
The Soft WWN feature of SANmelody software enables Fibre Channel ports to be identified using a substitute World Wide Name (WWN). This allows for the replacement of Fibre Channel HBAs without having to remap to the WWN of the new HBA. In the event of an HBA failure or replacement, the Soft WWN of the port and node will be used for the new HBA. This feature makes channel replacement quick and simple and we highly recommend its use.
Refer to the DataCore Technical Support Web site (http://www.datacore.com/support/support_home.asp) for the latest DataCore Qualified Products List for qualified network products.