What Is VMware Storage vMotion?

VMware Storage vMotion enables the live migration of running virtual machine disk files within and across storage arrays. Building on the success of VMware vMotion a production proven technology used for the live migration of virtual machines Storage vMotion relocates virtual machine disk files from one shared storage location to another shared storage location. It achieves this with zero downtime, continuous service availability and complete transaction integrity. Storage vMotion enables organizations to perform proactive storage migrations, simplify array refreshes/retirements, improve virtual machine storage performance and free up valuable storage capacity.

 

Fibre Channel

Fibre Channel, or FC, is high performance  network technology primarily used for storage networking. Fibre channal communicate between computer devices at data rare of 4Gbps, 8Gbps and 10Gbps. Fibre chanaal offers point to point, switched fabric and arbitrated  loop topology to configure storage network.

Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards (INCITS), an American National Standards Institute (ANSI)–accredited standards committee. It started use primarily in the supercomputer field, but has become the standard connection type for storage area networks (SAN) in enterprise storage. Despite its name, Fibre Channel signaling can run on both twisted pair copper wire and fiber-optic cables.

What is iSCSI?

iSCSI (for "Internet SCSI") protocol allows clients (called initiators) to send SCSI commands (CDBs) to SCSI storage devices (targets) on remote servers. It is a popularStorage Area Network (SAN) protocol, allowing organizations to consolidate storage into data center storage arrays while providing hosts (such as database and web servers) with the illusion of locally-attached disks. Unlike Fibre Channel, which requires special-purpose cabling, iSCSI can be run over long distances using existing network infrastructure.

 

iSCSI uses TCP/IP (typically TCP ports 860 and 3260). In essence, iSCSI simply allows two hosts to negotiate and then exchange SCSI commands using IP networks. By doing this, iSCSI takes a popular high-performance local storage bus and emulates it over wide-area networks, creating a storage area network (SAN). Unlike some SAN protocols, iSCSI requires no dedicated cabling; it can be run over existing switching and IP infrastructure. As a result, iSCSI is often seen as a low-cost alternative to Fibre Channel, which requires dedicated infrastructure.

Storage Virtualization

What is storage virtualization?

The best definition of virtualization is probably data abstraction. The technology involves taking multiple physical storage devices and combining them into logical storage devices or units that are presented to the operating system, applications and users. It builds a layer of abstraction above the physical storage so that data isn't tied to specific hardware devices, providing a flexible storage environment. he management of storage devices can be tedious and time-consuming. Storage virtualization helps the storage administrator perform the tasks of backup, archiving, and recovery more easily, and in less time, by disguising the actual complexity of the SAN.

Users can implement virtualization with software applications or by using hardware and software hybrid appliances. The technology can be placed on different levels of a storage area network.

 

Why do organizations need this technology?

For organizations having islands of data scattered across different departments, storage virtualization gives them the ability to view and manage multiple, networked heterogeneous storage devices as if they were a single pool of storage managed from a single console. To an operating system, the virtual storage appears as one device, regardless of the types of storage devices pooled. This also means that end enterprise-users find attaching or detaching extra storage to be easier.

Choosing the Right Storage Technology

Choosing the Right Storage Technology   – DAS, NAS or SAN?

Choosing right storage technology is top priority while deciding IT budgets of your organization. Day by day need of information storage space is exceeds then expectations.

IT personnel need to plan for more potential risk than ever before. Although the need for storage is evident, it is not always clear which solution is right for your organization. There are a variety of options available, the most prevalent being direct-attached storage (DAS), network-attached storage (NAS) and storage area networks (SAN).

 

It is important to focus on the specific needs and long-term business goals of your organization. Several key criteria to consider include:

• Capacity - the amount and type of data (file level or block level) that needs to be stored and shared
• Performance - I/O and throughput requirements
• Scalability - Long-term data growth
• Availability and Reliability - how mission-critical are your applications?
• Data protection - Backup and recovery requirements
• IT staff and resources available
• Budget concerns

Limitations of DAS

Limitations to Direct Attached Storage:

Inflexible Resource Sharing: DAS include inability to share data or unused resources with other servers.

Hardware Proliferation: More equipment means less space for other business purposes, more licensing expenses, more setup time, and more hardware to troubleshoot and fix should a failure occur.

Backup Complexity: Need to take backup of each server.

What is DAS?

Direct attached storage is the term used to differentiate non-networked storage from SAN and NAS. In direct attached storage, the hardware is connected to an individual server. There may be more than one server but storage for each server is managed separately and cannot be shared,

The main protocols used in DAS are ATA, SATA, SCSI, SAS, and Fibre Channel. Traditionally, a DAS system enables storage capacity extension for a server, while keeping high data bandwidth and access rate. A typical DAS system is made of one or more enclosures holding storage devices such as hard disk drives, and one or more controllers. The interface with the server or the workstation is made through a host bus adapter (HBA).

Disadvantages of NAS

Network Attached Storage has the following disadvantages:

 

• Heavy use of NAS will clog up the shared LAN negatively affecting the users on the LAN. Therefore NAS is not suitable for data transfer intensive applications

• Somewhat inefficient since data transfer rides on top of standard TCP/IP protocol

• Cannot offer any storage service guarantees for mission critical operations since NAS operates in a shared environment. Only local disks and SANs  can be used to provide some service guarantees..

Benefits of NAS

Benefits of Network Attached Storage -

Availability of data: Users running different types of machines and running different types of operating systems can share files.

Centralized storage, which makes it easier and cheaper to maintain, backup, and administer (comparable to DAS). Incidentally, centralized storage is more expensive than local disks on byte cost basis, but users have to do tasks such as backups and restores on their own.

Performance can be increased by NAS because the file serving is done by the NAS and not done by a server responsible for also doing other processing. The performance of NAS devices, though, depends heavily on the speed of and traffic on the network and on the amount of cache memory (RAM) on the NAS computers or devices

What is NAS?

Network-attached storage (NAS) is hard disk storage that is set up with its own network address rather than being attached to the department computer that is serving applications to a network's workstation users. By removing storage access and its management from the department server, both application programming and files can be served faster because they are not competing for the same processor resources. The network-attached storage device is attached to a local area network (typically, an Ethernet network) and assigned an IP address. File requests are mapped by the main server to the NAS file server.

 

A NAS unit is essentially a self-contained computer connected to a network, with the sole purpose of supplying file-based data storage services to other devices on the network. The operating system and other software on the NAS unit provide the functionality of data storage, file systems, and access to files, and the management of these functionalities. The unit is not designed to carry out general-purpose computing tasks, although it may technically be possible to run other software on it. NAS units usually do not have a keyboard or display, and are controlled and configured over the network, often by connecting a browser to their network address.

Disadvantage of SAN

Only disadvantage of San is much more costly to acquire than a NAS because it is a complete architecture that uses technology that is still very expensive. Often when a company figures out the TCO in terms of cost per byte, the cost can be more easily justified. 

Benefits of a SA N

SANs allow applications that move data to perform better, for example, by having the data sent directly from the source to the target device with minimal server intervention. SANs also enable new network architectures where multiple hosts access multiple storage devices connected to the same network. Using a SAN can potentially offer the following benefits:

Availability: A single copy of data is accessible to any and all hosts via multiple paths.

Reliability: Dependable data transportation ensures a low error rate, and an ability to recover from failures is provided.

Scalability: Servers and storage devices may be added independently of one another, and do not depend on proprietary systems.

Performance: Fibre Channel (the standard method for SAN interconnectivity) has a 8GBPS  bandwidth and low overhead, and it separates storage and network I/O.

Manageability: Single image of storage media simplifies management.

Need of SAN

Traditional means for connecting servers and storage can no longer satisfy today's requirements for fast access to massive amounts of data. SCSI technology uses parallel cabling which severely limits speed, distance and the number of attached storage devices. Configuring SCSI (Small Computer Systems Interface) connections to support terabytes of data is impractical. In addition, traditional server/storage connections make the server the exclusive owner of its attached storage. As computing environments move from a server centric to data centric model, access to shared data resources becomes critical. Storage Area Networks are an enabling technology that allow storage resources to be shared in order to provide continuous, faster, easier access to data.

What is a SAN?

A SAN is a dedicated network that is separate from LANs and WANs whose primary purpose is the transfer of data between computer systems and storage elements.

 A SAN can also be a storage system consisting of storage elements, storage devices, computer systems, and/or appliances, plus all control software, communicating over a network.

 SANs create new methods of attaching storage to servers. These new methods can enable great improvements in both availability and performance. Today's SANs are used to connect shared storage arrays and tape libraries to multiple servers, and are used by clustered servers for failover.