Previous Storage Area Network (SAN) Interview Questions

31. What is storage virtualization?
Storage virtualization is amalgamation of multiple n/w storage devices into single storage unit.

32. What is virtualization?
A technique of hiding the physical characteristics of computer resources from the way in which other system application or end user interact with those resources. Aggregation, spanning or concatenation of the combined multiple resources into larger resource pools.

33. What is Multipath I/O?
Fault tolerant technique where, there is more than one physical path between the CPU in the computer systems and its main storage devices through the buses, controllers, switches and other bridge devices connecting them.

34. What are the 3 prominent characteristics of SAS Protocol?
a) Native Command Queuing (NCQ)
b) Port Multiplier
c) Port Selector

35. What is the purpose of disk array?
Probability of unavailability of data stored on the disk array due to single point failure is totally eliminated.

36. What is disk array?
Set of high performance storage disks that can store several terabytes of data. Single disk array can support multiple points of connection to the network.

37. What are the advantages of RAID?
“Redundant Array of Inexpensive Disks”
Depending on how we configure the array, we can have the
- data mirrored [RAID 1] (duplicate copies on separate drives)
- striped [RAID 0] (interleaved across several drives), or
- parity protected [RAID 5](extra data written to identify errors).
These can be used in combination to deliver the balance of performance and reliability that the user requires.

38. How is a SAN managed?
There are many management software’s used for managing SAN's to name a few Santricity
- IBM Tivoli Storage Manager.
- CA Unicenter.
- Veritas Volumemanger.

39. Which one is the Default ID for SCSI HBA?
Generally the default ID for SCSI HBA is 7.
SCSI- Small Computer System Interface
HBA - Host Bus Adaptor

40. What is the highest and lowest priority of SCSI?
There are 16 different ID’s which can be assigned to SCSI device 7, 6, 5, 4, 3, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, 8.
Highest priority of SCSI is ID 7 and lowest ID is 8.

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50 TOP SAN – Storage Area Networks Questions and Answers

SAN Interview Questions and Answers

Read the most frequently asked 50 top Storage Area Network (SAN) interview questions and answers for freshers and experienced job interview questions pdf download free.

SAN Interview Questions and Answers List

1. What is a SAN?
SAN is short for Storage Area Network. It is a high-speed network of storage elements, similar in form and function to a LAN that establishes direct and indirect connections between multiple servers and multiple storage elements. The SAN is an extension of the server’s storage bus

2. What does a SAN do?
SANs create connectivity. SANs offer a method of attaching storage that improves data reliability, availability and performance
SAN overcomes traditional network bottlenecks by connecting in three ways:
· Server-to-storage (direct attached storage)
· Server-to-server (network attached storage)
· Storage-to-storage (SAN Attached Storage)

3. Name some of the SAN topologies and Explain each of them ?
Point-to-point, arbitrated loop, and switched fabric topologies
a) Point-to-Point
A point-to-point connection is the simplest topology. It is used when there are exactly two nodes and future expansion is not predicted. There is no sharing of the media, which allows the devices to use the total bandwidth of the link. A simple link initialization is needed before communications can begin.
b) Arbitrary Loop
Our second topology is Fiber Channel Arbitrated Loop (FC-AL). FC-AL is more useful for storage applications. It is a loop of up to 126 nodes (NL_Ports) that is managed as a shared bus. Traffic flows in one direction, carrying data frames and primitives around the loop with a total bandwidth of 400 MBps (or 200 MBps for a loop based on 2 Gbps technology).
c) Switched Fabric Loop
It applies to switches and directors that support the FC-SW standard, that is, it is not limited to switches as its name suggests. A Fibre Channel fabric is one or more fabric switches in a single, sometimes extended, configuration. Switched fabrics provide full bandwidth per port compared to the shared bandwidth per port in arbitrated loop
Implementations.

4. What’s the need for separate network for storage why LAN cannot be used?
LAN hardware and operating systems are geared to user traffic, and LANs are tuned for a fast user response to messaging requests. With a SAN, the storage units can be secured separately from the servers and totally apart from the user network enhancing storage access in data blocks (bulk data transfers), advantageous for server-less backups.

5. What is FCP?
The Fibre Channel Protocol (FCP) is the interface protocol of SCSI on Fibre Channel. It is a gigabit speed network technology primarily used for Storage Networking. Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards (INCITS), an American National Standard Institute (ANSI) accredited standards committee. It started for use primarily in the supercomputer field, but has become the standard connection type for storage area networks in enterprise storage. Despite its name, Fibre Channel signaling can run on both twisted-pair copper wire and fiber optic cables.

6.What is iSCSI ?
Internet SCSI (iSCSI) is a transport protocol that carries SCSI commands from an initiator to a target. It is a data storage networking protocol that transports standard Small Computer System Interface (SCSI) requests over the standard Transmission Control Protocol/Internet Protocol (TCP/IP) networking technology.
iSCSI enables the implementation of IP-based storage area networks (SANs), enabling customers to use the same networking technologies — for both storage and data networks. As it uses TCP/IP, iSCSI is also well suited to run over almost any physical network. By eliminating the need for a second network technology just for storage, iSCSI has the potential to lower the costs of deploying networked storage.

7.What is FCIP ?
Fibre Channel over IP (FCIP) is also known as Fibre Channel tunneling or storage tunneling. It is a method to allow the transmission of Fibre Channel
information to be tunnelled through the IP network. FCIP encapsulates Fibre Channel block data and subsequently transports it over a TCP socket. TCP/IP services are utilized to establish connectivity between remote SANs. Any congestion control and management, as well as data error and data loss recovery, is handled by TCP/IP services, and does not affect FC fabric services. The major point with FCIP is that is does not replace FC with IP, it simply allows deployments of FC fabrics using IP tunneling

8. What is iFCP
Internet Fibre Channel Protocol (iFCP) is a mechanism for transmitting data to and from Fibre Channel storage devices in a SAN, or on the Internet using TCP/IP. iFCP gives the ability to incorporate already existing SCSI and Fibre Channel networks into the Internet. iFCP is able to be used in tandem with existing Fibre Channel protocols, such as FCIP, or it can replace them. Whereas FCIP is a tunneled solution, iFCP is an FCP routed solution.iFCP is a gateway-to-gateway protocol, and does not simply encapsulate FC block data. Gateway devices are used as the medium between the FC initiators and targets. As these gateways can either replace or be used in tandem with existing FC fabrics, iFCP could be used to help migration from a Fibre  Channel SAN to an IP SAN, or allow a combination of both

9. What is FICON address ?
FICON generates the 24-bit FC port address field in yet another way. When communication is required from the FICON channel port to the FICON CU port,
the FICON channel (using FC-SB-2 and FC-FS protocol information) will provide both the address of its port, the source port address identifier (S_ID), and the address of the CU port, the destination port address identifier (D_ID) when the communication is from the channel N_Port to the CU N_Port.

10. What is zoning?
Fabric management service that can be used to create logical subsets of devices within a SAN. This enables portioning of resources for management and access control purpose.


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