Storage Area Networks (SAN) Interview Questions and Answers - Top 76 Questions added

Below are some of the frequently asked Storage (SAN) basic interview question and answers. Check the Storage Area Networks (SAN) basic & advanced concepts page in this site to learn more SAN basics. 

These are the general SAN questions, these questions will be helpful for any Storage Vendor specific interviews.

Storage Area Networks (SAN) Basic concepts Interview Questions and Answers:

1. What is zoning?

A: Zoning is the allocation of resources for device load balancing and for selectively allowing access to data only to certain users.

2. How we can create the zoning?

A: 

1. Identify the WWPNs for the new server HBA. We can do this using Qlogic SAN Surfer or Emulex HBAnywhere,

2. create a new alias for the server HBA port cabled to that fabric.

For each storage device that the server needs access to on fabric 1 (or possibly just switch 1), create a new zone and include the new server alias and the alias for every relevant storage port on that device. Repeat if you have other storage devices (so two XIVs means two new zones).

3. Put the new zone (or zones) into the active zone set (or a clone of it) and activate it.

4. Repeat on fabric 2.

3. What is WWNN?

A: World Wide Node Name, it is 64 bit address. It is for identify the particular HBA

4. What is WWPN?

A: World Wide Port Number: It is 64 bit address; it is for port in HBA, Every port having their own WWPN.

5. What is the difference between WWNN and WWPN?

A: World Wide Node Name, it is 64 bit address. It is for identify the particular HBA

World Wide Port Number: It is 64 bit address; it is for port in HBA, Every port having their own WWPN

6. Expain synchronus, Asynchronous?

Asynchronous: A synchronous process is invoked by a request/response operation, and the result of the process is returned to the caller immediately via this operation.

Synchronous: An asynchronous process is invoked by a one-way operation and the result and any faults are returned by invoking other one-way operations. The process result is returned to the caller via a callback operation

7. New host and storage is there for that zoning also existing. What you will do in storage and how u will check whether the zoning is existing or not?

A: Physical Connectivity, Logical connectivity (zoning), Storage mapping to particular host

8. Explain about fabric services?

A: F-LOGI, P-LOGI, PR-LOGI

9. Explain zones and Zoneset?

A: ZONES: Zones can be members of different zone sets for different purposes

Zoneset: a zone set is composed of zones, which are composed of members

10. Fabric ports?

A: The fabric port (F_port) is a fabric switch port used to connect an N_port to a switch in a fiber channel topology.

11. What is Switch configuration?

A: connect switch through DB-9(Console port) port to management host run tip hard ware for windows host. 

There goto setup - ipaddrset - give IP address, Gateway, Subnet mask and finally enable the switch.

12. Expain about well known addresses (FLOGI,PLOGI)

i.FLOGI(Fabric logi):- It is the type of service when ever host connect to the Fabric ,Fabric will assign ID to the host.

ii.PLOGI(Port Logi):- It is the type of service where storage can assign a lun to hosts without access permissions.

13. How to check the status of the Switch ?

14. What is meant by port channeling?

Ans;-Channeling is where you "bond" two different physical ports together into a single connection for higher bandwidth and redundancy

15. What is SCN?

State change notification used to find hardware failures .

16. What is truncking?

Ans:-Aggregation of ISL’s is tunneling these entire process will call it as trunking.8 ISL link’s aggregation is called truncking .To increase bandwidth,speed.

17. What is Easy tiering and how it works?

Answers : For improving IOPS we can use the easy tiering. It have four steps how it works

• I/O Monitoring
• Data placement advisor
• Data migration planner
• Data Migrator
• In this concept max 2 TB of data can be migrated to the HDD’s to SSD’s

18. Step by step Zoning ?

Ans:-

i)  Alias creation

ii) Zone creation

iii) Cfg create

iv) Cfgsave

v) Cfgenable

19. How will you check storage us pinging with host are not?

Check in the storage array the mapped LUN’s are listing the host WWPN’s or not

20. Which zoning is secured ?

ANS:- Soft zoning is better and Flexible .it is done with WWN’s. When ever port failures connect to another port no need to do zoning again because wwn is unique for HBA.

21. What is storage portioning?

ANS :- It’s a logical entity consisting of one more logical drives that are shared by a group of hosts or exclusively accessed by a single host.

22. What is infiband switch bandwidth?

Ans:-InfiniBand is a switched fabric computer network communications link used in high-performance computing and enterprise data centers.

23. What is SCSI maping? SCSI masking?

Ans:-- Allocating lun to a perticular host without accessin permissions. Providing access rights to access lun to a particular host.

24. Firmware update in Brocade Switch ?

A: Firmware file download from server and update on switch

25. FC layers?

FC-4 :- ULP(upper layered Protocol) ex: fcp,fcip,icfcp

FC-3 :- Common services

FC-2 :- framing & flowcontrol

FC-1 ; - 8/10 Encoding & Decoding

FC-0 :- Physical layer Speeds and feeds)

26. FC topologies?

i) point-point

ii) FC_AL (Fiber channel – Arbitrated loop)

iii) Switched Fabric

27. What is frame ?

Ans:- Frame is a binary electrical digital data transfer between source and destination.frame size is 2148 bytes.

28. What is Priniciple switch?

Ans :-The switch which is having least domain ID in a fabric is Principal switch.

29. Before shutdown switch that what will you do?

A:Take config save ,if we want config upload.

30. What is SAN ?

Ans :-SAN is high speed networking technology used to connect host to the storage with fiber channel.

31. How can u check Error in brocade switch ?
Ans :- errshow

32. Health checks in brocade switch?
Ans :- >switchshow
>switch statusshow
>switchstatuspolicyshow
>sensorshow

33. What is failover , failback ?
Ans :- FailoverProcess of switching production to a remote. (If production server fails moves to remote site)

34. What is 24 bit addressing?
Ans :- It consists of 3 octects each of 8 bits 1st octect is for domain, 2nd octect for port ID ,
3rd octect for AL-PA(Arbitrated loop physical address)

35. What is latency ?
Ans :- Time delay to reach data from source to destination

36. FLOGI,PLOGI,PRLOG?
Ans :-
PRLOGI:- processlogi providing lun access permission to host.

37. What are the class of services?
Ans :- Class 1:-Acknowledged connection oriented service
Class2:- Acknowledged connection less service
Class3:- :- UnAcknowledged connection less service
Class4:-Fraction bandwidth connection oriented service
ClassF:-Multicast service
Class6: - Switch – switchconnection less with acknowledge service.
Here Class 2,3,f are used for san technology.

38. What is FSPF?
Ans:- Fabric shortest path first path to reach destination.

39. What is FCIP,FCOE, IFCP ?
Fibre Channel Protocol (FCP) is a transport protocol (similar to TCP used in IP networks) that predominantly transports SCSI commands over Fibre Channel
Fibre Channel over IP (FCIP or FC/IP, also known as Fibre Channel tunneling or storage tunneling) is an Internet Protocol (IP) created by the Internet
Fibre Channel over Ethernet (FCoE) is a computer network technology that encapsulates Fibre Channel frames over Ethernet networks.
iFCP (Internet Fibre Channel Protocol) is an emerging standard for extending Fibre Channel storage networks across the Internet

40. What hopcount ?
Ans :- number of (Nodes)counts to reach from source to destination

41. Tell me about Fc topology ? and what is private and public?
Fc topologies are : Point-Point, FC-AL, Switched Fabric
Private : No Fabric connection
Public : attached to a ... Channel network in which up to 126 nodes are connected in a loop topology

42. What is firmware?
A: permanent software programmed into a read-only memory.

43. What is ASIC?
Ans :- Application specific integrated circuit. It is Brocade switch processor.

44. What is SSD?
Ans :- Subsystem device driver it is a multipathing software to manage both path failover and preferred path destination.

45. What is Fabric Watch?
Ans: Fabric Watch tracks a variety of SAN fabric elements, events, and counters. Continuous monitoring of the end-to-end fabric, switches, ports, Inter-Switch Links

46. Tell me led light indication in brocade switch?
SWITCH BEACON: if it is of yellow /red then it is not working. If it indicates Green light then it’s working

47. What is NPIDV. How to assign NPIDV ?
Ans :- NodePortIDvirtualization is a technology that defines how multiple virtual servers can share a single physical fiber channel port identifier

48. What is Node?
It is an entity or device where we can connect it to the network to access services.

49. Brocade architecture?
Ans :- It consists of ASIC processor, cache , NSD RAM, Console port(DB-9) .

50. What is fabric?
Ans :- Collection of switches of same vendors or different vendors.

51. what are FC protocols?
Ans :- i)FCP
ii)FCIP
iii)IFCP
iv)FCOE

51. what are FC protocols?

Ans :- i)FCP

ii)FCIP

iii)IFCP

iv)FCOE

52. FC tolpologies?

i)Point –Point

ii)FC-AL

iii)Switched Fabric

53. Types of Logis?

Ans :- i)FLOgi

ii)PLOGI

iii)PRLOGI

54. What is ISL?

Ans:- Inter switch Link physical connection between two switches.

With E-Port .It Aggregates the bandwidth

55. How to turn on trunk port?

Ans :- >portcfgtrunk portID 1

56. How to check zone status?

Ans :- >zoneshow zonename

57. What is domain id / port ID?

Domain ID name/ID of the switch and port id means port number.

58. What is dark fiber?

Ans :- lease line cable which is established but not in use called Dark Fiber.

59. SAN topologies?

Ans :- i)Point –Point

ii)FC_AL

iii)Switched Fabric

60. Diff b/w brocade 3850 & latest Model ?

Ans : Brocade 3850 supports 16, 32 ports & 5100 supports 8 gbps -40 ports

61. How to add license in switch?

Ans :- >licenceshow

>licenceadd “key”

62. Diff b/w DAS & NAS?

DAS -> Direct Attached Storage

NAS -> Network Attached storage

63. RAID LEVELS?

RAID 0:-Concatination /Stripping min 2 disks max 8 disks

RAID 1:- Mirroring min 2 disks max 8 disks

RAID2:-Bit level striping min 2 disks max 8 disks

RAID 3 :-Byte level striping with fixed parity to perform this we need to have m in 3 disks max 15 disks

RAID 4:-Block level striping with fixed parity to perform this we need to have m in 3 disks max 15 disks

RAID 5 :- striping with Distributed parity to perform this we need to have min 3 disks max 15 disks

RAID 6:- Block level striping with Distributed parity to perform this we need to have min 4 disks max 16 disks

RAID 10: Stripped mirror to perform this we need to have min 4 disks max 16 disks

RAID 01 :-mirror stripped to perform this we need to have min 4 disks max 16 disks

64. How to take switch backup?

Ans: -by doing of >configupload

After that Through FTP we need to give server name

IPaddress

UserID:

Password:

Of target server here we can save the configuration of the switch.

65. What is port address?

FCID , it is 24 bit address contains Domain Id, Port Number & Loop Number

66. HBA ?

A: Host Bus Adapter , it resides in the Host. It is Network interface card.

67. Port swapping ?

A: it is a process of when one port is failure , the other port is changed as a communication port

68. What is meant by up streaming and down streaming?

(upstream) The ISL is an upstream path toward the principal switch of the fabric.

(downstream) The ISL is a downstream path away from the principal switch of the fabric.

(Trunk Primary) The port is the master port in a group of trunking ports.

Up If the ISL is connected and the link is up

Down No ISL is connected

69. How to start Automated config upload?

A: automate configuration

70. 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.

71. 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.

72.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.

73.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

74. 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

75. 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.

76. 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.

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