SAN jobs interview questions - Storage Area Networking job interviews Series 2

Below are the 10 questions asked in an interview with SAN company StorageTek .
1) Which are the SAN topologies?

Answer :SAN can be connected in 3 types which are mentioned below:
Point to Point topology
FC Arbitrated Loop ( FC :Fibre Channel )
Switched Fabric

2) Which are the 4 types of SAN architecture types
Answer :Core-edge
Full-Mesh
Partial-Mesh
Cascade

3) which command is used in linux to know the driver version of any hardware device ?
Answer : dmesg

4) How many minimum drives are required to create R5 ( RAID 5) ?

Answer : You need to have at least 3 disk drives to create R5.

5) Can you name some of the states of RAID array ?

Answer : There are states of RAID arrays that represent the status of the RAID arrays which are given below
online
Degraded
Rebuilding
Failed

6) Name the features of SCSI-3 standard ?

Answer : QAS: Quick arbitration and selection
Domain Validation
CRC: Cyclic redundancy check

7) Can we assign a hot spare to R0 (RAID 0)array?

Answer :No, since R0 is not redundant array, failure of any disks results in failure of the entire array so we cannot rebuild the hot spare for the R0 array.

8) Can you name some of the available tape media types ?

Answer :There are many types of tape media available to back up the data some of them are
DLT :digital linear tape - technology for tape backup/archive of networks and servers; DLT technology addresses midrange to high-end tape backup requirements.
LTO :linear tape open; a new standard tape format developed by HP, IBM, and Seagate.
AIT :advanced intelligent tape; a helical scan technology developed by Sony for tape backup/archive of networks and servers, specifically addressing midrange to high-end backup requirements.

9) what is HA ?

Answer : HA High Availability is a technology to achive failover with very less latency. Its a practical requirement of data centers these days when customers expect the servers to be running 24 hours on all 7 days around the whole 365 days a year - usually referred as 24x7x365. So to achieve this a redundant infrastructure is created to make sure if one database server or if one app server fails there is a replica Database or Appserver ready to takeover the operations. End customer never experiences any outage when there is a HA network infrastructure.

10) What is virtualization?

Answer :Virtualization is logical representation of physical devices. It is the technique of managing and presenting storage devices and resources functionally, regardless of their physical layout or location.Virtualization is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console. Storage virtualization is commonly used in a storage area network (SAN). The 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.
Virtualization is a topic of real importance and will be covered in detail in one of our future blogpost.

PLZ READ FIRST SERIES IN REAL INTERVIEW QUESTIONS AT SAN or Storage engineer position - Interview questions : Series1 ?

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This blog is aimed to help JOB seekers find a Good technology job in SAN or Storage Area Networking. We have below postings to empower you with information which makes all the difference in winning a job offer letter.

Each of the below given links contains very powerful information which you may NOT find anywhere else - So read each of these job postings & get the Winning edge.
1. What is SAN ?
2. What are the JOB opportunities in SAN ?
3. Which are the companies in SAN and How much they pay ?
4. How Can I Enter SAN industry ?
5. What are the tasks of a SAN professional- How will be a day in his office life ?
6. How will be a SAN job interview ?
7. SAN or Storage engineer position - Interview questions : Series1 ?
8. Answers for the SAN interview questions .
9. Can you tell me about some Job Openings in SAN or Storage industry?
10. Do You Want to see an Enterprise SAN infrastructure - Thanks to Dell - Watch this informative Video - See a High End Lab

THANKS TO Sun Microsystems - Video SunFire X4500 Storage Server



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Storage job interview - How will be a Real Interview

Each Company will follow a little different strategy for hiring a storage Proffessional still below information will give you a big advantage to prepare well for the actual interview.Storage is very vast technology area if you are appearing for a Storage Testing Professional's interview, Inertviewer will try to assess your abilities in the following segments.

1) Domain
2) Platforms or Operating Systems
3) Development or Testing Skills

Domain: Interviewer tries to know which part of storage you are working with or had worked earlier .You might say SAN Product test engineer,Firmware driver Test Engineer or Protocols testing Engineer. They try to assess which is your core area of working if you are a SAN Product Test Engineer they may ask about the architecture of the product ,how do you install it, how do you test it.What is the Protocols supported and what all topologies it can manage.
If you are Firmware or Driver testing engineer you will asked in Firmware and Driver model , installation ,how you test firmware for stability and their compatibilty with different OS'es.If you are Testing Protocols they might want to ask how you setup the framework for testing the protocols ,which are the tools you are using .

2) Platforms or Operating Systems.

Here they try to know how many OS's you have worked on and what extent you know them,in any company they expect you to know atlest more than 2 OS'es very well.
They might ask how you can install os'es with 3rd party drivers,how to use I/O and some configuration mangement tools.Also questions about where to find debug messeges is very frequent.

3)Core Skill :
If you were a SAN developer they might ask many questions relevant to your development aspects - questions on the programming languages, scripts, Your Configuration management etc
If you are a SAN Tester they might ask you questions on testing ,life cycles and defect tracking tools and automation tools if you know any.

VIDEO SECTION:
Thanks to DELL - Video from a Manager on NAS ( Network Attached Storage )


Storage Resume or System Administration Resume

1.What is SAN ?
2.What are the JOB opportunities in SAN ?
3.Which are the companies in SAN and How much they pay ?
4.How Can I Enter SAN industry ?
5.What are the tasks of a SAN professional- How will be a day in his office life?
6.How will be a SAN job interview ?
7.SAN or Storage engineer position - Interview questions : Series1
8.Real SAN Interview questions with answers: Series2
9.Answers for SAN interview questions Series1.
10.Tell me about some Job Openings in SAN or Storage industry?
11.Do You Want to see an Enterprise SAN infrastructure - Thanks to Dell - Watch this informative Video - See a High End Lab

Storage interview questions & answers for Series 1

We had 10 SAN interview questions in our earlier blogpost - Answers are given below

1) What is the differerence b/w SAN and NAS ?

The basic difference between SAN and NAS , SAN is Fabric based and NAS is Ethernet based.
SAN - Storage Area Network
NAS - Network attached Storage

2)What is a typical storage area network consists of - if we consider it for implementation in a small business setup ?
If we consider any small buisenss following are essentials componets of SAN

- Fabric Switch
- FC Controllers
- JBOD's

3)Can you briefly explain each of these Storage area components?
Fabric Swictch: It's a device which interconnects multiple network devices .There are swithes starting from 16 port to 32 ports which connect 16 or 32 machine nodes etc.Vendors who manufacture these kind of switches are Brocade, McData.

FC Controllers : These are Data transfer medias they will sit on PCI slots of Server,u can configure Arrays and volumes on it.

JBOD: Just Bunch of Disks is Storage Box,it consists of Enclosure where set of harddrives are hosted in many combinations such SCSI drives,SAS ,FC,SATA.

4)What is the most critical component in SAN ?
Each component has its own criticality with respect to buisness needs of a company.

5) Define RAID ? Which one you feel is good choice ?

RAID (Redundant array of Independent Disks) is a technology to achive redundancy with faster I/O.There are Many Levels of RAID to meet different needs of the customer which are : R0,R1,R5,R10,R5.
Generally customer choose R5 to achive better redundancy and speed and it is cost effective.

6)How is a SAN managed ?

There are many management softwares used for managing SAN's to name a few

- Santricity
- IBM Tivoli Storage Manager.
- CA Unicenter.
- Veritas Volumemanger.

7) 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

8) How do you install device drivers for the HBA first time during OS installation ?

In some scenarios you are supposed to install Operating System on the drives connected thru SCSI HBA or SCSI RAID Conrollers,but most of the OS'es will not be updated with drivers for those controllers,that time you need to supply drivers externally,if you are installing windows ,you need to press F6 during the installion of OS and provide the driver disk or CD which came along with HBA.
If you are installing linux you need to type "linux dd" for installing any driver.

9) What is Array ?

Array is a group of Independent physical disks to configure any Volumes or RAID volumes.

10)Can u describe atleast 3 troubleshooting scenarios which you have come across in detail ?

SCENARIO 1:How do you find/debug when there is error while working SCSI devices?

In our daily SAN troubleshooting there are many management and configuration tools we use them to see when there is a failure with target device or initiator device.
Some time it is even hard to trouble shoot some of the things such as media errors in the drives, or some of the drives taking long time to spinnup.In such cases these utilities will not come to help.To debug this kind of information most of the controller will be implemented with 3-pin serial debug port. With serial port debug connector cable you can collect the debug information with hyper terminal software.


SCENARIO 2: I am having an issue with a controller its taking lot of time to boot and detect all the drives connected how can I solve this.?

There are many possibilities that might cause this problem. One of the reason might be you are using bad drives that cannot be repaired . In those cases you replace the disks with working ones.

Another reason might be slots you connected your controller to a slot which might not be supported.
Try to connect with other types of slots.

One more probable reason is if you have flashed the firmware for different OEM’s on the same hardware.
To get rid of this the flash utilities will be having option to erase all the previous and EEPROM and boot block entry option. Use that option to rectify the problem.

SCENARIO 3: I am using tape drive series 700X , even the vendor information on the Tape drive says 700X, but the POST information while booting the server is showing as 500X what could be the problem?

First you should make sure your hardware is of which series , you can find out this in the product website.
Generally you can see this because in most of the testing companies they use same hardware to test different series of same hardware type. What they do is they flash the different series firmware. You can always flash back to exact hardware type.

VIDEO SECTION :
Thanks to Sun Microsystems - SunFire X4600 4-16 Way AMD Server Demo


This blog is updated daily so find more tutorials on Storage Area Networking or SAN

Storage Resume or System Administration Resume

1.What is SAN ?
2.What are the JOB opportunities in SAN ?
3.Which are the companies in SAN and How much they pay ?
4.How Can I Enter SAN industry ?
5.What are the tasks of a SAN professional- How will be a day in his office life?
6.How will be a SAN job interview ?
7.SAN or Storage engineer position - Interview questions : Series1
8.Real SAN Interview questions with answers: Series2
9.Answers for SAN interview questions Series1.
10.Tell me about some Job Openings in SAN or Storage industry?
11.Do You Want to see an Enterprise SAN infrastructure - Thanks to Dell - Watch this informative Video - See a High End Lab