Interview Questions.

Question 1. What Is Raid?

Answer :

Redundant Array of Independent Drives (or Disks), also referred to as Redundant Array of Inexpensive Drives (or Disks) (RAID) is an crucial term for data storage schemes that divide and/or reflect information among a couple of hard drives. They provide, relying on the scheme, expanded information reliability and/or throughput.
RAID is a manner of storing the same information in extraordinary drives(as a result, redundantly) on multiple tough disks.
Question 2. What Are The Advantages Of Raid?

Answer :

Increased redundancy
Increased facts availability
Higher READ/Write overall performance in some RAID levels
Higher Data throughput
higher reliability
Higher Data Security: Through the usage of redundancy, most RAID degrees offer safety for the statistics stored on the array. This manner that the records at the array can resist even the complete failure of one hard disk (or from time to time extra) without any records loss, and with out requiring any data to be restored from backup. This security    characteristic is a key gain of RAID and probable the factor that drives the introduction of more RAID arrays than some other. All RAID stages offer some degree of records protection, relying on the exact implementation, besides RAID level zero.
Fault Tolerance: RAID implementations that encompass redundancy offer a much more reliable universal storage subsystem than may be accomplished through a unmarried disk. This means there may be a lower hazard of the garage subsystem as an entire failing because of hardware disasters. (At the identical time though, the delivered hardware used in RAID means the chances of having a hardware problem of some type with an person aspect, although it would not take down the storage subsystem, is expanded; see this complete dialogue of RAID reliability for more.)
Improved Availability: Availability refers to get right of entry to to information. Good RAID systems enhance availability each with the aid of presenting fault tolerance and by supplying unique capabilities that allow for recovery from hardware faults with out disruption. See the discussion of RAID reliability and also this discussion of superior RAID capabilities.
Increased, Integrated Capacity: By turning a number of smaller drives into a larger array, you upload their capacity collectively (even though a percentage of overall capacity is misplaced to overhead or redundancy in most implementations). This enables applications that require large amounts of contiguous disk space, and additionally makes disk area control easier. Let's assume you need 300 GB of area for a big database. Unfortunately, no difficult disk manufacturer makes a power almost that huge. You could positioned five 72 GB drives into the system, but then you definately'd must discover a few manner to break up the database into 5 pieces, and you would be caught with looking to recall what was had been. Instead, you can installation a RAID 0 array containing those five seventy two GB tough disks; this may seem to the working device as a single, 360 GB hard disk! All RAID implementations offer this "combining" advantage, though the ones that include redundancy of path "waste" some of the gap on that redundant data.
Improved Performance: Last, however surely not least, RAID systems enhance overall performance by using permitting the controller to exploit the talents of more than one difficult disks to get round overall performance-limiting mechanical issues that plague man or woman tough disks. Different RAID implementations enhance overall performance in special approaches and to distinctive ranges, but all enhance it in some way. See this complete discussion of RAID overall performance problems for more.

Active Directory Interview Questions
Question three. What Are Different Levels Of Raid?

Answer :

There are many degrees like

RAID 0,RAID 1,RAID 2,RAID 3,RAID four,RAID 5,RAID 10,RAID 01,RAID 50,RAID 6

But famous are RAID 0,RAID 1,RAID five,RAID 10,RAID 01,RAID 50,RAID 6

commonly used are R0,R1,R5

Question 4. Explain Raid zero, Raid 1, Raid five ?

Answer :

RAID zero:

The lowest designated level of RAID, degree zero, is surely now not a legitimate form of RAID. It changed into given the designation of stage 0 because it fails to provide any stage of redundancy for the information saved in the array. Thus, if one of the drives fails, all of the statistics is damaged.
RAID 0 makes use of a method called striping. Striping takes a single chunk of facts like a picture photo, and spreads that facts across a couple of drives. The benefit that striping has is in stepped forward performance. Twice the quantity of records can be written in a given time frame to the two drives in comparison to that same information being written to a single pressure.
RAID 1:

RAID model 1 changed into the primary real implementation of RAID. It gives a easy form of redundancy for records through a manner referred to as mirroring. This shape typically requires two person drives of similar ability. One power is the energetic power and the secondary pressure is the reflect. When information is written to the lively power, the same statistics is written to the replicate drive.

RAID five:

This is the most effective shape of RAID that can be discovered in a computing device pc device. Typically it requires the form of a hardware controller card to manage the array, but some computing device operating structures can create these through software. This approach uses a shape of striping with parity to hold records redundancy. A minimum of 3 drives is needed to construct a RAID five array and they ought to be equal drives for the satisfactory performance.

Question 5. Whats The Difference Between Raid0 & Raid1 ?

Answer :

RAID 0+1: This is a hybrid shape of RAID that a few producers have applied to try to provide the blessings of each of the 2 versions mixed. Typically this can most effective be carried out on a system with at the least 4 tough drives. It then combines the strategies of mirroring and striping to offer the performance and redundancy. The first set of drives could be active and have the data striped throughout them even as the second one set of drives could be a replicate of the information on the primary two.

RAID 10 or 1+zero: RAID 10 is efficaciously a comparable model to RAID zero+1. Rather than striping facts among the disk units after which mirroring them, the primary  drives within the set are a mirrored collectively. The 2nd two drives form another set of disks this is are reflect of one another but shop striped facts with the primary pair. This is a shape of nested RAID setup. Drives 1 and a pair of are a RAID 1 replicate and drives three and four also are a replicate. These two units are then setup as stripped array.

Hardware and Networking Interview Questions
Question 6. Whats The Difference Between Raid1 And Raid5 ?

Answer :

RAID 1: Minimum 2 drives are required . Gives most effective 50% disk space.

RAID 5: Minimum 3 drives are required . Gives handiest (n-1)X Capacity where n is the no. Of disks, disk space.

Question 7. Whats The Difference Between Raid three & Raid five ?

Answer :

RAID three and RAID 4: Striped Set (3 disk minimal) with Dedicated Parity, the parity bits represent a reminiscence place each, they have a cost of 0 or 1, whether the given memory region is empty or complete, hence improving the velocity of read and write. : Provides advanced overall performance and fault tolerance just like RAID 5, but with a devoted parity disk in preference to rotated parity stripes. The single disk is a bottle-neck for writing due to the fact each write requires updating the parity statistics. One minor benefit is the dedicated parity disk permits the parity force to fail and operation will maintain with out parity or performance penalty.

RAID five does no longer have a committed parity pressure however the parity is turned around across all of the drives subsequently the parity is sent.

RAID 5: Striped Set (three disk minimal) with Distributed Parity: Distributed parity requires all but one drive to be present to function; drive failure calls for alternative, however the array isn't destroyed by using a unmarried pressure failure. Upon pressure failure, any next reads can be calculated from the distributed parity such that the force failure is masked from the stop user. The array can have facts loss inside the event of a 2d force failure and is susceptible until the information that was on the failed force is rebuilt onto a substitute drive.

Red Hat Linux System Administration Interview Questions
Question eight. Whats The Difference Between Raid01 & Raid10?

Answer :

RAID 0+1: Striped Set + Mirrored Set (4 disk minimum; Even quantity of disks) offers fault tolerance and advanced overall performance but will increase complexity. Array maintains to function with one failed power. The key distinction from RAID 1+zero is that RAID zero+1 creates a 2nd striped set to mirror a number one striped set, and as a end result can simplest preserve a maximum of a single disk loss, whereas 1+zero can sustain a couple of pressure losses as long as no two pressure loss contain a unmarried pair.

RAID 1+0: Mirrored Set + Striped Set (four disk minimal; Even number of disks) presents fault tolerance and stepped forward overall performance but increases complexity. Array continues to perform with one or greater failed drives. The key distinction from RAID zero+1 is that RAID 1+zero creates a striped set from a chain of mirrored drives.

Question 9. How Many Minimum Disk Drives Are Needed For R0,r1,r5,r10,r01 ?

Answer :

R0: Minimum 1
R1: Minimum 2
R5: Minimum 3
R10: Minimum 4
R01: Minimum four
DHCP Interview Questions
Question 10. How Raid 5 Works And How Parity Is Calculated ?

Answer :

The parity calculation is normally finished the use of a logical operation known as "different OR" or "XOR". As you may recognise, the "OR" logical operator is "authentic" (1) if either of its operands is authentic, and false (zero) if neither is authentic. The unique OR operator is "real" if and best if certainly one of its operands is authentic; it differs from "OR" in that if both operands are genuine, "XOR" is false.

Question eleven. Other Than Raid Feature What Are The Other Features In Software Management Functionalities?

Answer :

Hot spare
Raid degree migration (RLM)
SNMP interplay/control
SCCM Interview Questions
Question 12. What Is Initialization?

Answer :

Initialization is the manner of preparing a drive for garage use. It erases all statistics at the power & makes way for brand spanking new record gadget creation.

Active Directory Interview Questions
Question thirteen. What Is Check Consistency?

Answer :

Consistency take a look at or CC verifies correctness of statistics in logical drives. This is a function of some of the RAID hardware controller cards.

Question 14. What Is Background Initialization?

Answer :

This is a Consistency take a look at manner forced while a new logical power is created. This is an automatic operation that begins 5 mins after the new logical pressure is created.

Question 15. What Is A Raid Array ?

Answer :

RAID array is a group of disks which can be configured with RAID. That manner they're in a redundant setup to tolerate any disk failures.

Netapps Interview Questions
Question 16. Whats The Difference Between A Jbod & A Raid Array ?

Answer :

Just A Bunch Of Disks (JBOD):-

Hard disks that aren't configured in a RAID configuration. They are just disks piled or connected in a single unmarried enclosure.
RAID is having the benefit of bearing a disk failure & nonetheless provide records availability.
Question 17. When Jbod Is Preferred Over Raid Array ?

Answer :

When there's no need for redundancy & when it's far adequate if there is some hard disk failure or facts unavailability in such eventualities JBOD is prefered over RAID due to the fact JBOD is cheaper storage answer. It is likewise clean to setup & begin the usage of as compared to RAID.

Storage Area Network Interview Questions
Question 18. What Is A Hot Spare?

Answer :

Hot spare is an additional, unused disk drive that is a part of the disk subsystem. It is commonly in standby mode geared up for carrier if a force fails. Whenever there's a power failure this warm spare kicks in & takes over that failed force's role.

Hardware and Networking Interview Questions
Question 19. What Is A Logical Drive Or Virtual Drive ?

Answer :

The partitioning or department of a huge hard force into smaller gadgets. A single, massive Physical Drive can be partitioned into two or greater smaller Logical Drives.

Question 20. What Is Rebuilding Of Array ?

Answer :

Whenever there is a disk failure in the RAID array the array goes to DOWNGRADED STATE. SO whilst we plug out the failed force & insert a new functioning pressure the RAID configured array begins regenerating the information to the more moderen drive. This procedure is known as rebuilding.

Windows Server Support Interview Questions
Question 21. What You Do When A Drive In An Array Fails, How You Bring It Back To Optimal Online Mode?

Answer :

We switch out failed power & plugin new functioning force & watch for the rebuilding manner to complete. We make certain rebuild system happens with none errors. Once that completes array is again to most excellent on-line kingdom.

Question 22. What Are The Different States An Array Can Be In And Explain Each State?

Answer :

Online
Downgraded
Offline
Rebuilding
Question 23. Explain Online,offline,degraded States Of An Array ?

Answer :

Online:- while all drives are running exceptional

Downgraded:- Whenever there is a pressure failure but nevertheless the array is functioning first-rate

Offline:- Array or entire facts storage is down

Rebuilding:- Storage access is there however for the reason that a new pressure has been inserted in place of a failed pressure statistics is being written to new power which may sluggish down the overall performance of the entire RAID array.

IPTABLES Interview Questions
Question 24. What Is The Difference Between A Global Hot Spare & A Dedicated Hot Spare ?

Answer :

Global hotplate is available for the any  array within the whole enclosure or Storage subsystem.
If there's an enclosure having 10 drives & we have 3 drives in RAID5(1st array) , three greater drives in 2nd RAID5(second array) & 2 more drives in RAID 1 config. We can specify in RAID config application whether a committed hot spare is assigned for 1st RAID5 array. If there may be a drive failure in 2d or 3rd array this devoted warm spare will no longer be concerned there. But if the array for which this is devoted has any pressure failure this devoted hot spare takes over.
Red Hat Linux System Administration Interview Questions
Question 25. How Raid Is Configured Through Bios ?

Answer :

If we've a Hardware RAID controller card it gives an alternative even as machine booting to go into into RAID BIOS software. Here we've got alternatives which give us alternatives to create RAID the use of a semi-GUI(DOS based totally GUI) interface.

Question 26. How Raid Is Configured In Os Level?

Answer :

Once we installation device drivers & additionally RAID config or control application using that we will configure RAID in OS level.

Yum Interview Questions
Question 27. What Is The Difference Between A Software Raid & Hardware Raid ?

Answer :

In order for RAID to characteristic, there needs to be software program both via the running device or thru devoted hardware to correctly take care of the go with the flow of facts from the pc system to the force array. This is in particular crucial in terms of RAID 5 because of the huge amount of computing required to generate the parity calculations.
In the case of software implementations, CPU cycles are taken away from the overall computing surroundings to perform the essential obligations for the RAID interface. Software implementations are very low price monetarily because all this is vital to put in force one is the difficult drives. The problem with software program RAID implementations is the overall performance drop of the machine. In popular, this performance hit can be anywhere from 5% or even more relying upon the processor, reminiscence, drives used and the level of RAID implemented. Most humans do no longer use software program RAID anymore due to the reducing prices of hardware RAID controllers over the years.
Hardware RAID has the advantage of devoted circuitry to handle all the RAID power array calculations outdoor of the processor. This presents wonderful overall performance for the storage array. The drawbacks to hardware RAID have been the costs. In the case of RAID 0/1 controllers, the ones prices have emerge as so low that many chipset and motherboard producers are which includes these abilities at the motherboards. The real expenses rest with RAID 5 hardware that require more circuitry for added computing ability.
DHCP Interview Questions
Question 28. Which Is Best Raid Level For Performance And Which Is Best For Redundancy?

Answer :

RAID 0 for overall performance

RAID 5 or RAID 6 better for redundancy(availability)