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Three questions

Posted on 2010-11-30
Medium Priority
Last Modified: 2012-05-10
I went to an interview today  they asked

1) How do we configure Raid5
2)What is the main difference between Raid 5 and Raid6 apart from having performance and fault tolerance and no of parities
3)what are the two parities in Raid 6

Could some one explain above questions....Is there and calculation required for configuring raid


Question by:faraz81116
  • 2

Expert Comment

ID: 34238248


First install WIN2003 without the hardware controller installed. Once the OS is up and the domain is setup, install the hardware controller. Go to disk management and config the remaining HD's as dynamic. Use your manual for configing the hardware raid controller on the 3 remaining disks. I recommend getting another HD and creating a mirror of your OS, as it can't reside on the raid 5 volume and you should have a backup of the OS to keep the server up. I would run backups of the OS onto the raid 5 block just in case you get hit with a virus.

Hope that helps.




As a rule, you’ll need one extra drive (for parity): if you have 146GB SCSI drives and need about 500GB of drive space, you’ll need 5 drives (4×146= 584 + one parity drive = 5 drives)
Make sure the drives are identical (not an absolute requirement, but it sure makes life easier…)
Make sure the the drive FIRMWARE IS AT THE SAME REV. LEVEL. this point IS important. You stand a much higher probability of seeing good drives drop off the array (NOT a good situation) with mismatched firmware.
have at least one drive available as a spare.
If the server or array enclosure is in a populated area (i.e.: not in a server room), turn off the alarm (a suggestion only… those of you who have had the pleasure of experiencing the scream of a RAID contoller with a failed drive will understand).
Decide whether you need more spindles or larger drives, and what your default block size will be. This is an area which many admins don’t consider but can seriously impact the performance of an array in any given role if done incorrectly. As a rule (general…), you want more spindles / smaller capacity drives for a database environment as opposed to fewer drives of a larger capacity for file & print or e-mail…




















LVL 47

Expert Comment

ID: 34238899
this is for an interview?  presumably for a sysadmin job?

then you are not going to obtain the skills you need to impress an interviewer by having somebody answer 3 questions for you.  I assure you that there will be 3 more questions on the next interview that will eliminate your chances of getting hired.

these are basic questions that show you don't understand even the fundamentals.

I suggest you spend a day or so reading implementation and configuration guides from hp smartarray , lsi matrix, emc, and lsi raid controllers.  

then also look at raid recovery software and how it works to teach you what can and does go wrong and how to fix it.  just knowing how to configure is the easy part.  if you don't know what can break & how to deal with it, then you still won't get hired. (you just didn't make the cut for the interviewer to get to those questions)

Author Comment

ID: 34239561
Actually these were only three questions among the other questions i was not able to give the satisfactory answers
However your guidance is most appreciated and suggested me some more links which can give me some more fundamental understanding of above mentioned three areas
LVL 47

Accepted Solution

David earned 2000 total points
ID: 34239701
Thx - hope you didn't take it the wrong way. I was conveying that this sort of thing just can't be picked up by being able to answer a few questions.

It reminds me of what a friend of mine told me about medical school.  Year one you learn how the human body works.  Year two you learn how it breaks.  Year three, you learn how to fix it.   Same thing applies here.   Your question was year one stuff ... definitions, and how it worked.

By going to web sites and looking for software that discusses the management, you get to year two.   Then to get to the year three stuff, go to a site that sells "raid recovery software", like runtime.org, and then you'll learn enough to get a full understanding of the technology.  

By knowing how RAID breaks and all the thinks that can go wrong, and how to fix it, or at least what has to be done to fix it, you'll not only have a deeper understanding, but it will influence your decisions on how to build/deploy it in the first place.

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