A department within an organization requires 200 GB of storage for their business application. The production LUN is RAID 1+0 protected and has a local and remote replica. The local replica is on a RAID 1 LUN and the remote replica is on a five-disk RAID 5 LUN.
If the cost per GB of storage is $2.00, what is the chargeback cost to the department for application storage?
A.
$1050
B.
$1500
C.
$2100
D.
$2900
How this answer was derived, could anyone help ?
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There are three LUNs. The production LUN is RAID 1+0, so 400 GB to get 200 GB.
The local replica is RAID 1. 400 GB to get 200 GB.
The remote replica is RAID 5. 250 GB to get 200 GB.
400 + 400 + 250 = 1050 GB. $2/GB * 1050 GB = $2,100
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Thank you so much for explanation.
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How was the remote replica derived or calculated? 250GB to to 200GB? Can someone please explain this?
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Five-disk RAID 5 needs 1 disk for parity.
So:
X*(5-1) = 200
Where X is 50 -> total storage is 250 GB
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Thank you so much for explanation.
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Thanks Mr. Johnny.
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Although I understand the logic, I hate this question because it is not applicable to the real world. It is assuming that all disks are the same 200GB size. It also doesn’t take into account overhead i.e. if a disk is 200GB, you’re only getting ~180GB usable.
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In facts, in real life, you would chargeback a service for the exact amount of storage it uses. Therefore, ou don’t count the Hard Disks, but you charge for the LUNs storage used. So this is valid in real life.
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C
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