SK0-003 · Question #358
A server consists of two 72GB SCSI drives and four 146GB SCSI drives. All drives are attached to a RAID controller. The system administrator has decided to configure all six drives in a RAID 5…
The correct answer is B. 360GB. In a RAID 5 array with drives of different sizes, the usable capacity is determined by the smallest drive's size multiplied by the total number of drives minus one for parity.
Question
A server consists of two 72GB SCSI drives and four 146GB SCSI drives. All drives are attached to a RAID controller. The system administrator has decided to configure all six drives in a RAID 5 array. How much usable disk space will this array have?
Options
- A288GB
- B360GB
- C432GB
- D728GBb
How the community answered
(39 responses)- A21% (8)
- B67% (26)
- C5% (2)
- D8% (3)
Why each option
In a RAID 5 array with drives of different sizes, the usable capacity is determined by the smallest drive's size multiplied by the total number of drives minus one for parity.
This calculation does not correctly account for the number of drives or the parity overhead in a RAID 5 configuration.
For a RAID 5 array configured with mixed-size drives, the effective size of all drives is limited by the smallest drive (72GB). With six drives, one drive's worth of capacity is used for parity, leaving (6 - 1) * 72GB = 5 * 72GB = 360GB of usable disk space.
This calculation incorrectly sums all drive sizes and then subtracts one, which is not how RAID 5 capacity is determined, especially with mixed drive sizes.
This calculation is incorrect for RAID 5 and does not properly account for parity or the effective drive size with mixed capacities.
Concept tested: RAID 5 usable capacity calculation with mixed drive sizes
Source: https://learn.microsoft.com/en-us/windows-server/storage/disk-management/understanding-raid
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