A customer is planning on migrating their Exchange data to a VNX array. You have gathered the
following information:
6000 IOPS; 50% read/write ratio
Calculating for RAID 5, what is the minimum number of 15K SAS drives required?
A.
84
B.
100
C.
34
D.
96
Why is it 84?
15K SAS – 180 IOPs each
6000/180 = 33.33 ~ 34 Disks!
That’s the minimum. Unless someone gives me another calculation.
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Raid 5 write panalty
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Hello Ice_Man
Here is the correct calculation to do
We Have a Ratio of 50% for Read/Write meaning that
Read IOPS = 6000/2= 3000 IOPS
For write the penalities for Raid 5 is 4 IOPS (2 Reads + 2 Writes)
Write = 6000*4/2=12000
The sum is 12000+3000=15000 IOPS and the required Disks 15K SAS are 15000/180 = 83.33 ~ 84 Disks
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