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If we consider, hypothetically, that a server farm is being designed to have 100TB of storage using solid state drives (SSD), each with 250GB each.

My question is how many SSD are needed to ensure redundancy by:

i) RAID 1

ii) RAID 3

iii) RAID 5

What and why is the best choice?

Note that this is an hypothetically question in order to better understand RAID.

Francisco Maria Calisto
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2 Answers2

3

NONE of those options are valid, you can do it in two ways;

  • RAID 10 - you'll need 80 SSDs of that size to give you 100TB, though that doesn't include the typical overhead you'd see so I'd personally go for 90-100.

  • RAID 60 - you'll need 44 SSDs of that size to give you 100TB, this is via 2 x 20+2 R6 arrays, again I'd actually increase this to 50-60 to deal with overhead.

You'd also want at least two disks to act as hot-standby.

This is actually really easy to do by the way, just make sure you get a good disk controller and matching shelves.

Chopper3
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1

For RAID 1 you will get half of the total data size of all drives so you would need 800 drives to get 100TB

RAID 5 will give you all the data minus 1 drive so 401 would be needed.

I believe RAID 3 would require the same 401 drives

Brian
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