40TB San - Which Raid

for 40 tb i would go mirrored.

but there is a raid that is a mirrored raid 5

both these options are costly but worth it off cause.

not sure if mirrored raid 5 is popular but if not mirrorred would be the go.

raid 5 is the cheapest as it only allows one drive  extra for protection. there it will run if one drive is corrupt.

So raid 5 with hot spare?

The fastest is Raid 10 but you going to loose a lot of disk space
In raid 50 You going to loose half space
In raid 5 you will lose only space from one drive.

So the question is, how many space you can afford to loose ?
If you going to build raid with 10x 4TB drives and you want a maximum space then go for Raid 5
If you prefer security and speed and you can have a half with your drive capacity then go for Raid 50
If you prefer speed and security and loosing some capacity then go for Raid 10.

If you can spare one drive then use 9 drives and leave one for Hot spare.

I am going with 9x 6tb drives..For raid 5 and hot spare. As long as performance is OK, I'll go that route..

9 drives - one for hot spare = 7x6 = 42GB plus hot spare in Raid 5 but it's not going to be a Hell Speed.

Remember if 2 drives will fail in same time or if one will fail and second in process of rebuilding your whole raid will fail. Raid 5 is not too secure

How many drives would I need for a raid 10? How much better is that performance?

There is free Raid calculator, you can use it to see how much space you'll get in different configuration

http://www.raid-calculator.com/default.aspx

For Raid 10 you need 4 or 8 drives

Consider Raid 6 plus spare. I think it's the best choice but You'll get 36TB only

Why is raid 6 better?

2 disks fail tolerance

Please do not even consider using RAID-5

Since individual disk capacities went over 500GB, RAID-5 is no longer recomended.
This is due to the Increased RISK of a second drive failing while the first is still rebuilding.

RAID-6 or RAID10 are the only recomended RAID levels going forward

For RAID10 you would need 14*6TB to give 42TB of useable capacity

thats 7 * 6TB Mirrors

Which SAN? Pretty hard to advise without knowing that.

Raid 5 is obsolete, raid 10, speed, performance and redundancy

I will be going with raid 6 and dell scv200!

You might want to read this first http://www.zdnet.com/article/why-raid-6-stops-working-in-2019/

I have 2 sans, so I'll be OK.

How does that help?

Cobra25, If experts was able to help you make a choice please close this topic and assign point.

Best solution provided. Author expressed himself "I will be going with raid 6 and dell scv200!"