4 x 2TB Disks added to HP Proliant Gen8 - Smart array showing 4TB space available after Raid5?!

hi guys

We have an Hp Proliant with a total of 11 bays. So we merely added 4 x 2TB disks to the available bays. When I log onto the smart array and I try to create a logical drive, it only says I will have 3.2TB of space! That's crazy.

With a Raid 5 config, I would have thought the finished space would end up being 6TB's.

Any ideas guys?

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YashyAuthor Commented:
Basically if I go to create a new logical drive in order to have these new disks added, the maximum space is only 3.2TB i total. With 4 x 2TB = 8TB. If you Raid 5 that, it should total to around 6TB's, not 3.2TB?
David Johnson, CD, MVPOwnerCommented:
try 63 sectors/track and use custom size
I strongly recommend against the use of RAID 5, as it is a very unreliable form of RAID and not necessary with today's very large disks. Particularly if you have to do a rebuild, with such large disks it will take ages to complete during which time you have the risk of further failures which can kill the data on the array. Use RAID 6 instead, that is far much more reliable and makes more sense.
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YashyAuthor Commented:
Okay guys, so the issue is this: the 2TB disks have been added to an array which has had 1TB disks!!! So the data has been evenly distributed, but seeing as the 1TB disks were the size of each disk on the array, the maximum size on the 2TB has now turned into 1TB!!

What would happen if I now go and erase those four 2TB disks in order to go back to the beginning and instead create a brand new array, just for these four disks? Is this possible?
It depends on the RAID controller, most of them only allow you to extend arrays, and not to reduce them. So you'll probably be best off to make a backup, kill the array, and then build 2 new ones. This time you can do it properly from the beginning and use RAID 6 for both of your arrays. After that just restore from your backup.
andyalderSaggar maker's framemakerCommented:
You can remove drives from an array but you need to buy and install the Smart Array Advanced Pack license for that to be enabled.
YashyAuthor Commented:
Andy, does this mean if we got the Smart Array Advanced Pack, that we would be able to erase those newly added drives without affecting the actual array?

Or does the license pack only benefit by being on site and removing the disk manually from the bay?
andyalderSaggar maker's framemakerCommented:
It allows you to logically remove drives from an array, it's the exact opposite of adding them. It re-stripes the logical disks over the remaining physical disks. It takes as long as expansion so You can then reassign them to another array or make a new one with them. There's a 60 day trial/evaluation available so you don't even have to pay for it.

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YashyAuthor Commented:
Perfect stuff man. Thank you.
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