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Dynamic disk pool VS Raid 6

Hi Experts,

I got new MD3640 with 20 physical disks 4TB for each , I tried to created RAID 6 and got the total usable space 65 TB but with dynamic pool i got just 52 TB , why this difference ?

Also what is the best to use RAID 6 or Dynamic Disk pool if i intend to make this MD host FTP files , Web Server files and storage server .

Thanks in advance

Member_2_231077

You haven't taken into account that DDP has distributed hot spares, so that takes up extra space. Your RAID 6 hasn't got any hot spares. There doesn't seem to be an accurate description of the algorithms used though.

Since NetApp bought the Engenio OEM business from LSI they've probably put some of their intellectual property from the standard NetApp filers into it, so there's likely to be WAFL/RAID-Z or something like it.

http://www.netapp.com/uk/system/pdf-reader.aspx?cc=uk&m=ds-3309.pdf&pdfUri=tcm:42-59797

http://storageviews.com/ (March 8th, 2014 section) has a bit more on one of the algorithms, looks reasonable.

Mohamed Hammad

ASKER

Thanks andyalder ,

I knew that DDP reserve two HDD and give me total usable space 51 TB with RAID 6 i reserve two hot spare but it also give me 58 TB still 7 TB difference .

also what is the best for production use DDP or RAID 6

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Member_2_231077

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