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Raid Question

By drmweaver ·
I'm looking at buying a snap server with 4 120 Gig drives for a total of 480 gigs. This is Raid 5 striping and parity and raid 1 mirroring.

Question, since this is a raid 5, would the total size change or would there actually be 480 gigs of available space?

Thanks. Just trying to understand how this raid stuff works.

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Some capacity is used for data recovery

by stress junkie In reply to Raid Question

RAID 5 works by writing some data recovery information to the disks. This results in less capacity for user data than the sum of the capacities of the disks in the RAID5 array. I hope this helps. You can obtain more information about RAID by using a Google search for RAID 5.

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RAID 5

by tmcavan In reply to Raid Question

One of the drives would be used for recovery, you would have what appears to be 360 gigs space available

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I believe that's RAID 4

by stress junkie In reply to RAID 5

A three drive RAID 4 array uses one disk for data recovery/redundancy information. The other two disks contain user data. So the user data capacity of RAID 4 is the sum of two of the three disks.

A three drive RAID 5 array distributes the recovery/redundancy information over all three drives. It also distributes the user data over all three drives. I believe that the user data capacity is better on a RAID 5 configuration than on RAID4.

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You lose some...

by Hockeyist In reply to Raid Question

...in my experience you will lose approximately 1 drive's capacity to fault tolerance in the average raid 5 array.
Check out this link for a good description of raid fundamentals.
http://www.adaptec.com/worldwide/common/editorial.html?sess=no&prodkey=linux_wp

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