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Is the usable size of a RAIDZ array similar to the usable size of a RAID5 array?

The RAID5 calculation is "(N-1) * S", where S is the size of smallest drive. Since most people use the same sized disk in a RAID5 array, this comes out to be "N-1" for most purposes.

Is RAIDZ also "(N-1) * Smin" ?

Similarly, RAID6 is (N-2) * S. Is the usable size of RAIDZ2 similar to RAID6?

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2 Answers 2

up vote 5 down vote accepted

for RAIDZ(1) use the same formula as for RAID5. for RAIDZ2 - the same as for RAID6

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To complement the accepted answer, a calculator:

Raid Calculator | Raid Disk Space Utilization Calculator | ServeTheHome

RAID5 uses one disk for Parity and requires at least three drives to be used.

RAID-Z uses one disk for Parity much like RAID5 and requires at least three drives to be used.

RAID-Z2 uses two disks for Parity and requires at least four drives to be used.

… 

RAID-Z3 uses three disks for Parity and requires at least five drives to be used.

… and so on.

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