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I just installed NexentaStor Open Source on a Dell R510.

I created a Raid-Z1 with 4 x 2TB disks. No Spare disks configured.

NexentaStor now tells me the the Datasat have 7,35TB free space, I was expecting aboutn 5,5 TB, because of the n-1 rule.

Can anyone tell me why?

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What does zpool status show? Sounds like you created something wrong... – Chris S Feb 8 '13 at 14:44
Can you provide a screenshot of your Data Management -> Data Sets screen in the NexentaStor interface? – ewwhite Feb 8 '13 at 14:56
ewwhite: Here you go. Data Set: Disks: – Jacob Bach Pedersen Feb 11 '13 at 8:25
up vote 3 down vote accepted

Your zpool list will show the RAW space available to the pool (sum of disks).

Your zfs list will show the amount of usable post-RAID redundancy space available.

Of course, du and ls will show different values, too...

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disk manufacturers use base-10 when sizing disks, while computers use base-2. So that 2TB HDD as labeled on the box, is likely to be recognized by your OS as 1.83 TB. 4 * 1.83 = 7.32, which is pretty close. Keep in mind that ZFS doesn't reserve whole disks for parity, instead all the disks are stripes and it's the data for which parity is calculated. – Tim Kennedy Feb 20 '13 at 21:48

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