a (hopefully) simple newbie zfs query regarding available space

[John .]

2009/8/9 chris scott <kraduk at googlemail.com>:

>
> not a zfs thing is happens with all os and file systems. Basically HD
> manufacturers quote their capacities in base 10 ie 1 TB = 1000000000 bytes.
> File systems are calculated in binary therefore the calculation they use is
> 1024 x 1024 x 1024 = 1099511627776. Slightly more as you can see.
>
> Therefore 1 GB is os terms is 1073741824
>
> therefore hd capacity in GB is
>
> 1000000000000/1073741824 = 931.322575
>
> The extra you see is it due to HD manufactures slightly over capacity the
> drives
>

Hi,

What I meant was, I was seeing 931MB instead of 1.6TB (2x1TB disks)
but this was because I didn't read about zfs properly (they recommend
3 or more disks. In the man page for zpool it says:

"A  raidz group with N disks of size X with P parity disks can hold
approximately (N-P)*X bytes
[...]
The recommended number is between 3 and 9"

so, I'll wait till I get an array before implementing zfs. In the
meantime, I'm using gconcat. Sorry for the noise.

-- 
John