Date: Sun, 9 Aug 2009 10:01:41 +0100 From: "John ." <comp.john@googlemail.com> To: freebsd-questions@freebsd.org Subject: Re: a (hopefully) simple newbie zfs query regarding available space Message-ID: <abc784790908090201m734fd150ue4efe1a1a5e20a89@mail.gmail.com> In-Reply-To: <abc784790908090200j4d4f97e0je437f4977604b606@mail.gmail.com> References: <abc784790908090039j2c7bbc6bsdebf7a2d8faf96c3@mail.gmail.com> <d36406630908090143t5a5023a4j4ac2df37b0782fd7@mail.gmail.com> <abc784790908090200j4d4f97e0je437f4977604b606@mail.gmail.com>
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2009/8/9 chris scott <kraduk@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 =3D 1000000000 by= tes. > File systems are calculated in binary therefore the calculation they use = is > 1024 x 1024 x 1024 =3D 1099511627776. Slightly more as you can see. > > Therefore 1 GB is os terms is 1073741824 > > therefore hd capacity in GB is > > 1000000000000/1073741824 =3D 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 =A0raidz 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. --=20 John
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