Date: Sun, 9 Aug 2009 10:13:10 +0100 From: chris scott <kraduk@googlemail.com> To: "John ." <comp.john@googlemail.com> Cc: freebsd-questions@freebsd.org Subject: Re: a (hopefully) simple newbie zfs query regarding available space Message-ID: <d36406630908090213t14529e65x9e101f5874b0c784@mail.gmail.com> In-Reply-To: <abc784790908090201m734fd150ue4efe1a1a5e20a89@mail.gmail.com> References: <abc784790908090039j2c7bbc6bsdebf7a2d8faf96c3@mail.gmail.com> <d36406630908090143t5a5023a4j4ac2df37b0782fd7@mail.gmail.com> <abc784790908090200j4d4f97e0je437f4977604b606@mail.gmail.com> <abc784790908090201m734fd150ue4efe1a1a5e20a89@mail.gmail.com>
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2009/8/9 John . <comp.john@googlemail.com> > 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 = 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 > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to " > freebsd-questions-unsubscribe@freebsd.org" > ah did you do a zpool create tank ad0 then zpool attach tank ad1 type thing? if you did you have you have created a mirror to fix do a zpool dettach ad1 then a zpool add ad1 to create a stripe Having said that it not good practice to have no redundancy. You could comprise by putting your important data on a dedicated file system then setting copies to 2 or 3
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