Date: Wed, 29 Sep 2010 11:14:26 +0100 From: krad <kraduk@gmail.com> To: =?ISO-8859-1?Q?Morgan_Wesstr=F6m?= <freebsd-questions@pp.dyndns.biz> Cc: freebsd-questions@freebsd.org, Aaron <drizzt321@gmail.com> Subject: Re: Disappearing available space with ZFS...what am I missing? Message-ID: <AANLkTinN0dDZve0Dk3S6CTAkAwa_G3jqPzhedO%2BRRTVq@mail.gmail.com> In-Reply-To: <4CA302E5.9050004@pp.dyndns.biz> References: <AANLkTinRWacA8%2BYjy91S_P==o2QZbc4nmqweXiEyHm9L@mail.gmail.com> <4CA302E5.9050004@pp.dyndns.biz>
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On 29 September 2010 10:12, Morgan Wesstr=F6m <freebsd-questions@pp.dyndns.= biz > wrote: > On 2010-09-29 07:56, Aaron wrote: > >> I've created a ZFS pool with zpool create tank raidz ada0 ada1 ada2 >> ada3, and then I add some additional mountpoints (I think they're >> called) using zfs create tank/storage, etc. In zpool list, I see the >> pool with 3.62T available. With df -h, I see 2.4T available for tank, >> and tank/storage. When I first created tank, it had the 3.62T >> available as I expected. What am I missing? I do have compression set >> to gzip-9 on tank which gets inherited like I want, don't know if that >> would affect anything. >> >> --Aaron >> > > There's nothing wrong here that I can see, you just have to make a > distinction between the zfs pool and the filesystems within the pool and = I > agree it can be confusing at first. > > The numbers suggest you are using 4 x 1TB (base 10 TB) drives? That equal= s > 3.7TiB (base 2 TB) which is the unit zpool/zfs uses. This is the total > amount of space available to the pool and includes all space on all drive= s > in the pool. Nothing strange so far. > > Now, since you've told zpool to create filesystems within the pool using > raidz, the filesystems will have 25% less space available since this spac= e > is used for parity data. So a filesystem using the whole pool will report > having 3.7 * 0.75 =3D 2.7TiB available which is in agreement with your > numbers. A raidz filesystem will always lose 1 disk worth of space and wi= ll > never report that space as available to you since it will always be occup= ied > with parity data. > > The pool on the other hand doesn't make a distinction, in this case anywa= y, > between user data and parity data so zpool will always report what's > actually unallocated on all your physical drives in the pool. For every G= iB > you allocate in the filesystem you will allocate 1.33GiB in the pool sinc= e > that includes parity data. "zfs list" and "df -h" are your best friends t= o > find out how much space is available for your files. Don't bother about > "zpool list". > > Regards > Morgan > > _______________________________________________ > 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" > It gets even more hairy when you start adding in reservsions, quotas, and compression. Slap dedup on top of that and you get magically growing fs according to df 8)
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