On Mon, 2010-03-15 at 15:03 -0700, Tonmaus wrote:
> Hi Cindy,
> trying to reproduce this
>
> > For a RAIDZ pool, the zpool list command identifies
> > the "inflated" space
> > for the storage pool, which is the physical available
> > space without an
> > accounting for redundancy overhead.
> >
> > The zfs list command identifies how much actual pool
> > space is available
> > to the file systems.
>
> I am lacking 1 TB on my pool:
>
> u...@filemeister:~$ zpool list daten
> NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT
> daten 10T 3,71T 6,29T 37% 1.00x ONLINE -
> u...@filemeister:~$ zpool status daten
> pool: daten
> state: ONLINE
> scrub: none requested
> config:
>
> NAME STATE READ WRITE CKSUM
> daten ONLINE 0 0 0
> raidz2-0 ONLINE 0 0 0
> c10t2d0 ONLINE 0 0 0
> c10t3d0 ONLINE 0 0 0
> c10t4d0 ONLINE 0 0 0
> c10t5d0 ONLINE 0 0 0
> c10t6d0 ONLINE 0 0 0
> c10t7d0 ONLINE 0 0 0
> c10t8d0 ONLINE 0 0 0
> c10t9d0 ONLINE 0 0 0
> c11t18d0 ONLINE 0 0 0
> c11t19d0 ONLINE 0 0 0
> c11t20d0 ONLINE 0 0 0
> spares
> c11t21d0 AVAIL
>
> errors: No known data errors
> u...@filemeister:~$ zfs list daten
> NAME USED AVAIL REFER MOUNTPOINT
> daten 3,01T 4,98T 110M /daten
>
> I am counting 11 disks 1 TB each in a raidz2 pool. This is 11 TB gross
> capacity, and 9 TB net. Zpool is however stating 10 TB and zfs is stating
> 8TB. The difference between net and gross is correct, but where is the
> capacity from the 11th disk going?
>
> Regards,
>
> Tonmaus
1TB disks aren't a terabyte.
Remember, the storage industry uses powers of 10, not 2. it's
annoying.
For each GB, you lose 7% in actual space computation. For each TB, it's
about 9%. So, your "1TB" of is actually about 931 GB.
'zfs list' is going to report in actual powers-of-2, just like df.
In my case, I have a 12 x 1TB configuration, and zfs list shows:
# zpool list
NAME SIZE USED AVAIL CAP HEALTH ALTROOT
array2540 10.9T 5.46T 5.41T 50% ONLINE -
Likewise:
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
array2540 4.53T 4.34T 80.4M /data
So, here's the math:
1 "storage TB" = 1e12 / (1024^3) = 931 actual GB
931 GB x 12 = 11,172 GB
but, 1TB = 1024 GB
so: 931 GB x 12 / (1024) = 10.9TB.
Quick Math: 1 TB of advertised space = 0.91 TB of real space
1 GB of advertised space = 0.93 GB of real space
--
Erik Trimble
Java System Support
Mailstop: usca22-123
Phone: x17195
Santa Clara, CA
Timezone: US/Pacific (GMT-0800)
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