ZFS disk space

S

Sylhouette

Hello all
I am running 8.0 Current from today and started to use ZFS.

I have 5 250GB disks

I have labeled them using glabel like ad5 = disk01, ad6 = disk02 to disk05

I have created a raidz2 pool named storage.
Code: 
zpool create -f storage raidz2 label/disk01 label/disk02 label/disk03 label/disk04 label/disk05

zpool status give's me the following
Code: 
zpool status
  pool: storage
 state: ONLINE
 scrub: none requested
config:

        NAME              STATE     READ WRITE CKSUM
        storage           ONLINE       0     0     0
          raidz2          ONLINE       0     0     0
            label/disk01  ONLINE       0     0     0
            label/disk02  ONLINE       0     0     0
            label/disk03  ONLINE       0     0     0
            label/disk04  ONLINE       0     0     0
            label/disk05  ONLINE       0     0     0

errors: No known data errors

i created some mountpoints and filesystems on the storage pool

zpool list shows me the following

Code: 
zpool list
NAME      SIZE   USED  AVAIL    CAP  HEALTH  ALTROOT
storage  1.13T   368M  1.13T     0%  ONLINE  -

All looks good.
But when i do a df -h on my system i get a total of 680M for my /storage pool?

Code: 
df -h
Filesystem                 Size    Used   Avail Capacity  Mounted on
/dev/ad4s1a                496M    242M    214M    53%    /
devfs                      1.0K    1.0K      0B   100%    /dev
/dev/ad4s1e                989M     12K    910M     0%    /tmp
/dev/ad4s1f                217G    2.9G    197G     1%    /usr
/dev/ad4s1d                2.8G    844K    2.6G     0%    /var
storage                    680G    128K    680G     0%    /storage
storage/ncvs               680G    128K    680G     0%    /storage/ncvs
storage/www                680G    128K    680G     0%    /usr/local/www
storage/ports              680G    217M    680G     0%    /usr/ports
storage/ports/distfiles    680G    1.3M    680G     0%    /usr/ports/distfiles


zpool list shows me a pool of 1.13T Bytes
as where df gives me a size of 680G Bytes

Now my main question, what is the actual size of the storage pool??

regards,
Johan
 
According to the zpool(1M) man page the space rules for a raidz2 are:

A raidz group with N disks of size X with P parity disks can hold approximately (N-P)*X bytes ...
Click to expand...

So in your case N=5, X=250GB, and P=2 and you get (5-2)*250GB = 750GB. When you factor in filesystem overhead your value of 680GB doesn't seem too unreasonable.
 
5 * 250GB = +/- 1.13TB without accounting for the raidz.
 
zpool list shows you the size of all your disks (5 * 250 GB=~1.2 TB) including parity space.

zfs list shows you the space available to filesystems/volumes, after all the parity is accounted for. With 2 parity disks, you get 3 * 250 GB = ~750 GB. Add in ZFS overhead for redundant metadata and other info, and you get what you see.
 
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