Missing free space from new raidz2 zpool

[Pekka Järvinen]

I installed FreeBSD-10.2-STABLE-amd64-20150917-r287929-memstick.img and it
gives 28.1T free. So possibly a bug in FreeBSD 10.2-RELEASE-p2 #0 r287260M.

I created bug report
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203330

I also tried with OpenIndiana's ZFS implementation with same machine and it
gives 28.5T free and lists drives as 8001.49GB.


2015-09-26 6:52 GMT+03:00 Peter Jeremy <peter at rulingia.com>:

> On 2015-Sep-24 19:36:50 +0300, Pekka Järvinen <pekka.jarvinen at gmail.com>
> wrote:
> >I bought 6 new 8 TB drives and created new raidz2 pool with these drives.
> >
> >My question is why zfs list and df is only showing 14.5T free? Shouldn't
> it
> >be more close to 30T? Or is that old zfs metadata somehow lurking around
> >and zfs is reading that? Bug?
>
> Your pool seems to be sized correctly but the filesystem can't see all
> the space.  If you're concerned about old metadata, destroy your new
> pool and then dd zeroes over the first and last few MB of each drive -
> which is where ZFS stores its metadata:
>
> for i in /dev/ada{0,1,2,3,4,5};do
>   dd if=/dev/zero of=$i bs=64k count=32
>   dd if=/dev/zero of=$i bs=64k oseek=122094000
> done
>
> ># zpool iostat storage2
> >               capacity     operations    bandwidth
> >pool        alloc   free   read  write   read  write
> >----------  -----  -----  -----  -----  -----  -----
> >storage2     900K  43.5T      0      1      0  7.84K
>
> The 43.5T looks correct.  "zpool list" would be a better command.
>
> ># zdb storage2
> >
> >Cached configuration:
> ...
> >                asize: 48009350479872
> ...
> >MOS Configuration:
> ...
> >                asize: 48009350479872
>
> That's also correct.
>
> As an experiment, I simulated your configuration:
> # cd /tmp
> # mkdir zfs
> # cd zfs
> # for i in 0 1 2 3 4 5;do truncate -s 7814026584k d$i;done
> # zpool create storage2 raidz2 /tmp/zfs/d?
> # zpool list storage2
> NAME       SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH
> ALTROOT
> storage2  43.5T   165K  43.5T         -     0%     0%  1.00x  ONLINE  -
> # zfs list storage2
> NAME       USED  AVAIL  REFER  MOUNTPOINT
> storage2  88.9K  28.1T  32.0K  /storage2
> # zfs get all storage2
> NAME      PROPERTY              VALUE                  SOURCE
> storage2  type                  filesystem             -
> storage2  creation              Sat Sep 26 13:31 2015  -
> storage2  used                  88.9K                  -
> storage2  available             28.1T                  -
> storage2  referenced            32.0K                  -
> storage2  compressratio         1.00x                  -
> storage2  mounted               yes                    -
> ...
>
> --
> Peter Jeremy
>



-- 
Pekka Järvinen