ZFS filesystem not showing total size?

[xorquewasp]

Hello.

I've got the following hardware setup:

ad10: 76319MB <WDC WD800AAJS-00WAA0 58.01D58> at ata5-master SATA300
ad11: 953869MB <WDC WD1001FALS-00J7B1 05.00K05> at ata5-slave SATA300
ad12: 953869MB <WDC WD10EADS-00L5B1 01.01A01> at ata6-master SATA300
ad14: 476940MB <WDC WD5001AALS-00L3B2 01.03B01> at ata7-master SATA300
ad16: 476940MB <WDC WD5001AALS-00L3B2 01.03B01> at ata8-master SATA300

ad12 is used as a single-disk pool. ad10 is formatted UFS2 for the OS.

I'm attempting to create a RAIDZ pool (with parity) over ad11, ad14
and ad16.

I've performed the following steps:

# zpool create storage raidz ad11 ad14 ad16
# zpool list
NAME                    SIZE    USED   AVAIL    CAP  HEALTH     ALTROOT
backup                  928G    166K    928G     0%  ONLINE     -
storage                1.36T    292K   1.36T     0%  ONLINE     -

# zfs create storage/home
# zfs create storage/home/xw
# zfs set compression=gzip storage/home
# zfs set compression=gzip storage/home/xw

# zfs list
NAME              USED  AVAIL  REFER  MOUNTPOINT
storage           188K   913G  25.3K  /storage
storage/home     49.3K   913G  25.3K  /storage/home
storage/home/xw  24.0K   913G  24.0K  /storage/home/xw

I seem to have less storage than I'd expect. Is there something wrong
with this setup?

xw
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[Artem Belevich]

On Mon, Jun 22, 2009 at 5:31 PM, <xorquewasp@...> wrote:
> ad11: 953869MB <WDC WD1001FALS-00J7B1 05.00K05> at ata5-slave SATA300
..
> ad14: 476940MB <WDC WD5001AALS-00L3B2 01.03B01> at ata7-master SATA300
> ad16: 476940MB <WDC WD5001AALS-00L3B2 01.03B01> at ata8-master SATA300
..
># zpool create storage raidz ad11 ad14 ad16
> I seem to have less storage than I'd expect. Is there something wrong
> with this setup?

You've created raidz pool from 2x500G hard drives and one 1T hard
drive. RAIDZ needs elements of the array to be of the same size, so
you're effectively wasting half of your 1T drive (ad11). Total raw
capacity of the pool is 476G*3 = ~ 1.36T with 2/3of it (913G) usable
for user data -- exactly what zfs shows you.

Obvious fix would be to build the pool from the drives of the same
size. You may try concatenating or striping ad14+ad16 with geom and
create mirrored pool with ad11 -- usable size would be a bit larger
than what you have. Resulting pool should be faster than RAIDZ.

Another option would be to get another 1T drive and build RAIDZ pool
with 2x1T + (striped 2x500G) for a total usable size of ~2T.

I'd advise against splitting 1T drive into two partitions and use them
as two elements of RAIDZ pool -- this would effectively kill
redundancy that RAIDZ is supposed to provide. If your 1T drive dies,
your whole pool would go down with it. Performance would also suck as
1T drive will be constantly seeking.

--Artem
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[xorquewasp]

On 2009-06-22 21:28:26, Artem Belevich wrote:

> On Mon, Jun 22, 2009 at 5:31 PM, <xorquewasp@...> wrote:
> > ad11: 953869MB <WDC WD1001FALS-00J7B1 05.00K05> at ata5-slave SATA300
> ..
> > ad14: 476940MB <WDC WD5001AALS-00L3B2 01.03B01> at ata7-master SATA300
> > ad16: 476940MB <WDC WD5001AALS-00L3B2 01.03B01> at ata8-master SATA300
> ..
> ># zpool create storage raidz ad11 ad14 ad16
> > I seem to have less storage than I'd expect. Is there something wrong
> > with this setup?
>
> You've created raidz pool from 2x500G hard drives and one 1T hard
> drive. RAIDZ needs elements of the array to be of the same size, so
> you're effectively wasting half of your 1T drive (ad11). Total raw
> capacity of the pool is 476G*3 = ~ 1.36T with 2/3of it (913G) usable
> for user data -- exactly what zfs shows you.

Thanks, I was afraid of that.

I'll swap the 1tb disk for a 500gb today. I was only planning to get
1tb of storage but found that I had a spare 1tb disk laying around so
I put that into the array instead.

xw
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[xorquewasp]

On 2009-06-23 17:47:26, Marcus Reid wrote:
> Hi,
>
> As a side note, freebsd-hackers is not the correct list for this question.

I considered it a hackers@ question due to the large "ZFS is an experimental
feature" warning.

xw
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