[OpenIndiana-discuss] Doubt on ZFS

[Jeppe Toustrup]

2011/2/3 Basil Kurian <basilkurian at gmail.com>:
> [root at beastie /etc]# zpool create nas da0 da1
> [root at beastie /etc]# zpool list
> NAME   SIZE   USED  AVAIL    CAP  HEALTH  ALTROOT
> nas   23.9G  73.5K  23.9G     0%  ONLINE  -
> [root at beastie /etc]# zpool add nas da2
> [root at beastie /etc]# zpool list
> NAME   SIZE   USED  AVAIL    CAP  HEALTH  ALTROOT
> nas   35.8G   134K  35.8G     0%  ONLINE  -
>
> *Then I stored one big file on /nas . after that , I tried to remove newly
> attached disk.*
>
> [root at beastie /etc]# du -sh /nas/huge_file
> 464M    /nas/huge_file
> [root at beastie ~]# zpool remove nas da2
> cannot remove da2: only inactive hot spares or cache devices can be removed
> [root at beastie ~]# zpool offline  nas da2
> cannot offline da2: no valid replicas
> [root at beastie ~]# zpool detach  nas da2
> cannot detach da2: only applicable to mirror and replacing vdevs
>
> *
> Though the data stored in the pool is much less that the size of individual
> disks ,  I 'm unable to remove any of the members from the pool. How can I
> do that without losing data ?
> *

You can't, unless it's a mirror. What you created is essentially a RAID 0 setup.


> *I have one more doubt*
>
> [root at beastie ~]# zpool create nas mirror ad4 ad6 mirror da0 da1
> [root at beastie ~]# zpool status
>  pool: nas
>  state: ONLINE
>  scrub: none requested
> config:
>
>    NAME        STATE     READ WRITE CKSUM
>    nas         ONLINE       0     0     0
>      mirror    ONLINE       0     0     0
>        ad4     ONLINE       0     0     0
>        ad6     ONLINE       0     0     0
>      mirror    ONLINE       0     0     0
>        da0     ONLINE       0     0     0
>        da1     ONLINE       0     0     0
>
> [root at beastie ~]# zpool detach nas da0
> [root at beastie ~]# zpool status
>  pool: nas
>  state: ONLINE
>  scrub: none requested
> config:
>
>    NAME        STATE     READ WRITE CKSUM
>    nas         ONLINE       0     0     0
>      mirror    ONLINE       0     0     0
>        ad4     ONLINE       0     0     0
>        ad6     ONLINE       0     0     0
>      da1       ONLINE       0     0     0
>
> errors: No known data errors
>
> [root at beastie ~]# zpool attach nas da0
> missing <new_device> specification
> [root at beastie ~]# zpool attach nas da0 da1
> invalid vdev specification
> use '-f' to override the following errors:
> /dev/da1 is part of active pool 'nas'
>
>
> *How can I reattach it to the pool ?*

Each drive/partition which has been in a ZFS pool, get it's last pool
name, pool UID, etc. written to the drive, this is then checked when
you want to use the drive again. The warning you get is to make sure
you won't overwrite data on the wrong drive.
When you are sure you are trying to add the correct drive, then simply
add the '-f' option, as it tells you to, and the drive will be added
to the pool.


> *Finally one more doubt too*
> [root at beastie ~]# zpool create nas mirror ad4 ad6 mirror da0 da1
>
> *can we do this in two steps. something like*
>
> [root at beastie ~]# zpool create nas1 mirror ad4 ad6
> [root at beastie ~]# zpool create nas2 mirror da0 da1
> [root at beastie ~]# zpool create nas nas1 nas 2
> cannot open 'nas1': no such GEOM provider
> must be a full path or shorthand device name

Sure, but you have to use the 'add' command to add the extra mirror then:

root at Urraco:/# mkfile 100m disk1 disk2 disk3 disk4
root at Urraco:/# zpool create testpool mirror /disk1 /disk2
root at Urraco:/# zpool status testpool
  pool: testpool
 state: ONLINE
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        testpool    ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            /disk1  ONLINE       0     0     0
            /disk2  ONLINE       0     0     0

errors: No known data errors
root at Urraco:/# zpool add testpool mirror /disk3 /disk4
root at Urraco:/# zpool status testpool
  pool: testpool
 state: ONLINE
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        testpool    ONLINE       0     0     0
          mirror-0  ONLINE       0     0     0
            /disk1  ONLINE       0     0     0
            /disk2  ONLINE       0     0     0
          mirror-1  ONLINE       0     0     0
            /disk3  ONLINE       0     0     0
            /disk4  ONLINE       0     0     0

errors: No known data errors


--
Venlig hilsen / Kind regards
Jeppe Toustrup (aka. Tenzer)