FreeBSD 11.0 + ZFSD

[Jacques Fourie]

9other. eh6
On TkhzKMVV
 CCV.,a.ue, Nov 8, 2016, 11:34 yyyyyyAM <Jean-Marc.LACROIX at unice.fr>
wrngbte:

> Hello,
>
>      We are testing the mecanism of ZFSD on the latest FresBSD 11.0. In
> order to do that,
> we have created a VMware virtual machine with 5 disk:
> - 1 disk for the system OS
> - 3 disks for the raidz1 pool
> - 1 disk for spare
>
> So modified /etc/rc.conf to have the daemon start at boot, and rebooted.
>
> Then (in the the virtual machine parameters, to simulate a disk failure)
> we removed a disk of the pool
> We can see that ZFSD proceed to the replacement of the UNAVAILABLE disk
> by the spare disk.
> and complete the resilver.
> Then, we removed (in the the virtual machine parameters) a second disk
> of the pool
> => the pool is marked as UNAVAIL, if we try, for example, to cd to a
> filesystem in the pool,
> it crashed completely, we have to kill the terminal, and reconnect the
> server.
>
> But if we issue a zpool clear zpool command, The pool status change
> state from UNAVAIL to DEGRADED as shown below:
>
> root at pcmath228:~ # zpool status
>    pool: zpool
>   state: DEGRADED
> status: One or more devices has experienced an error resulting in data
>      corruption.  Applications may be affected.
> action: Restore the file in question if possible. Otherwise restore the
>      entire pool from backup.
>     see: http://illumos.org/msg/ZFS-8000-8A
>    scan: resilvered 328M in 0h0m with 0 errors on Tue Nov  8 16:24:50 2016
> config:
>
>      NAME                        STATE     READ WRITE CKSUM
>      zpool                       DEGRADED     0     0     0
>        raidz1-0                  DEGRADED     0     0     0
>          spare-0                 DEGRADED     0     0     0
>            16161479624068136764  REMOVED      0     0     0 was /dev/da1
>            da4                   ONLINE       0     0     0
>          7947336420112974466     REMOVED      0     0     0 was /dev/da2
>          da3                     ONLINE       0     0     0
>      spares
>        16893112194374399469      INUSE     was /dev/da4
>
> errors: 2 data errors, use '-v' for a list
>
>    pool: zroot
>   state: ONLINE
>    scan: none requested
> config:
>
>      NAME        STATE     READ WRITE CKSUM
>      zroot       ONLINE       0     0     0
>        da0p3     ONLINE       0     0     0
>
> errors: No known data errors
>
> Anyway it is said :"One or more devices has experienced an error
> resulting in data corruption."
> but a cd to a filesystem of the pool doesn't crashed anymore.
>
> So the questions:
> - why we have to issue a zpool clear in order to recover a "working" pool ?
>
> - is it normal to have possible data corruption (as said in the
> message), what it means exactly ?
>    As we understood normaly the pool should recover enough redondancy
> informations to have a fonctional one,
>    and without possible data corruption, no ?
>
> Thank for you help,
> Best regards
> Jean-Marc & Roland
>
>
> --
> LACROIX Jean-Marc                  office: W612
> Administrateur Systèmes et Réseaux LJAD
> phone:  04.92.07.62.51             fax: 04.93.51.79.74
> email:  jml at unice.fr
> Address: Laboratoire J.A.Dieudonne - UMR CNRS 7351
>           Universite de Nice Sophia-Antipolis
>           Parc Valrose - 06108 Nice Cedex 2 - France
>
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