zfs discuss - Nov 2007 - cannot mount ''mypool'': Input/output error

Hello, 

I have a question about using ZFS with Fuse.  A little bit of background of what
we''ve been doing first...  We recently had an issue with a Solaris
server where the permissions of the main system files in /etc and such were
changed.  On server restart, Solaris threw an error and it was not possible to
log in, even as root.

So, given that it''s the only Solaris machine we have, we took out the
drive and after much trouble trying with different machines, we connected it to
Linux 2005 Limited Edition server using a USB to SATA connector.  The linux
machine now sees the device in /dev/sda* and I can confirm this by doing the
following:

[root]# fdisk sda 

Command (m for help): p 

Disk sda (Sun disk label): 16 heads, 149 sectors, 65533 cylinders 
Units = cylinders of 2384 * 512 bytes 

Device Flag    Start       End    Blocks   Id  System 
sda1          1719     11169  11264400    2  SunOS root 
sda2  u          0      1719   2049048    3  SunOS swap 
sda3             0     65533  78115336    5  Whole disk 
sda5         16324     65533  58657128    8  SunOS home 
sda6         11169     16324   6144760    7  SunOS var 

Given that Solaris uses ZFS, we figured to be able to change the permissions,
we''ll need to be able to mount the device.  So, we found Fuse,
downloaded, installed it along with ZFS.  Everything went as expected until the
creation of the pool for some reason.  We''re interested in either sda1,
sda3 or sda5, we''ll know better once we can mount them...

So, we do ./run.sh & and then the zpool and zfs commands are available.  My
ZFS questions come here, once we run the create command, I get the error
directly:

[root]# zpool create mypool sda 
fuse: mount failed: Invalid argument 
cannot mount ''mypool'': Input/output error 

However, if I list the pools, clearly it''s been created: 

[root]# zpool list 
NAME                    SIZE    USED   AVAIL    CAP  HEALTH     ALTROOT 
mypool                 74.5G     88K   74.5G     0%  ONLINE     - 

It seems the issue is with the mounting, and I can''t understand why: 

[root]# zfs mount mypool 
fuse: mount failed: Invalid argument 
cannot mount ''mypool'': Input/output error 

[root]# zfs mount 

I had searched through the source code trying to figure out what argument was
considered invalid and found the following:

    477     if (res == -1) {
   478         /*
   479          * Maybe kernel doesn''t support unprivileged mounts, in
this
   480          * case try falling back to fusermount
   481          */
   482         if (errno == EPERM) {
   483             res = -2;
   484         } else {
   485             int errno_save = errno;
   486             if (mo->blkdev && errno == ENODEV &&
!fuse_mnt_check_fuseblk())
   487                 fprintf(stderr, "fuse: ''fuseblk''
support missing\n");
   488             else
   489                 fprintf(stderr, "fuse: mount failed: %s\n",
   490                         strerror(errno_save));
   491         }
   492 
   493         goto out_close;
   494     }

in the following file: 

http://cvs.opensolaris.org/source/xref/fuse/libfuse/mount.c 

I didn''t really understand what that was suggesting the issue was,
other than the comment saying "unprivileged mounts"... I looked on
http://docs.sun.com/app/docs/doc/819-2240/zfs-1m and found a command:

zfs allow [-ldug] "everyone" |user |group [,,....] 
-[uge] "everyone" |user |group [,,....] 
Specifies to whom the permissions are delegated. Multiple entities can be
specified as a comma-separated list. If none of the -uge options are specified,
then the argument is interpreted preferentially as the keyword ?everyone?, then
as a user name, and lastly as a group name. To specify a user or group named
everyone?, use the -u or -g options. To specify a group with the same name as a
user, use the -g options.

However, when I tried it, it was not recognized: 

[root]# zfs allow 
unrecognized command ''allow'' 

Any thoughts or suggestions would be much appreciated! 

Thank you very much
 
 
This message posted from opensolaris.org

I appreciate the different responses that I have gotten.  As some of you may
have realized I am not a guru in Linux / Solaris...

I have been trying to figure out what file system my Solaris box was using... I
got a comment from Paul that from the fdisk command he could see that most
likely the partitions are Solaris UFS... I don''t see that information
anywhere, so I''m wondering if I missed something, or if you are
assuming this Paul?

I am sure I will not use ZFS to its fullest potential at all.. right now
I''m trying to recover the dead disk, so if it works to mount a single
disk/boot disk, that''s all I need, I don''t need it to be very
functional.  As I suggested, I will only be using this to change permissions and
then return the disk into the appropriate Server once I am able to log back into
that server.

I will try the zfs import just to give it a go.  I have done modprobe fuse and
have it loaded... but the fact that allow is not available in the latest version
clears up why that wasn''t working...

Sorry Darren, I was not sure what the CC Forums really did and I just chose ones
that I thought might be related to ZFS not realized that Crypto is probably
another project...

I got another suggestion that the file system is UFS, which would make me think
that mount -t ufs /dev/sda1 /mnt/mymount should work, but given that that fails
with

mount: wrong fs type, bad option, bad superblock on /dev/sda1,
       or too many mounted file systems

some thing is not right... but that''s probably more a linux community
discussion topic... thanks thought.

Thanks for your suggestion Mark, I will look in the linux FUSE although I do
have a feeling we downloaded the Solaris FUSE software and put it on a linux
box... I''ll have to look into that some more.

Thank you for your responses...
 
 
This message posted from opensolaris.org

On Nov 15, 2007 9:42 AM, Nabeel Saad <nabeel at percussion.com>
wrote:
> I am sure I will not use ZFS to its fullest potential at all.. right now
I''m trying to recover the dead disk, so if it works to mount a single
disk/boot disk, that''s all I need, I don''t need it to be very
functional.  As I suggested, I will only be using this to change permissions and
then return the disk into the appropriate Server once I am able to log back into
that server.
(Sorry, forgot to CC the list.)

Ok, so assuming that all you want to do is mount your old Solaris disk
and change some permissions, then there is probably an easier solution
which is to put the hard drive back in the original machine and boot
from a (Open)Solaris CD or DVD.  This eliminates the whole Linux/FUSE
issues you''re getting into.  Your easiest option might be to try the
new OpenSolaris Developer Preview distribution since it''s actually a
Live CD which would give you a full GUI and networking to play with.

http://www.opensolaris.org/os/downloads/

Once the Live CD boots, you should be able to mount your drive to an
alternate path like /a and then change permissions.  If you boot from
a regular Solaris CD or DVD it will start the install process, but
then you should be able to simply cancel the install and get to a
command line and work from there.

Good luck!

Regards,
-Eric