Re: [Xen-users] login, SSH, and other issues due to permission on /dev changed after reboot

[Ivan Porro <pivan@xxxxxxxxxxxxx>]

Well, I answer to myswlf.

SLC3 is RHEL3, a 2.4 kernel based distribution, and use  devfs
SLC4 is RHEL4, a 2.6 kernel based distribution, and use  udev

Now the question is: what is the better solution?

a) unique kernel compiled by hand with both udev/devfs support
b) two distinct dom0 and domU kernels
c) others ?

Is this a Xen 3.0.2  "problem" only?

thank you in advance,
ivan

Ivan Porro wrote:
> Hi all,
>
> I've a small setup of Xen 3 with scientific linux cern 4.3 dom0 and 
> scientific linux cern 3.06 and 4.3 on few domUs
> Kernel used is 2.6.16-xen3_86.1_rhel4.1.   I've domU images on files 
> on a partition of dom0. This partition is also exported with NFS 
> (another dom0 for domain migration is plannes, and if I'm not wrong,  
> the only option there is to have domU partitions stored on files)
> Everything is apparently fine, except the problem of wrong permissions 
> on /dev entries. This happens only on Scientifc Linux 3.06 (RHEL3) 
> domUs. I've "upgraded" them to kernel26 following CERN instructions 
> (http://linux.web.cern.ch/linux/scientific3/docs/kernel26.shtml) so 
> modutils are ok. After some testing I've found
> that devices are in place with wrong permissions.
>
> I don't know if these are relate issues, but in the past I was not 
> able to install an Oracle10 XE on a 3.0.6 domU and actually, an Apache 
> 1.3/PHP 5.1.2 server seems to crash randomly while connecting via 
> Oracle instant client (OCI8 APIs) to a Oracle server.  I can only 
> guess that my setups are influenced by a mad /dev configuration, so 
> I'm trying to investigate that before going deep into application issues.
> Wrong permission on /dev broke for sure other things, becuase SSH from 
> domU to other hosts doesn't work (permissions on /dev/random and 
> /dev/urandom, on /dev/zero... )
> Making right permissions on /dev is off course a solution but after a 
> reboot the permissions are wrong again:
> # su - myuser
> bash: /dev/null: Permission denied
> ...
> [myuser]$
>
> # chmod a+rw /dev/*
> # su - myuser
> [myuser]$
>
> ... reboot ...
>
> # date
> Thu Aug 24 11:33:01 CEST 2006
> # ll /dev/null
> crw-------    1 root     root       1,   3 Aug 24 11:32 /dev/null
>
> my config file for domU is:
>
> kernel = "/boot/vmlinuz-2.6-xen"
> ramdisk="/boot/initrd-2.6-xen.img"
> memory = 512
> name   = "myhost"
> extra  = "nousb selinux=0  3"
> vif    = [ 'mac=00:16:3e:00:10:11, bridge=xenbr0' ]
> disk   = ['file:/export/virtual_disks/myhost/root.img,hda1,w'
>         ,'file:/export/virtual_disks/myhost/data.img,hda2,w'
>         ,'file:/export/virtual_disks/myhost/swap.img,hda3,w'
>         ]
> root   = "/dev/hda1 ro"
>
> fstab look like:
>
> /dev/hda1                /                       ext3    
> defaults        1 1
> /dev/hda2                /opt                       ext3    
> defaults        1 1
> none                    /proc                   proc    
> defaults        0 0
> none                    /dev/shm                tmpfs   
> defaults        0 0
> none                    /dev/pts                devpts  
> gid=5,mode=620        0 0
> /dev/sys                /sys                    sysfs   
> defaults        0 0
> /dev/hda3         swap                    swap    defaults        0 0
> dom0_IP_address:/scratch   /scratch                nfs     
> rw              0 0
> Mounted filesystems are apparently ok:
>
> $ mount
> /dev/hda1 on / type ext3 (rw)
> none on /proc type proc (rw)
> none on /dev/pts type devpts (rw,gid=5,mode=620)
> /dev/hda2 on /opt type ext3 (rw)
> none on /dev/shm type tmpfs (rw)
> /dev/sys on /sys type sysfs (rw)
> dom0_IP_address:/scratch on /scratch type nfs (rw,addr=130.251.10.160)
>
>
> Thank you in advance,
>
>  Ivan

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