Re: [Xen-devel] virtual domain partial boot then crash

["Gregory Newby" <newby@xxxxxxxx>]

Hi, Jefferson.  A few suggestions:

Check /etc/fstab on the other domains (i.e., /dev/hda14).  Your kernel
panic symptom below sounds like it might be trying to mount R+W
without the physical grant -w.

Also, as previously mentioned, don't use "LABEL=/" for the virtual
domains.  You need to supply the actual device node.

So, on your xen1, /etc/fstab might look something like this
(with a physical grant /dev/hda14 -w):

/dev/hda14      /       ext3    defaults 1 1

For RO, which will cause some logging to fail but might
at least let you get further in the boot process:

/dev/hda14      /       ext3    defaults,ro 1 1

It might help to put "0 0" in the last columns, which will
tell the kernel to not fsck the partitions.  Of course,
you should also make sure the partition is umounted from
the zeroth domain before trying to start another one.

I hope this helps!  Another solution is to mount / via NFS 
instead.
  -- Greg


On Sun, Dec 07, 2003 at 06:39:20PM -0800, Jefferson Ng wrote:
> 
> > > Error writing block 269, (Attempt to write block from filesystem
> resulted
> > > in short write) Error writing block 269, (Attempt to write block from
> > > filesystem resulted in short write)
> >
> > I presume you've written a script for domain 1 that does a
> > 'physical grant -phda14 -w' ?   It looks like part of the problem
> > is that you don't have write access to the partition.
> 
> We hadn't...  we were under the impression that physical grant alone gave
> read and write access, which is why we were wary of it.
> 
> This fixes that device's errors.
> 
> > If you still have problems, please can you tell us a bit more
> > about your exact file system configuration, your xenctl.xml file,
> > the scripts you've written to start each domain, etc.
> Great--let us know if there's any other information you think will help us
> narrow down what's going on.
> 
> The filesystem data is included below, along with xenctl.xml,
> xen-mynewdom, and our fstab file.  We have logs from attempts to start xen
> if you'd like to see those too.
> 
> > It's odd that you're having so much trouble as at least as far as
> > I can figure from previous emails you're not trying to setup a
> > configuration that's at all unusual. I'm sure we can get this
> > figured out...
> 
> I think part of the problem is that we're not really strong on kernel
> hacking and linux installation.  I think there's some background that, if
> we had it, would make everything we need help on very plain and obvious.
> 
> We've really just been following instructions step by step and hoping it
> works, and when encountering difficulties it's hard to guess what the
> problem is...  so we just grope around as best we can trying to see what
> could correspond to the error, typing things into google like mad.
> 
> Also, we might not have mentioned this earlier, but earlier than two weeks
> ago we discovered some of our errors were hardware related(the demo CD
> wouldn't run).  (We were running on a PII 400mhz w/256mb RAM). Since then
> we've switched to a PIII 633mhz w/256mb RAM.  So part of our errors were
> not-fixable, earlier on.
> 
> Anyway.  Let us know if we can do anything to make things easier--this
> must be annoying having us ask questions so often =/
> 
>         -Jefferson
> 
> --
> 
> Some quick questions:
> -Should there be directories and utilities inside the roots for each xen
> domain?  When we used the demo CD it had data from the initrd.gz, but
> we're not sure if that's necessary.
> 
> A summary of our errors:
> -If we give a domain a physical grant of our root(/dev/hda2) readonly, we
> get a kernel panic--it says the root is unclean, tries to clean it, and
> finds it doesn't have write access.
> 
> -If we give a physical grant of readwrite to a xen partition(100mb ofempty
> space, /dev/hda14), and readonly to everything else, it tries to
> recover a journal on one of the other xen partitions and runs out of file
> descriptors.
> 
> Data about our filesystem:
> >From df:
> 
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/hda2             16128668   2603208  12706148  18% /
> /dev/hda1               101089     11755     84115  13% /boot
> none                     63820         0     63820   0% /dev/shm
> **these xens are normally unmounted
> /dev/hda5               101089      4127     91743   5% /xen10
> /dev/hda14              101089      4127     91743   5% /xen1
> /dev/hda13              101089      4127     91743   5% /xen2
> /dev/hda12              101089      4127     91743   5% /xen3
> /dev/hda11              101089      4127     91743   5% /xen4
> /dev/hda10              101089      4127     91743   5% /xen5
> /dev/hda9               101089      4127     91743   5% /xen6
> /dev/hda8               101089      4127     91743   5% /xen7
> /dev/hda7               101089      4127     91743   5% /xen8
> /dev/hda6               101089      4127     91743   5% /xen9
> 
> >From /etc/fstab:
> 
> LABEL=/               /                       ext3    defaults        1 1
> /dev/hda1             /boot                   ext3    defaults        1 2
> none                  /dev/pts                devpts  gid=5,mode=620  0 0
> none                  /proc                   proc    defaults        0 0
> none                  /dev/shm                tmpfs   defaults        0 0
> #/dev/hda14           /xen1                   ext3    defaults        1 2
> #/dev/hda5            /xen10                  ext3    defaults        1 2
> #/dev/hda13           /xen2                   ext3    defaults        1 2
> #/dev/hda12           /xen3                   ext3    defaults        1 2
> #/dev/hda11           /xen4                   ext3    defaults        1 2
> #/dev/hda10           /xen5                   ext3    defaults        1 2
> #/dev/hda9            /xen6                   ext3    defaults        1 2
> #/dev/hda8            /xen7                   ext3    defaults        1 2
> #/dev/hda7            /xen8                   ext3    defaults        1 2
> #/dev/hda6            /xen9                   ext3    defaults        1 2
> /dev/hda3             swap                    swap    defaults        0 0
> 
> Our /etc/xenctl.xml file:
> 
> <?xml version="1.0"?>
> <domctl_defaults>
> <domain_name>XenoLinux</domain_name>
> <domain_size_kb>98304</domain_size_kb>
> <domain_image>/boot/xenolinux.gz</domain_image>
> <domain_vifs>1</domain_vifs>
> <root_device>/dev/hda2</root_device>
> <root_args>ro</root_args>
> <args>DOMID=+</args>
> <nw_ip>169.254.1.0+</nw_ip>
> <nw_gw>169.254.1.0</nw_gw>
> <nw_mask>255.255.0.0</nw_mask>
> <nw_nfs_server>169.254.1.0</nw_nfs_server>
> <max_domain_number>1000</max_domain_number>
> <xi_tools_dir>/usr/local/bin/</xi_tools_dir>
> </domctl_defaults>
> 
> Our /etc/xen-mynewdom file:
> domain new
> physical grant -phda14 -w
> domain start
> 
> 
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