Xen devel - Feb 2004 - Fw: Experience, and questions in using Xen 1.2 with new control tool

This is just a resend of my previous email that I mistakenly have sent to the
mail list admin rather than the list.


----- Original Message ----- 
From: Yan-Ching CHU 
To: xen-devel-admin@lists.sourceforge.net 
Cc: Ian Pratt ; cs0u210a@liverpool.ac.uk 
Sent: Tuesday, February 03, 2004 4:34 AM
Subject: Experience, and questions in using Xen 1.2 with new control tool


Hi all,

    ''Great work!'' to The Xen team. In general I think the
hypervisor is much more stable and the control tool is much more coherent and
centralized in v1.2.

    Although I encountered some problems (below) in installing multiple
domains'' filesystems in my harddrive and it has been a long day to fix
them, after everything is ready one can be familiar with the new tool very
quickly. With just some alias and shell script I can use multiple configs for
different domains and use the general control tool to play with them
comfortably.

    Some questions and remarks:

    1) After starting new domain I can only ssh to it by ''ssh
root@169.254.1.x'' but not as what in the README.CD of Xen 1.2 (and
earlier) says to ssh with port number 2200 + domain_id, if so I would get
connection refused. I have started ''xen_nat_enable'' am I
setting anything wrong or missing anything? Or just leave it?

    2) ''xc destroy'' is so powerful that it can kill Domain 0
directly without even a checking or a prompt, if the admin (likely be root)
accidentally key in 0 and enter without serious checking this may cause
troubles.

    3) I am using 256MB in my laptop running 128MB for domain 0, but I
can''t use up the rest of the memory for other domains. Is there any
upper bound? By the way I have tried running a domain by just using 8MB memory
and ssh it successfully. (2MB is not enough for kernel and 4MB with applications
complaining not enough pages) And one more is that if there is not enough memory
the return message will be ''error creating domain'', it would
be useful if it can point to something related to memory.

    4) I am not sure if the suspend/restore function is ready. But I have tried
Create->Stop->Save a domain and Restore->Start it again. The network
interface and sshd seem totally down after restore, if the sshd is down seems
there is no way to rescue it (will this push the read/write console for domains
upper on the to-do list?:-)

        The ''cpu_time'' displayed by ''xc
list'' of the saved and then restored domain seems not accurate, I am
not entirely sure about this I will try to reproduce and report later. Be aware
that the restore function starts the domain in the newest domain_id rather than
it''s orginal id, so the IP address of it would look different to the
new domain_id after restored. I have experieced once (I remember when using just
8/16MB memory) that after a domain is restored it keeps generate error message
like the followings, is this normal?

==========================================================DOM17: EXT3-fs error
(device hd(3,11)) in ext3_reserve_inode_write: IO failure
DOM17: EXT3-fs error (device hd(3,11)): ext3_get_inode_loc: unable to read inode
 block - inode=2862, block=93
DOM17: EXT3-fs error (device hd(3,11)) in ext3_reserve_inode_write: IO failure
DOM17: EXT3-fs error (device hd(3,11)) in ext3_orphan_add: IO failure
DOM17: EXT3-fs error (device hd(3,11)): ext3_get_inode_loc: unable to read inode
 block - inode=2862, block=93
DOM17: EXT3-fs error (device hd(3,11)) in ext3_reserve_inode_write: IO failure
DOM17: EXT3-fs error (device hd(3,11)): ext3_get_inode_loc: unable to read inode
 block - inode=2862, block=93
==========================================================
    5) Just a minor one, in the README.CD for Xen1.2 (and before), in the
section "Installing the file systems from the CD", when copying the
files to /usr the directory ''root'' is included, which seems
not appropriate. And there were some directories inside
''local'' which don''t seem appropriate (some personal
files I think) as well, which you may not want to include in the next ISO.
Can''t wait to see the official Xen 1.2 really.

    Hope this helps. More to come.

Cheers,
Yan-Ching CHU