Re: Fwd: [Xen-users] Unable to create more than 1 VM

[jim burns <jim_burn@xxxxxxxxxxxxx>]

On Tuesday June 10 2008 07:40:59 am Thomas wrote:
> Argh it's stuck again! It happens after some amount of time. I only
> have 1 DomU running, I can xm console into it after creating it, but
> if I wait 5-10 minutes, I can't console into it anymore. The DomU is
> fully functionnal, appears in xm list and is not stuck at 100% cpu,
> and I can ssh into it.

Hi Again Thomas. This sounds like a symptom of the getty dying on xvc0. Are 
you getting messages of the form "co:init getty restarting too fast. delaying 
for 5 min." or something to that effect? The syslog is one 
of /var/log/{syslog,messages}.

> > try adding extra='xencons=tty1' to your domU config file
> >
> > and shutdown and start your domU
> >
> > - karsten
>
> Thanks Karsten, I already tried this option and we are almost there, I
> do get the console, but it stops at:
>
> [edited for brevity]
> VFS: Mounted root (ext3 filesystem).
> Freeing unused kernel memory: 240k freed
> Adding 262136k swap on /dev/hda2.  Priority:-1 extents:1 across:262136k
> EXT3 FS on hda1, internal journal
> [End]
>
> Then I don't see any login prompt. There might again an issue in the
> config file, it must be some parameter to add to sort things out. The
> DomU is fully functionnal though, and I can still ssh into it.

This is normal end of boot process messages, but you are not getting a login 
prompt. I remember you had problems adding "co:2345:respawn:/sbin/agetty xvc0 
9600 vt100-nav" to your inittab because you didn't have 'agetty' (which is in 
the util-linux package (SuSE) or util-linux-ng (Fedora), usually in /sbin). 
If you can't find it, try one of the other getty programs in /sbin 
or /usr/sbin. Just as important is to put xvc0 in your /etc/securetty.

> Excerpt:
> -----------------
> When a virtual machine starts, it normally takes the memory that it
> has assigned from the memory that is available to Dom0. Once
> allocated, the Dom0 will never get that memory back, not even when the
> virtual machines are all stopped.
>
> It is dated from 12.04.2007, probably Xen changed its behavior since.
> Can someone confirm?

Nope, still the case, at least if you mean automatically gets it back. You 
have to manually add it back with the 'xm mem-set 0 mem-size' command. It 
makes me nervous to give dom0 more memory than it started out with :-), so 
make sure you remember what 'xm list' said for Domain-0 before you started 
any domus. It's not the same as the amount of memory installed, or even 
what 'xm info' reports. So for each domu that exits, you can add that domu's 
amount of memory to the current amount in 'xm list 0', So for example, on my 
system, even tho' xm info reports:

total_memory           : 2038

my initial dom0 memory is about 1957. So if I have

[535] > xm list
Name                                        ID   Mem VCPUs      State   
Time(s)
Domain-0                                     0   956     2     r----- 192036.6
fedora                                       2   512     1     -b----  22698.5
winxp                                       29   512     2     -b----  23504.2

and kill those two domus, even tho' 956 + 512 + 512 is greater than 1957, I 
wouldn't go higher than 1957 with xm mem-set 0 ...

This really isn't something I worry about unless I start getting error 
messages about not having enough memory to start a domu. Xen *usually* is 
good about reusing freed memory for domus, just not giving it back to dom0. 
Also, setting dom0-min-mem in /etc/xend-config.sxp might give you some peace 
of mind that dom0 will always have what it needs.

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users