Re: [Xen-users] why errors happen when two vms start concurrently ?

[Bryant Kobe <shijie1234321@xxxxxxxxx>]

hello, Grant ,

other vms can also be started after these two errors occurred in 

my server , even the vm just error happened can also be started 

if you reexecute " xm start *** ". 

I have printed many logs in xend source code , but find no implies.

I've no idea what the next direction I should go to solve the problem. 

I don't want to change my system .

Bryant

2011/12/22 Grant McWilliams <grantmasterflash@xxxxxxxxx>

On Wed, Dec 21, 2011 at 7:03 PM, Bryant Kobe <shijie1234321@xxxxxxxxx> wrote:

Hello , All ,

when I start two vms used VHD as virtual disk concurrently , the two return errors sometimes ,

they return different errors :

one is :

Error: Device 51952 (tap2) could not be connected. Hotplug scripts not working.

the other is : 

Error: Device 0 (vif) could not be connected. Hotplug scripts not working.

if I start one after another , it works well .

how does it happen ?

xen : 4.1.2

dom0 : centos5.6

domU : centos5.6

Thanks in advance !

Bryant

Yeah, I battled that forever and finally gave up. It gets better if you're using LVM for disks (and you're not limited to somewhere around 100 disks). I finally put a 30 second wait time in my scripts that started my VMs because I often started 50 at one time. This means it would take 25 minutes to start them but they'd start reliably. I also added a wait in there so every 4 that started it would wait until they were booted up before going on. 

I've since moved to XCP and I can start all 50 at the same time without issues and it doesn't seem to matter what kind of disks I have. I can now start 50 and have the prompt back in a matter of minutes.

Sorry I don't have a better answer for you. Sometimes after I'd get that error I wouldn't be able to start ANYTHING again until a reboot. That was on Xen 3.4.

Grant McWilliams
http://grantmcwilliams.com/

Some people, when confronted with a problem, think "I know, I'll use Windows." 
Now they have two problems.

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