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"vzctl stop" - hangs [message #23229]

Wed, 14 November 2007 14:20

dagr
Messages: 83
Registered: February 2006

Member

Usually i use kernel 2.6.9 , but now i have to move to 2.6.18 (2.6.18-8.1.15.el5.028stab047.1PAE) and i found out that "vzctl stop" - hangs for exactly 2 mins (start is ok and runs ok )

I found out that it happens only with VEs which use loop mounts ( mount -o loop,ro) - i use them for sharing data among VEs.

I made strace during stop (it helped me once when stop hanged cause couldnt find "halt" binary ), but wasnt able to find out the reason . Anyway i attached strace.txt .

Also i noticed that it doesnt umount clean loop devices .
On prvious kernel i had in .umount

umount  /vz/root/$VEID/vps_static
umount  /vz/root/$VEID/vps_libs

On new kernel i get error

[dagr@ssw2-ca shared_vps]$ date;sudo vzctl stop 1051206;date   
Wed Nov 14 14:05:40 GMT 2007                                   
Stopping VE ...                                                
VE was stopped                                                 
umount                                                         
umount: /u04/vz/shared_vps/php5_base/vps_libs_loop: not mounted
umount: /u04/vz/shared_vps/php5_base/vps_libs_loop: not mounted
Error executing umount script /etc/vz/conf/1051206.umount      
Wed Nov 14 14:07:41 GMT 2007

And i get 1 loop device not detached (from /vz/root/$VEID/vps_libs mount )

[dagr@ssw2-ca private]$ ps -ef| grep loop               
root       601     1  0 14:04 ?        00:00:00 [loop1] 
[dagr@ssw2-ca private]$ sudo losetup -d /dev/loop1

I thought that may be openvz on new kernel somehow handles loop umounts by itself , but if comment .umount file , it leaves all 2 mounts.

(vzctl-3.0.18-1 , ovzkernel-PAE-2.6.18-8.1.15.el5.028stab047.1)

So 2 questions.

1. Whats wrong with stop ?
2. Whats wrong with loop device umount ?

Attachment: strace.txt
(Size: 210.39KB, Downloaded 299 times)

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Re: "vzctl stop" - hangs [message #23273 is a reply to message #23229]

Thu, 15 November 2007 07:36

vaverin
Messages: 708
Registered: September 2005

Senior Member

1) 2 minutes is "vzctl stop" timeout, it waits until VE will be stopped completely. Obviously initscripts iniside your VE are not finished correctly.
Some time ago we have disabled ability to kill init process from inside VE. Now VE's initscripts should call halt or reboot (or any another application that calls sys_reboot syscall) to kill VE's init process and stop it completely.

2) umount problem
Are you sure that external mounts are leaves really? It should be umounted automaticaly on VE stop.

Please take a look at the following Vasily Tarasov's comment:
http://forum.openvz.org/index.php?t=msg&goto=13453&& amp;srch=mount+%2Fetc%2Fmtab#msg_13453:
"The thing is that when you produce mount command on HN (e.g. from .mount script), the entry in /etc/mtab on HN appears. Later when VE stops all mount points in VE are umounted automatically even _without_ umount script. But the entry in /etc/mtab is still there! It makes mount a bit crazy...

So, you should use `mount -n` in mount script and don't use umount script at all."

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Re: "vzctl stop" - hangs [message #23274 is a reply to message #23273]

Thu, 15 November 2007 07:40

vaverin
Messages: 708
Registered: September 2005

Senior Member

Btw, why do not you use bindmounts instead of loop mounts?

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Re: "vzctl stop" - hangs [message #23279 is a reply to message #23274]

Thu, 15 November 2007 08:22

dagr
Messages: 83
Registered: February 2006

Member

cause i need them to be read only

BTW - mount -n helps with error from mtab , but loop devices are still not detached

[dagr@ssw2-ca ~]$ date;sudo vzctl stop 1051206;date  
Thu Nov 15 08:29:05 GMT 2007                         
Stopping VE ...                                      
VE was stopped                                       
umount                                               
VE is unmounted                                      
Thu Nov 15 08:31:06 GMT 2007                         
[dagr@ssw2-ca ~]$ ps -ef| grep loop                      
root     25193     1  0 08:28 ?        00:00:00 [loop0]  
root     25200     1  0 08:28 ?        00:00:00 [loop1]  
dagr     27545 24812  0 08:31 pts/3    00:00:00 grep loop
[dagr@ssw2-ca ~]$ sudo vzctl start 1051206 
Starting VE ...                            
VE is mounted                              
Adding IP address(es): 10.5.1.206          
Setting CPU units: 1000                    
Configure meminfo: 149152                  
Set hostname: vps-1051206.super.vz         
VE start in progress...              
[dagr@ssw2-ca ~]$ ps -ef| grep loop                       
root     25193     1  0 08:28 ?        00:00:00 [loop0]   
root     25200     1  0 08:28 ?        00:00:00 [loop1]   
root     27551     1  0 08:31 ?        00:00:00 [loop2]   
root     27556     1  0 08:31 ?        00:00:00 [loop3]   
dagr     29060 24812  0 08:31 pts/3    00:00:00 grep loop    
[dagr@ssw2-ca ~]$ cat /etc/vz/conf/1051206.mount                                
#!/bin/bash                                                                     
#echo mount                                                                     
mount -n -o loop,ro  /vz/shared_vps/php5_base/vps_static_loop_test  /vz/root/$VEID/vps_static                                                                   
mount -n -o loop,ro  /vz/shared_vps/php5_base/vps_libs_loop   /vz/root/$VEID/vps_libs        
[dagr@ssw2-ca ~]$ cat /etc/vz/conf/1051206.umount  
#!/bin/bash                          
echo umount

So eventually all 255 devices will be exhausted

[Updated on: Thu, 15 November 2007 08:37]

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Re: "vzctl stop" - hangs [message #23285 is a reply to message #23279]

Thu, 15 November 2007 08:47

vaverin
Messages: 708
Registered: September 2005

Senior Member

you can mount loop on the HW node and then bind-mount it to VEs via mount scripts

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Re: "vzctl stop" - hangs [message #23295 is a reply to message #23285]

Thu, 15 November 2007 10:34

dagr
Messages: 83
Registered: February 2006

Member

Hmm , thats a good idea anyway , but not sufficient in my case . One of that loopback mounts holds /usr,/sbin,/bin,/lib. So /etc/init.d/halt script just stalls because fuser shows him that fs still busy. So i had to change this script adding "halt; exit 0;" before umount of loopback devices.

Actually it helps even without using bind mounts. Just need to use mounts which do change /etc/mtab and in umounts add umount string for every loopback.

Anyway my problems are solved , tks.

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