Difference between revisions of "Frequently Asked Questions"

== General ==

{{Question

|Question=What is a 'Guest'?

||Details=To talk about stuff, we need some naming. The physical machine is called 'Host' and the 'main' context running the Host Distro is called 'Host Context'. The virtual machine/distro is called 'Guest' and basically is a Distribution (Userspace) running inside a 'Guest Context'.

|Signature=derjohn}}

{{Question

|Question=What kind of Operating System (OS) can I run as guest?

||Details= With VServer you can only run Linux guests. The trick is that a guest does not run a kernel on its own (as XEN and UML do), it merely uses a virtualized host kernel-interface. VServer offers so called security contexts which make it possible to separate one guest from each other, i.e. they cannot get data from each other. Imagine it as a chroot environment with much more security and features.

|Signature=derjohn}}

{{Question

|Question=Is this a new project? When was it started?

||Details=The first public occurrence of Linux-VServer was Oct 2001. The initial mail can be found here: http://www.cs.helsinki.fi/linux/linux-kernel/2001-40/1065.html

|Signature=derjohn}}

{{Question

|Question=Which distributions did you test?

||Details=Some. Check out the wiki for ready-made guest images. But you can easily build own guest images, e.g. with Debian's debootstrap. Checkout [[Building Guest Systems]] how to do that.

 

 

 

 

 

 

||Details=Well, [http://www.nongnu.org/util-vserver/doc/conf/configuration.html this page] contains all configuration options for util-vserver. The name of the page is derived from the stylesheet(s) it contains.

 

 

 

 

||Details=Yes ....

* CPU usage: Dynamically (token bucket)

|Signature=derjohn}}

{{Question

|Question=Resource limiting?

||Details=You can put limits per guest on different subsystems.

* using ulimits and rlimits (rlimit is a new feature of kernel 2.6/vs2.0.) per guest, to limit the memory consumption, the number of processes or file-handles, ... : see [[Resource Limits]]

Note that you can only offer guaranteed resource availability with some ticks at the time.

 

# Check the size of memory pages. On x86 and x86_64 is usually 4 KB per page. (on linux "getconf -a|grep PAGE" will give you the information)

# Limit the guests physical RAM to value smaller then maxram:<pre>echo %%insertYourPagesHereSmallerThanMaxram%% > /etc/vserver/<guest>/rlimits/rss </pre>

# Limit the guest's maximum number of as pages to a value smaller than (maxram+maxswap): <pre> echo %%desiredvalue%% > /etc/vserver/<guest>/rlimits/as </pre>

It should be clear this can still lead to OOM situations. Example: You have two guests and your as limit per guest is greater than 50% of (maxram+maxswap). If both guests request their maximum at the same point in time, there will be not enough mem .....

|Signature=derjohn}}

The default since 2.6.18 in Sept 2006 is CFQ, described below, and prior to that was anticipatory a.k.a. "AS" ([[http://en.wikipedia.org/wiki/CFQ#Kernel_2.6.18_.2820_September_2006.29 Wikipedia]]). When running several guests on a host you probably want the I/O performance shared in a fair way among the different guests. The kernel comes with a "completely fair queueing" scheduler, CFQ, which can do that. (More on schedulers can be found at http://lwn.net/Articles/114770/)

# grep cfq /etc/sysfs.conf

|Question=Nice disk I/O scheduling, is that possible?

||Details=Well, since linux 2.6.13 processess have another priority next to the cpu nice scheduling hint, it's called io nice.

It's split into three groups, called real-time, best effort and idle. The default is best-effort, but within best-effort, you can have a niceness from 0 to and including 7.

You can set this niceness by the tool ionice, which for debian is either in the package util-linux or schedutils.

To change the io-niceness you need the <tt>CAP_SYS_NICE</tt>, '''and''' need to have the same uid as the processe you want to ionice.

:'''Note:''' If you want to use any schedulung other than best-effort you will also need the <tt>CAP_SYS_ADMIN</tt>-flag. Be warned that this gives quite some capabilities to the vserver, not just for I/O scheduling!

If you want to increase the niceness of an I/O hogging process within a vserver you need to do:

chcontext --xid sponlp1 sudo -u '#2089' ionice -c2 -n5 -p24409

with sudo and ionice installed on the root server to increase the *nice*ness of pid 24409, with uid 2089

|Signature=Groteblup}}

{{Question

|Question=I want iotop to display all guest processes on host to give me a nice overview of I/O usage.

||Details=You must allow iotop to read information from all guests. Add

# setattr --watch /proc/vmstat

to, for example, rc.local, and later run iotop:

ln -s /vservers/.hash /etc/vservers/.defaults/apps/vunify/hash/root

In order for the OS cache to benefit from the hardlinking, you'll have to restart the vservers.

To clean up hashified files that are no longer referenced by any vserver, do (possibly from a cronjob):

find /vservers/.hash -type f -links 1 -print0 | xargs -0 rm

Until you do this, the files still take up place even though no vservers need them.

|Signature=Guy-}}

== Filesystem usage ==

{{Question

|Question=Is there a way to implement "user/group quota" per VServer?

||Details=Yes, but not on a shared partition for now. You need to put the guest on a separate partition, setup a vroot device (to make the quota access secure), copy that into the guest, and adjust the mtab line inside the guest. If 8 vroot device is not enough for you, you can add more with the kernel parameter max_vroot (exemple for built in kernel vroot /vmlinuz-2.6.31.6-vs2.3.0.36.26aq root=/dev/md1 ro max_vroot=20 ). If vroot is a module you'd actually want to put for exemple "options vroot max_vroot=20" in /etc/modprobe.conf and then just do modprobe vroot

|Signature=derjohn,gadnet}}

{{Question

|Question=What about "Quota" for a context? Howto limit disk usage?

||Details=Context quotas are now called Disk Limits (so that we can tell them apart from the user/group quotas :). They are supported out of the box (with vs2.0+) for all major filesystems (ext2/3, ReiserFS, JFS). You need to tag the FS with XID (see below). Please read [[Disk Limits and Quota]] for more information.

|Signature=derjohn}}

{{Question

|Question=How do I tag a guest's directory with xid?

||Details=Tagging the guest's files gives you several advantages, e.g. the accounting will work properly.

Filesystem XID tagging only works on supported filesystem. Those are currently: ext2/3, reiserfs/reiser3, xfs and jfs.

To activate the XID tagging you have to mount the filesystem with "-o tag" (former tagxid is outdated since VS2.2). Attention: It's _not_ possible to "-o remount,tag", you have to mount it freshly. The guests will tag their files automatiaclly. If you copy files in from the host, you have to tag them manually like this:

Note: Context 0 and 1 will see all files, guests will only be able to access untagged files and their own XID. They can see other XID files but no information about the file, e.g. no owner, no group, no permissions.

Note: It is not advised to tag the root filesystem, as [http://www.paul.sladen.org/vserver/archives/200602/0020.html explained by Herbert] : trying to do so will expose you to some troubles !

|Signature=derjohn_and_gonzo_and_are}}

{{Question

|Question=How can I copy anything from host to guest partition, normally unvisible on host?

vnamespace --enter <xid> -- /bin/bash

 

|Question=Why is the barrier attribute disappearing on reiserfs filesystem after umount or host reboot?

||Details=The filesystem has to be mounted with explicitly defining the 'attrs' option, i.e.

mount /dev/reiserfsdev /vservers -oattrs

setattr --barrier /vservers

to get the barrier survive after umount/reboot.

 

 

 

||Details=For now the networking is 'Host Business' -- the host is a router, and each guest is a server. You can set the capability ICMP_RAW in the context of the guest, or even the capability CAP_NET_RAW (which would even allow to sniff interfaces of other guests!). Likely to change with ngnet.

|Signature=derjohn}}

 

</pre>

|Signature=derjohn}}

 

|Signature=BenjaminGreen}}

{{Question

|Question=If my host has only one a single public IP, can I use RFC1918 IP (e.g. 192.168.foo.bar) for the guest vservers?

||Details=Yes, use iptables with SNAT to masquerade it.  

See: [[HowtoPrivateNetworking]] and  

http://www.tgunkel.de/it/software/doc/linux_server.en#h3-VServer_Masquerading_SNAT (THX, [MUPPETS]Gonzo)

|Signature=derjohn}}

{{Question

|Question=If I shut down my vserver guest, the whole Internet interface ethX on the host is shut down.  What happened?

||Details=When you shut down a guest (''i.e. vserver foo stop''), the IP is brought down on the host also. If this IP happens to be the primary IP of the host, the kernel will not only bring down the primary IP, but also all secondary IP addresses. Similarly, if your guests bring up IPs of more than one subnet, all other IPs from a specific subnet will be shut down if you stop the guest which created the first ("parent") IP.

 

You can check this on the host using the command "ip addr show". Example output:

    inet 192.168.249.172/27 brd 192.168.249.191 scope global eth0

    inet 192.168.234.194/27 brd 192.168.234.223 scope global eth0

In this example, if you stop the guest which brings down the IP 192.168.249.172, the IP 192.168.249.169 will be brought down as well, because it is a secondary IP of the "parent" 192.168.249.172.

{{Question

|Question=Can I run an OpenVPN Server in a guest?

Yes. To get a OpenVPN Server running in a guest, all networking setup has to be done on the host. This answer describes the common case and shows some pitfalls, for detailled information about OpenVPN, please consult the appropriate documentation on the OpenVPN homepage.

This is the minimal OpenVPN configuration for the Server which will be used to demonstrate how to get it running in a client:

ifconfig-noexec

comp-lzo

persist-key

# cd /var/lib/vserver/<myopenvpnserver>/dev/

==> /etc/vservers/<myopenvpnserver>/interfaces/1/nodev <==

</pre>

<br>If you really, really, really need iptables on the guest and you are aware about loosing a big part of VServer isolation and security you could add the NET_ADMIN capability. Consider writing wrappers to manage iptables on the host instead.

[[http://jim.studt.net/depository/index.php/notes-on-linux-s-macvlan-module Reference]]

|Signature=bobnormal&swenTjuln

}}

{{Question

|Question=Is it possible to hide packet counters on the host network interface from vServer guests?

 

|Question=Services won't bind to 127.0.0.1 when I configure them to bind to all available IPs / (binding service to * doesn't bind to loopback)?

||Details=You've configured single public IP and have kernel option "Linux VServer -> Automatic Single IP Special Casing" enabled.

  * disable the auto single IP in the kernel

  * assign more than one IP to the guest

 

At runtime to avoid restarting the vserver: nattribute --set --nid <guest> --flag ~single_ip

 

|Question=When using network namespaces and vserver together, netstat does not work in the vserver. What's wrong?  

||Details=All proc entries are hidden by default in the guests. During startup of the host system a tool called vprocunhide makes some /proc files visible.

 

If you create a new network namespace you have to do the same in the network namespace because the new /proc/net files are not available for the vprocunhide outside the new network namespace. So something like that should be sufficient to get netstat working in vservers with network namespaces:

ip netns exec $NAMESPACE /usr/lib/util-vserver/vprocunhide

== Administration tools ==

{{Question

 

 

 

|Question=I run a Debian host and want to build an Ubuntu guest. Howto?

||Details=Simple ;) Assume you want to build a breezy guest on a sid host with IP 192.168.0.2 and hostname vubuntu, then do:

  The knowledge how to build ubuntu 'breezy badger' (which you probably want to be your guest at the time of writing) has been added recently.

|Signature=derjohn}}

|Question=I want to build a Gentoo guest. Howto?

||Details=Even simpler ;) See http://www.gentoo.org/proj/en/vps/vserver-howto.xml#doc_chap3 .

|Signature=gcc}}

== Application level problems ==

{{Question

|Question=When I try to ssh to the guest, I log into the host, even if I installed sshd on the guest. What's wrong here?

||Details=Look at /etc/ssh/sshd_config of the host:

Do I have to explain more? If the hosts sshd binds all available IP addresses on port 22 (The hosts 'sees' even all addresses of the guests!). So if the guest starts its sshd, it can't bind to port 22 any more. You need to change that setting only on the host.  

{{Question

|Question=Bind9 does not like to start in my guest.

||Details=Check out the [[Problematic Programs]] page and/or get my [http://linux-vserver.derjohn.de/bind9-packages/bind9-capacheck_9.3.2-2_i386.deb vserver-guest-ready Debian package] for Debian Sid guests and check out the [http://linux-vserver.derjohn.de/bind9-packages/README.txt readme]. (Hint: This is fresh stuff. Please give me feedback)

[UPDATE] Since VServer Devel 2.1.1-rc18 you do not need to patch the userland tools anymore. The capabilities are masked.

|Signature=derjohn}}

{{Question

|Question=My mysqld running in a guest behaves strangely and is awfully slow/locks up

||Details=This can be related to /tmp being too small. mysqld stores temporary tables in /tmp and as such, if a lot of queries happen and /tmp runs full this can cause one query to lock up whilst creating the tmp table and all other queries waiting to acquire the lock. There are two possible solutions to that problem: a.) Modify /etc/vservers/vserver-name/fstab and assign more memory to the tmpfs of /tmp and b.) remove the /tmp entry from /etc/vservers/vserver-name/fstab completly. Especially on database servers with a rather high load the second one might be the preferred method.

If you prefer not to modify or disable tmpfs, you can reconfigure MySQL to use a different tmpdir such as "/var/tmp".  For example, edit /etc/my.cnf (RHEL/CentOS) or create /etc/mysql/conf.d/mysqld_custom.conf (Debian) and add the following line:  

</pre>

Afterwards, restart MySQL (/etc/init.d/mysqld restart) and then review MySQL variables (mysqladmin -uroot -p variables) to confirm "tmpdir" is no longer pointing to "/tmp". |Signature=sp, jrklein}}

pam authentication (also used with openssh) enables "pam_loginuid.so" in the /etc/pam.d/* files. Comment those out as they are not necessary and will not load within a guest anyway. This probably is also necessary on updates later on, if the configs get changed. You therefore may add the following command line to a cronjob file or your software update script:

<pre>

/bin/sed --in-place -e "s/^session.*required.*pam_loginuid.so/# session\trequired\tpam_loginuid.so/g" /etc/pam.d/*

</pre>

'''UPDATE:''' If you are compiling your own kernel this can be fixed system-wide by setting CONFIG_AUDIT_LOGINUID_IMMUTABLE=n in kernels .config file.

|Signature=patrick, SwenTjuln}}

{{Question

|Question=How do i install nagios-plugins on a Gentoo guest?

||Details=Unfortunately, the nagios-plugins ./configure scripts wants to ping 127.0.0.1 which is not available inside a guest. Therefore you have to build nagios-plugins outside the guest.

vnamespace -e <xid> -- chroot /vservers/<name> emerge nagios-plugins -va

</pre>

|Signature=Hollow}}

 

||Details=At least on Debian, I can tell you how to do it with the new-style config. If your guest is called "derjohn" and you want it to be started somewhere at the of your bootstrap process, then do:

echo "default" > /etc/vservers/derjohn/apps/init/mark

||Details=To start all vservers with a mark value of <tt>foo</tt>, you can use something like:

MARK=foo NUMPARALLEL=42 LOCKFILE=vserver-foo /path/to/util-vserver/vserver-wrapper start

If you want to automate this, you can create a copy of the <tt>/etc/init.d/vservers-default</tt> script called <tt>/etc/init.d/vservers-foo</tt>, set <tt>MARK</tt>, <tt>NUMPARALLEL</tt> and <tt>LOCKFILE</tt> appropriately in it, and have it start at whatever point in the boot process.|Signature=Guy-}}

 

|Question=What is old-style and new-style config?

 

For legacy Linux-VServer (i.e. 1.2.x), you have to replace /sbin/halt in the guests with vreboot and start rebootmgr in the host. You also need to have a <guest>.conf file in /etc/vservers for each guest. Please have a look at /etc/init.d/rebootmgr.

 

||Details=By default, vserver uses the 'sysv' startup style, which mimics the init process by running the 3rd runlevel through '/etc/init.d/rc 3' (or '/etc/rc.d/rc 3'). Usually this 'rc' script uses a hard-coded PATH. In the case it doesn't, util-vserver also mimics init's default PATH through /etc/vservers/.defaults/apps/init/environment, or if not present /usr/local/lib/util-vserver/defaults/environment. Beware that all those default PATH usually do not include /usr/local.

 

 

 

 

 

 

 

||Details=If you have the choice make the host a 64 bit one. You can run a guest as 32 bit or as 64 bit on a 64 bit host. To run it as 32 bit, you need to compile the x86_64 (a.k.a. AMD64) with the following options:

[*] IA32 Emulation <---- without that, the entire 32bit API is not present

But you can force debootstrap to put 32 bit binaries into the guest by 'export ARCH=i386';

newvserver --arch i386 ...

--arch=amd64  (or i386 if you want 32bit)

|Question=What does the guest privacy option do in the kernel settings ?

> > Does it just prevent the spectator context ?

- iopriority

> > What security do it bring to the system ?

together with the VXF_STATE_ADMIN it can be

used to secure a guest (to some degree) from

|Question=VServer is included in the stable Debian GNU/Linux for years now. What VS version did they include?

||Details=There is no support in Debian for Linux-Vserver since the Wheezy release. Debian Squeeze included a 2.6.32 based kernel-package called 2.6.32-5-vserver-ARCH. This contained VServer 2.3.0.36.29.6 with some additional fixes.

|Question=Were can I get newer versions of VServer as ready made packages for Debian?

* http://repo.psand.net/info/ has Debian Lenny, Squeeze and Wheezy repositories. Many kernel versions are present. Currently (Febraury 2013) 3.2 kernels are being maintained for Wheezy, with additional packages for 3.4 and 3.10 also available. Architectures available are i386 and amd64. This repository also contains curremt util-vserver builds. Build will shortly begin for Jessie.

* http://www.lihas.de/anleitungen-und-service/linux-vserver-kernel-fuer-debian/linux-vserver-kernel-english details their automatically built repository currently for 3.4 kernels. Building, patching and testing for the kernels is automated.

Older unmaintained repositories are/were here:

* http://linux-vserver.derjohn.de/ - "my kernels are always 'devel' branch" (derjohn). This repo contain kernels up to 2.6.29 for amd64, 2.6.26 for i386.

* http://backports.debian.org/ contains 2.6.32 backports for Lenny at time of writing (11th May 2010)

* http://zbla.net/debian/ Unofficial debian vserver packages '''WARNING : i386 packets are compiled for 64bits !''' apt source line: ''deb http://zbla.net/debian/ ./'' (N/A as of 2011/12/27)

*http://repo-ubuntu.psand.net/dists/ is the only repository maintained for Ubuntu. It covers the same builds as http://repo.psand.net/info/ - and information there should be used, replacing 'precise' as distro in your /etc/apt/source.list.

||Details=Device nodes allow userspace to access hardware (or virtual resources). Creating a device node inside the guest's namespace will give access to that device, so for security reasons, the number of 'given' devices is small.

# vnamespace -e XID  mount -t tmpfs -o remount,size=256m,mode=1777 none /var/lib/vservers/<guest>/tmp/

(if there's a problem, try expanding the symlinks in the mount path)

Be warned that the guest will not recognize the change, as the /etc/mtab file is not updated when you mount like this. To permanently change the mount, edit /etc/vserver/<guest>/fstab on the host.

vnamespace -e builder chroot /var/lib/vservers/<guest>/ mount -o remount,size=64m,mode=1777 /tmp

To understand the other way, let me explain how mount namespaces work.

Every guest has two mount namespaces associated with it: one "''management namespace''" and one "''operational namespace''".

On starting the guest, first the management namespace is created as a copy of the host namespace (which means that everything that was mounted on the host is mounted in the new namespace as well). This has unwelcome side effects: for example, if you had a cdrom mounted while starting the guest, you wouldn't be able to eject it until you stop the guest even if you umount it on the host, because it's still mounted in the guest. Therefore, the namespace is ''cleaned up'': filesystems that are mounted outside the root of the guest get unmounted in the guest namespace.

Subsequently, the operational namespace of the guest is created as a copy of the management namespace, and the guest's processes are started in it.

Let's assume, as an example, that we want a guest to see a subdirectory, called <tt>foo</tt>, of the cdrom we just mounted on the host (e.g. under <tt>/media/cdrom</tt>).

 

# vnamespace -i 0 -e <guest-xid> -- /bin/bash

Now you have access to all host devices; mount the device that contains your directory wherever you want, but you may prefer to mount it in the same location you used on the host. (Note, though, that it's not even necessary for the device to be mounted in the host namespace at all.)

It's likely best to use <tt>mount -n</tt> lest your host <tt>/etc/mtab</tt> get polluted with mounts from other namespaces.

 

We're now back in the host namespace. <tt>vmount</tt> can now be used to bind mount <tt>/media/cdrom/foo</tt> inside a running guest (in this example, under <tt>/foo</tt> inside the vserver root):

# vmount guestname -- --bind /media/cdrom/foo /mnt/foo

|Question=How do I mount a device present on the host under a directory in a running guest?

||Details=Use something like:

vnamespace -e <guestname> mount -n /dev/<device> /vservers/<guest>/place/you/want/to/mount/it

This device can be unmounted with:

 

 

|Signature=derjohn/BenjaminGreen}}

 

|Question=Does anyone know how to increase the size of /tmp within a vserver w/o restarting?

||Details=Use the remount option for mount.

or something like that. The arguments are needed since mount is not going to be using /etc/fstab for the information and the version of /proc/mounts is best understood by

# vnamespace -e XID cat /proc/mounts.

See [[Frequently_Asked_Questions#I want to (re)mount a partition in a running guest ... but the guest has no rights (capability) to (re)mount?]]

 

 

 

<pre>/dev/drbd0    /      xfs    rw,dev          0 0</pre>

|Signature=AdrianReyer}}

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

/bin/sed --in-place -e "s/^\s\?session.*pam_limits.so.*/\#\0/g" /etc/pam.d/{su,sudo,cron}

This workaround allows you to have working <tt>pam_limits</tt> inside a guest system and global limits set by a host system. What's the catch? The problematic PAM module won't fully work for the root user on a guest system as expected and there might appear some PAM's warnings in guest's <tt>auth.log</tt>. Since using pam_limits to limit regular user processes is far more frequent than using it to limit root processes, this solution may be a good compromise. It is about setting a proper limits in pam_limits configuration and about setting this PAM module in a way that its function is optional (instead of required). The last change makes PAM to continue with session even if pam_limits encounters some error during setting limits (it usually applies to superuser sessions).

 

The not so nice news is that there might be a need of keeping guest's limits configuration up to date according to limits globally set for a guest. The limits set in pam_limits configuration file(s) shouldn't be higher (lower in case of nice value) than global guest's limits.

 

To apply it enter the guest and edit the files listed below, replacing occurences of <tt>required</tt> by <tt>optional</tt> in the lines containing <tt>pam_limits</tt>:

 

/etc/pam.d/su

/etc/pam.d/sudo

/etc/pam.d/cron

 

 

# through /etc/security/limits.conf

session      optional        pam_limits.so

 

Then on a guest system create the file <tt>/etc/security/limits.d/01-fixpam.conf</tt> containing:

*        -        priority        X  # replace X with your guest's nice value

You can automate this process to happen automagically for any guest by creating the startup script named <tt>/etc/vservers/.defaults/scripts/post-start.d/01-pamfix</tt>:

#!/bin/sh

 

 

PAM_DIR="etc/pam.d"

 

 

vcfg=$( /usr/sbin/vserver-info "$vname" CFGDIR )

 

        pamfile="${PAM_DIR#\/}/$s"

 

[ -n "$nval" ] && echo "* - priority $nval # (added by vserver startup script)" > "${LIMITS_FILE#\/}"

 

'''4. Disabling resource limits for a guest:'''

|Signature=Paweł Wilk}}

{{Question

|Question=How do I handle NFS mounts within in a guest?

||Details=There are at least four ways.

In any case, you probably want to force the nfs version to 3 or lower to avoid id mapping issues (one symptom of having an id mapping issue is that <tt>no_root_squash</tt> appears to be ignored). You can check whether the mount uses nfsv4 by looking at <tt>/proc/mounts</tt> inside the guest. You can force the protocol version to 3 by passing the mount options <tt>nfsvers=3,mountvers=3</tt>.

 

 

 

'''2)''' Use util-vserver and create a ''fstab.remote'' file in the /etc/vserver/<vserver_name> directory. Populate this with the NFS shares and they will be mounted in the context of the vserver guest.

 

 

Note that as of 0.30.216-pre3000 and kernel 3.0.4-vs2.3.1-pre10.1, the mount request will appear to originate from the IP of the host, not the guest. It is unclear (to [[User:KornAndras|Guy-]]) whether this is a bug.

 

'''3)''' Add capabilities to the vserver guest instance to grant sufficient rights to allow NFS mounts.

 

 

 

 

'''4)''' Before starting the guest, make a directory of the host "shared" using <tt>mount --make-shared /path/to/dir</tt>, then set up autofs to mount nfs shares under <tt>/path/to/dir/sharename</tt>.

 

 

 

 

 

|Question=vserver start/stop/enter fails with something like "vnamespace: execvp("/usr/sbin/vserver"): No such file or directory" ?

||Details=Check whether ''/usr'' is mounted in the namespace you are working with.

<pre>vnamespace -e <guest> mount /dev/<device> /usr</pre>

 

||Signature=sim0n}}

 

* use stable distribution of debian as server (debootstrap may be different over the versions)