Ordinarily I use “static” references in /etc/fstab to mount NFS shares to a server. Doing this on a Rocks Cluster however is a bit “hacky” and adapting every node can be automated by using rocks run host however there is a alternative way. (not sure if its better 😉 ) but Rocks uses Autofs to load NFS mounts when they are required. So I felt brave and wanted to learn something new. This is the documentation on that journey. 
On Centos 7.5 base install, there are no utility’s installed by default. So when I tried to mount an NFS share I got this error :
mount: wrong fs type, bad option, bad superblock on svennd.be:/data,
missing codepage or helper program, or other error
(for several filesystems (e.g. nfs, cifs) you might
need a /sbin/mount.<type> helper program)
In some cases useful info is found in syslog - try
dmesg | tail or so.
This clearly tells us it cannot communicate with the NFS share, fixing can be done installing : nfs-utils for Centos.
yum install nfs-utils
for Debian variants (Mint, Ubuntu, …) this would be :
apt install nfs-common
After that, I see happy shares 🙂
mount.nfs: timeout set for Wed Nov 14 12:57:50 2018 mount.nfs: trying text-based options 'soft,intr,retrans=2,rsize=32768,wsize=32768,nfsvers=3,tcp,addr=svennd.be' mount.nfs: prog 100003, trying vers=3, prot=6 mount.nfs: trying svennd.be prog 100003 vers 3 prot TCP port 2049 mount.nfs: prog 100005, trying vers=3, prot=6 mount.nfs: trying svennd.be prog 100005 vers 3 prot TCP port 20048 /data : successfully mounted
In a recovery of a system I found myself in annoying pickle of having two disks with a similar LVM layout and more precise with a equally named volume group. This can cause issues, however in my case it just stopped me from mounting the original device. To make matters worse the sizes of the volumes where nearly identically in size. Not really a user of LVM, it was time for google to save me.
Activating both identical volume failed :
[email protected]:~# vgchange -ay device-mapper: create ioctl on pve-swapLVM-Do7QVk4UeQXTTqVtB5b0pISJQy1YL1YJ4RB7lZXsAvYVGcYs9e7TZcFuHfkUBZJz failed: Device or resource busy device-mapper: create ioctl on pve-rootLVM-Do7QVk4UeQXTTqVtB5b0pISJQy1YL1YJgnTssDJJQj59LISgspFSLEH2pzqQLYw9 failed: Device or resource busy 1 logical volume(s) in volume group "pve" now active device-mapper: create ioctl on pve-dataLVM-46zXzJmc3xbdOtJdsVXrSlb5siaAacfRmhJ3Ac2ET7201zotB4DEX2kVu9gSafDC-tpool failed: Device or resource busy 2 logical volume(s) in volume group "pve" now active
So first thing I found was lvmdiskscan this will search for disk that are formatted with LVM. Not surprisingly I found two disks (new and old one) and a third data disk. (RAID)
[email protected]:~# lvmdiskscan /dev/sda2 [ 256.00 MiB] /dev/sda3 [ 465.51 GiB] LVM physical volume /dev/sdb2 [ 510.00 MiB] /dev/sdb3 [ 465.15 GiB] LVM physical volume /dev/sdc [ 29.10 TiB] 1 disk 2 partitions 0 LVM physical volume whole disks 2 LVM physical volumes
note : partition /dev/sda3 and /dev/sdb3 are dangerously similar !
Now we know that the partitions are very similar, however perhaps I might be lucky that the logical volumes where different lvscan :
[email protected]:~# lvscan inactive '/dev/pve/swap' [58.12 GiB] inherit inactive '/dev/pve/root' [96.00 GiB] inherit ACTIVE '/dev/pve/data' [295.03 GiB] inherit ACTIVE '/dev/pve/swap' [8.00 GiB] inherit ACTIVE '/dev/pve/root' [96.00 GiB] inherit inactive '/dev/pve/data' [338.60 GiB] inherit
note : there is a slight different in sizing of the volumes, this is good information. However the names are equal. This is causing the issue.
If we can change the volume group name (pve) this should be enough to mount it. However I don’t want to take the active ones, as that might crash my current system (?) So let’s check using vgdisplay :
[email protected]:~# vgdisplay --- Volume group --- VG Name pve System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 64 VG Access read/write VG Status resizable MAX LV 0 Cur LV 3 Open LV 0 Max PV 0 Cur PV 1 Act PV 1 VG Size 465.15 GiB PE Size 4.00 MiB Total PE 119078 Alloc PE / Size 114983 / 449.15 GiB Free PE / Size 4095 / 16.00 GiB VG UUID Do7QVk-4UeQ-XTTq-VtB5-b0pI-SJQy-1YL1YJ --- Volume group --- VG Name pve System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 7 VG Access read/write VG Status resizable MAX LV 0 Cur LV 3 Open LV 2 Max PV 0 Cur PV 1 Act PV 1 VG Size 465.51 GiB PE Size 4.00 MiB Total PE 119170 Alloc PE / Size 115075 / 449.51 GiB Free PE / Size 4095 / 16.00 GiB VG UUID 46zXzJ-mc3x-bdOt-JdsV-XrSl-b5si-aAacfR
Since there is a slight difference in size (449.51 vs 449.15) and I know the current disk in use is my new system (/dev/sda) (check using df -h).
I know I need /dev/sdb3 with 465.15 GB in size, this is the first in the list with UUID (Do7QVk-4UeQ-XTTq-VtB5-b0pI-SJQy-1YL1YJ)
Finally we know what we want to rename, it seems almost too simple using vgrename :
[email protected]:~# vgrename Do7QVk-4UeQ-XTTq-VtB5-b0pI-SJQy-1YL1YJ pveb Processing VG pve because of matching UUID Do7QVk-4UeQ-XTTq-VtB5-b0pI-SJQy-1YL1YJ Volume group "Do7QVk-4UeQ-XTTq-VtB5-b0pI-SJQy-1YL1YJ" successfully renamed to "pveb"
After this we can activate the volume group using vgchange :
vgchange -ay
And voila one can mount the new device :
mkdir -p /data/oldroot mkdir -p /data/data mount /dev/pveb/root /data/oldroot mount /dev/pveb/data /data/data
Tadaaa ! The data is available once more 🙂
We bought our first 10GBase-T switch. Pretty nice, but setting it up proved a bit more complex then our SuperMicro switches. Here I documented my search to get servers to talk to each other over a VLAN using the switch to assign IP addresses, using DHCP.
Login & Connect
Logging in proved rather easy and was similar to SuperMicro’s, connect “through the back” using a RJ45 alike cable that is actually a serial cable to USB. (I don’t think this was included, but there alternatives) Once connected I could find the “COM” port windows assigned checking Bluetooth devices :
One could also open the device manager and find it under COM ports. I used putty as my VT100 terminal emulator, on any Linux distro there are plenty of options but the easiest option would be screen. The setting of this switch are : 115200 baud speed, 8 data bits, 1 stop bits, none parity, none flow control.
Connect and enter twice and voila you can see the cli interface, the default login is “admin” and no password.
To get the assigned IP address :
# set ip ip management vlan 1 8.8.8.8 # get ip show ip management # or show ip vlan
After you get the IP address or guess it, you can go to the more simple web-interface configuration option. In my case the IP was 169.254.100.100. to be greeted with a login page.
Make VLAN
First I needed to make a VLAN, Switching -> VLAN -> basic -> VLAN Configuration. Giving a VLAN ID and a name (disable static). If everything works it should look like :
After this, you need to define the VLAN membership this can be done in Switching -> VLAN -> Advanced -> VLAN Membership. Go to VLAN ID you just made (in my case 400) and select group operation tag all then untag all, so that all ports show as untagged. (U).
From my basic understanding of VLAN’s and tagged packets, I figured that a port can only be part of one untagged VLAN. I’m probably wrong, but this “worked”. So I made all my ports that I intend to use for data to this new VLAN. Switching -> VLAN -> Advanced -> Port PVID Configuration. I changed VLAN member for all except my management port I’m using (1/0/1). Do this by entering the VLAN ID into VLAN Member and accepting the changes. It should look like :
Now for some reason, ports are still not able to communicate. Time to add a routing interface.
Routing Interface VLAN
This is totally new to me so, bare along : Routing -> VLAN -> VLAN Routing Configuration; We need to add routing configuration, from the dropdown select our PVID (400) and create a IP address for the routing (end with 1) I decided on 10.0.0.1 for the IP and subnet mask 255.255.255.0 so eventually IP’s allowed will be 10.0.0.[0-255].
It’s important to remember this IP adres, as we will re-use it once we setup the DHCP.
Setup DHCP service
Seamless next step, would you not say ? We need to setup the DHCP, which can be found : System -> Services -> DHCP Server -> DHCP Server Configuration.
We need to set the Admin Mode to enabled, and exclude our routing interface, so that this is not given out by the DHCP. It should look like :
After this we are ready to create the DHCP pool, do this under System -> Services -> DHCP Server -> DHCP Pool Configuration.
Pool name : (random) Type of Binding : Dynamic. Network Addressshould be the one we picked for the routing interface and excluded in the previous step. But instead of 1 use 0. In our case Network Address is 10.0.0.0 and the netmask is 255.255.255.0 or length 24. I setup lease time, to 7 days, which is a weekly thing. Should end up looking like :
After this the only thing remaining is testing & saving the configuration. If you are happy with how it works save your configuration. Maintenance -> Save Configuration
While updating our network on the Rocks Cluster, the nodes had to reinstall (this is default protocol). Now however the nodes got stuck during PXE (over the net automatic installation) on the setting of the language.
a screen like this (source).
This is annoying as it would mean connect a screen and a keyboard to every node to install. This however is an indication that something is wrong all together, however finding what proved a little bit tricky, that’s why I share it here.
To find if you face the same issue, execute :
sudo -u apache /opt/rocks/bin/rocks list host profile compute-0-0
This will show the configuration the node pulled from the head-node. In my case it looked like :
Traceback (most recent call last):
File "/opt/rocks/bin/rocks", line 301, in <module>
command.runWrapper(name, args[i:])
File
"/opt/rocks/lib/python2.6/site-packages/rocks/commands/__init__.py",
line 2194, in runWrapper
self.run(self._params, self._args)
File
"/opt/rocks/lib/python2.6/site-packages/rocks/commands/list/host/profile/__init__.py",
line 301, in run
for host in self.getHostnames(args):
File
"/opt/rocks/lib/python2.6/site-packages/rocks/commands/__init__.py",
line 773, in getHostnames
min,max = self.db.fetchone()
TypeError: 'NoneType' object is not iterable
While this should be a large XML file structure like. After allot of extensive google skills (and this 2013 topic) I found out that a simple MySQL update had dropped the root password out of the global configuration, this can be found :
/opt/rocks/etc/my.cnf
a update, generally saves it here :
/opt/rocks/etc/my.cnf.rpmsave
it should look like this :
[mysqld] user = rocksdb port = 40000 socket = /var/opt/rocks/mysql/mysql.sock datadir = /var/opt/rocks/mysql [client] user = rocksdb port = 40000 socket = /var/opt/rocks/mysql/mysql.sock password = <password>
You don’t have to restart the MySQL or the service, just let the node reboot and it will install properly 🙂
Good luck
Rocks distro is a cluster system. It comes with SNMP configured out of the box. It is polled using Ganglia. Which is working nicely, but I like to have all SNMP data in my favorite SNMP system, LibreNMS. Changing the SNMP configuration to be able to poll from LibreNMS should be a rather straight forward process, however those nodes have no connection to the public network. They have a private VLAN to talk to the head-node and a private VLAN to communicate with the storage array. So to get the SNMP data to Librenms we will have to get crafty with Iptables to get this data to LibreNMS on the public net.
Configuration
First let’s check the /etc/snmp/snmpd.conf file from the Rocks installation :
com2sec notConfigUser default public group notConfigGroup v1 notConfigUser group notConfigGroup v2c notConfigUser view all included .1 80 access notConfigGroup "" any noauth exact all all all
This config is a bit complex and I figure I won’t go back, so I commented it. I decided not to remove it completely, since I don’t want to break the possibility to go back to Ganglia should it be an important system in Rocks. (note : it’s not) I added :
# this create a SNMPv1/SNMPv2c community named "my_servers" # and restricts access to LAN adresses 192.168.0.0/16 (last two 0's are ranges) rocommunity my_servers <our_public_net>/16 rocommunity my_servers 10.1.0.0/16 # setup info syscontact "svennD" # open up agentAddress udp:161 # run as agentuser root # dont log connection from UDP: dontLogTCPWrappersConnects yes
Important here is, that I added two IP ranges, I’m not sure if the private VLAN (10.1.0.0/16) is even required, but since traffic is going over those devices I just added it.
Next thing is setting up the Iptables on the head-node. Since Rocks is already pretty protective (good !) I had to add an extra rule to even allow SNMP polling from the device :
-A INPUT -p udp -m udp --dport 161 -j ACCEPT
Allow the head-node to be polled by LibreNMS by accepting incoming UDP packets over port 161.
To receive packets send from the node on port 161 to the head-node, but forward this to port 3161 externally to LibreNMS (circumventing most known ports and the REJECT rule in Rocks for port 1-1023.) can be done with prerouting rule :
-A PREROUTING -i eth1 -p udp -m udp --dport 3161 -j DNAT --to-destination 10.1.255.244:161 -A POSTROUTING -o eth1 -j MASQUERADE
Note : 10.1.255.244 is the private IP of the node.
So from now on packets should come in, this can be checked using tcpdump, which came in handy during the debugging of this project : (on the node)
tcpdump 'port 161'
To be able to let snmpd answer we needed the information to be forwarded on the head-node, this can be done with a forward rule :
-A FORWARD -d 10.1.255.244/32 -p udp -m udp --dport 161 -m state --state NEW,RELATED,ESTABLISHED -j
note : again 10.1.255.244 is the ip of the node.
Surprisingly the node was unable to answer to the incoming requests. This was due to the fact that, the default route (route -n) was pointing towards one of the storage servers. To add a default gateway we can add it using route :
route add default gw 10.1.1.1 eth0
note : 10.1.1.1 is the private VLAN ip of the head-node.
Conclusion
Bam! LibreNMS can talk to the node using the public IP of the head-node on port 3161 and to the head-node on port 161. One issue that remains unsolved is on reboot, this setup is lost. Rocks by default will reinstall nodes that reboot. This can be resolved by adapting the configurations on Rocks and rebuild the distribution (rocks create distro). However this is rather advanced and (IMHO) difficult to debug. So I did not use that system for this project. Another problem is that its rather work-intense to add all the configuration to all the nodes. (this is only for a single node) This can be resolved most easily using scripts and using rocks run host to execute bits on all the nodes. I decided that I only want one node to be polled as a sample. I already track opengridscheduler using an extend on the head-node. So this is mostly for debugging. Good luck !
Oh noes, while starting a container, it failed cause of a corrupt quota file…
Starting container ... vzquota : (error) quota file is corrupted vzquota on failed [4] TASK ERROR: command 'vzctl start 114' failed: exit code 60
The fix is to remove it and rebuild it (this takes a long time, depending on the size of the container)
# this failed vzquota off 114 # delete the quota quota drop 114
We can rebuild the quota using vzquota but that is done automatically if you restart the container :
# vzctl start 114 Starting container ... Initializing quota ...
The vzquota currently running is : (for reference)
/usr/sbin/vzquota init 114 -b 8388608100 -B 9227468900 -i 1600000100 -I 1760000100 -p /data/private/114 -e 0 -n 0 -s 0
Sit back and relax, cause this will take time.
Got this error :
mount.nfs: rpc.statd is not running but is required for remote locking. mount.nfs: Either use '-o nolock' to keep locks local, or start statd. mount.nfs: an incorrect mount option was specified
You forgot the rpcbind service !
yum install rpcbind service rpcbind start chkconfig rpcbind on
Glad to help 😉
I’m a long time user of Proxmox (a few years), and recently I had the chance to upgrade an by-now ancient Proxmox 3.4 to current 5.2. In that time frame the developers have changed from OpenVZ to LXC and made a script to migrate the data. One key element however, mounting (remote) NFS shares are no longer possible from within the containers, at least not native.
Within the container the error is rather lacking information and is pointing towards the NFS server issue.
Aug 8 09:09:51 svennd mount: mount.nfs: access denied by server while mounting nfs_server:/data
However, on the Proxmox host, in /var/log/messages you can find that apparmor is the problem.
apparmor="DENIED" operation="mount" info="failed flags match" error=-13 profile="lxc-container-default-cgns" name="/storage/nfs_server/data/" pid=25086 comm="mount.nfs" fstype="nfs" srcname="nfs_server:/data" flags="ro, noatime"
It seems this is a feature 
.
Well now, lets try and undo this security feature, in my case the profile that is causing it to block is lxc-container-default-cgns. You can find this file : /etc/apparmor.d/lxc/lxc-default-cgns Also some other configs can be found there (not sure when what profile is loaded) I added :
mount fstype=rpc_pipefs, mount fstype=nfs,
below mount fstype=cgroup -> /sys/fs/cgroup/**, resulting in this final file :
# Do not load this file. Rather, load /etc/apparmor.d/lxc-containers, which
# will source all profiles under /etc/apparmor.d/lxc
profile lxc-container-default-cgns flags=(attach_disconnected,mediate_deleted) {
#include <abstractions/lxc/container-base>
# the container may never be allowed to mount devpts. If it does, it
# will remount the host's devpts. We could allow it to do it with
# the newinstance option (but, right now, we don't).
deny mount fstype=devpts,
mount fstype=cgroup -> /sys/fs/cgroup/**,
mount fstype=rpc_pipefs,
mount fstype=nfs,
}
After that we need to reload Apparmor, I’m not sure what made it work again, but it was one of these :
apparmor_parser -r /etc/apparmor.d/lxc-containers systemctl apparmor reload
And now we can mount from within once more ! 🙂
There is an alternative, but from what I read here you need to remap user ID’s, and need to use mountpoints on the host and draw them inside the container.
A small list for important Proxmox files & directories.
For LXC (Linux containers) :
config: /var/lib/lxc/$ct_id/config
For KVM (Kernel-based Virtual Machine, mostly Windows machines)
config: /etc/pve/qemu-server/$kvm_id.conf
Cluster files (if you use Proxmox cluster)
per node configuration : /etc/pve/nodes/$node_name/*
Location of the ISO files that can then be loaded from the web interface :
/var/lib/vz/template/iso/