NFS4 share configuration in Ubuntu

Hi,

NFS is a service used to share a folder or a directory  located on one networked computer with other computers/devices on that network. It is a native Linux/ Unix protocol unlike samba, which can be shared both in windows and Linux

In NFS version 4 , there is a concept called pseudo file system.

That is there is a directory called /exports which is shared as pseudo file system and all of the directories in the server can be shared by binding it inside the /exports file system

/exports file system can be mounted using the command

mount -t nfs shareip:/ /mnt

That is there is no need to give the share name /exports on mounting it.

Also we can bind any directory inside the /exports folder and can be shared via nfs version4

Below is the steps to configure it

apt-get install nfs-kernel-server

Above command will install the required packages to run nfs server on ubuntu

In NFS 4 all of the directories we are going to share will exist inside a single pseudo file system

All of the directories can be shared under that pseudo file system using --bind option

Let's say we want to export our users' home directories in /home/users. First we create the export filesystem:

mkdir -p /export/users 

Now we will bind the /home/users directory inside the /export as

mount --bind /home/users /export/users
Also add it on /etc/fstab

/home/users /export/users none bind 0 0

Now open the configuration file /etc/exports and add the following shares as given below

/export 10.11.15.0/24(rw,fsid=0,insecure,no_subtree_check,async) /export/users 10.11.15.0/24(rw,nohide,insecure,no_subtree_check,async)

That is we are exporting the share to subnet 10.11.15.0/24
Once it is done we can start the nfs kernel service using the below command

# service nfs-kernel-server restart

On the client side install package called

apt-get install nfs-common

Once it is done try to mount the nfs share using the command below

mount -t nfs shareip:/ /mnt

mount -t nfs shareip:/users /mnt/users

Cheers
Syamkumar.M

Lustre Troubleshooting

Hi,

 Last Week, we faced an issue in which our KVM infrastructure, we are using lustre share for storing the disk images of VMs. We have few critical vms running in one of the nodes and those machines get into paused state showing that disk space is full on nodes

Exact error message is given below

"block I/O error in device 'drive-ide0-0-1': No space left on device (28)"

Upon checking the hard drive disk space inside that vm in single usermode, I can see that it had almost 2 TB of free space.

So I believe it was some issue with disk image. So I ran fsck on the disk image in single user mode. But still it didn't worked. Finally I confirmed that it was some issue with the lustre file system, when one more VM running from lustre getinto paused state with the same error.

Finally I began to trouble shoot for lustre errors. Below are the steps that I have done on debugging the lustre

I checked the lustre logs and found the error as


"(vvp_io.c:1018:vvp_io_commit_write()) Write page 369920 of inode ffff8820120601b8 failed -28".

On lustre documentation the error code -28 is "The file system is out-of-space or out of inodes"(http://wiki.lustre.org/manual/LustreManual20_HTML/LustreTroubleshooting.html)


Also I checked the command to list the disk space of all of the OSTs in lustre

lfs df -h 


UUID                       bytes        Used   Available Use% Mounted on
klust01-MDT0000_UUID        1.2T      933.1M        1.1T   0% /klust01[MDT:0]
klust01-OST0000_UUID        9.1T        8.6T      202.8M 100% /klust01[OST:0]
klust01-OST0001_UUID        9.1T        5.8T        2.8T  68% /klust01[OST:1]
klust01-OST0002_UUID        9.1T        5.5T        3.1T  64% /klust01[OST:2]
klust01-OST0003_UUID        9.1T        5.8T        2.9T  67% /klust01[OST:3]
klust01-OST0004_UUID        9.1T        6.5T        2.2T  75% /klust01[OST:4]
klust01-OST0005_UUID        9.1T        6.6T        2.0T  76% /klust01[OST:5]
klust01-OST0006_UUID        9.1T        7.9T      796.0G  91% /klust01[OST:6]
klust01-OST0007_UUID        9.1T        6.4T        2.2T  74% /klust01[OST:7]
klust01-OST0008_UUID        9.1T        6.8T        1.8T  79% /klust01[OST:8]
klust01-OST0009_UUID        9.1T        6.4T        2.2T  74% /klust01[OST:9]
klust01-OST000a_UUID        9.1T        8.6T       48.2M 100% /klust01[OST:10]
klust01-OST000b_UUID        9.1T        7.9T      733.8G  92% /klust01[OST:11]

filesystem summary:       109.1T       82.8T       20.8T  80% /klust01

In above the OST 0 and OST 10 is filledup to 100%.

On checking I can see that both the VM disks are located in OST10  whose disk is filled up.

Below is the command to check in which OST the image locates

lfs getstripe /var/test.img

lmm_stripe_count:   2
lmm_stripe_size:    1048576
lmm_stripe_offset:  8
    obdidx         objid        objid         group
         8           1815776         0x1bb4e0                 0
        10           1728679         0x1a60a7                 0

 So finally we deleted some unused data from ost 10 and then rebooted the OST main node, which fixed the issue.

Cheers 
Syamkumar M 
 
   

How to make a KVM Virtual machine boot From CDROM

Hi,

If you have a running KVM VM and you need to boot this VM from a Bootable Linux iso image inorder to fix some issues on the KVM machine. Below are the steps to boot the KVM machine from CD ROM.

KVM machine is using the xml files for the configuration. We need to edit the configuration xml file inorder to make any changes in the VM.

1_First Shutdown the VM using the command.

virsh shutdown vmname

2)Open the configuration file of the VM using the command

virsh edit vmname

3)Search for the word cdrom and add the lines as below

<disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/opt/isos/CentOS-6.3-x86_64-bin-DVD1.iso'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' unit='0'/>
    </disk>

Here we specified the iso image as the source file parameter.




4)Now the cdrom has been added on the VM. But now we need to make the cdrom as the first boot device.

For that we need to change the boot order of vm. Below is the lines which specifies the boot loader for the KVM vm


<os>
    <type arch='x86_64' machine='rhel6.2.0'>hvm</type>
<boot dev='cdrom'/>
<boot dev='hd'/>
    <bootmenu enable='yes'/>
  </os>





In above I put the boot device as cdrom in the parameter <boot dev='cdrom'/> and put it above the hd.

Now reboot the machine and then the vm will boot from the Linux iso image we added.

Cheers
Syamkumar

"Device eth0 does not seem to be present" After Cloning a Centos machine on Vsphere

Hi,

After cloning or moving a machine in VSphere, On starting the Virtual machine, I got error message as below

"Device eth0 does not seem to be present" Delaying initialization.

On cloning a Virtual machine on Vsphere, we need to edit the MAC adress on the VM settings. This change is recognized by the new VM . But it will list the NIC as eth1 instead of eth0, as eth0 MAC adress(Adress of the VM from which we cloned it) is still in the configuration file of new VM.

The configuration file where the Centos machine stores its NIC information is in

  vi /etc/udev/rules.d/70-persistent-net.rule

This file was automatically generated by the /lib/udev/write_net_rules
# program, run by the persistent-net-generator.rules rules file.
#
# You can modify it, as long as you keep each rule on a single
# line, and change only the value of the NAME= key.

# PCI device 0x15ad:0x07b0 (vmxnet3)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:0c:29:02:bf:b5", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

# PCI device 0x15ad:0x07b0 (vmxnet3)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:50:56:8b:2f:fd", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"


As you can see tat the new MAC Adress is recognized as the adress for eth1. So eth0 won't start.


so we need to edit that file and delete the first entry of in that file.


Then rename the eth1 to eth0  keeping only the second line.


After that start udev configuration using the command below


start_udev

Now restart network services:

service network restart

 

If there is proper configurations are set in the file /etc/sysconfig/network-scripts/ifcfg-eth0, then the eth0 will start.

Cheers

Syam

 

Error: Package: python-paramiko-1.7.6-1.el5.rf.noarch (rpmforge) Requires: python(abi) = 2.4

Hi,

 I had to install a package on a Centos 6.3 machine and I got python dependancy error as below.

Resolving Dependencies
--> Running transaction check
---> Package libedit.x86_64 0:2.11-4.20080712cvs.1.el6 will be updated
---> Package libedit.x86_64 0:20090923-3.0_1.el5.rf will be an update
---> Package libffi.x86_64 0:3.0.5-3.2.el6 will be updated
---> Package libffi.x86_64 0:3.0.9-1.el5.rf will be an update
---> Package perl-Test-Harness.x86_64 0:3.17-129.el6 will be updated
---> Package perl-Test-Harness.noarch 0:3.22-1.el5.rf will be an update
---> Package perl-Test-Simple.x86_64 0:0.92-129.el6 will be updated
---> Package perl-Test-Simple.noarch 0:0.98-1.el5.rf will be an update
---> Package portreserve.x86_64 0:0.0.4-9.el6 will be updated
---> Package portreserve.x86_64 0:0.0.5-2.el5.rf will be an update
---> Package python-beaker.noarch 0:1.3.1-6.el6 will be updated
---> Package python-beaker.noarch 0:1.5.3-1.el5.rf will be an update
--> Processing Dependency: python(abi) = 2.4 for package: python-beaker-1.5.3-1.el5.rf.noarch
---> Package python-mako.noarch 0:0.3.4-1.el6 will be updated
---> Package python-mako.noarch 0:0.3.5-1.el5.rf will be an update
--> Processing Dependency: python(abi) = 2.4 for package: python-mako-0.3.5-1.el5.rf.noarch
---> Package python-markupsafe.x86_64 0:0.9.2-4.el6 will be updated
---> Package python-markupsafe.x86_64 0:0.11-1.el5.rf will be an update
--> Processing Dependency: python(abi) = 2.4 for package: python-markupsafe-0.11-1.el5.rf.x86_64
---> Package python-paramiko.noarch 0:1.7.5-2.1.el6 will be updated
---> Package python-paramiko.noarch 0:1.7.6-1.el5.rf will be an update
--> Processing Dependency: python(abi) = 2.4 for package: python-paramiko-1.7.6-1.el5.rf.noarch
--> Finished Dependency Resolution
Error: Package: python-mako-0.3.5-1.el5.rf.noarch (rpmforge)
           Requires: python(abi) = 2.4
 Installed: python-2.6.6-36.el6.x86_64 (@anaconda-RedHatEnterpriseLinux-201301301459.x86_64/6.4)
               python(abi) = 2.6
           Available: python-2.6.5-3.el6.i686 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.5-3.el6_0.2.i686 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.6-20.el6.x86_64 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.6-29.el6.x86_64 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.6-29.el6_2.2.x86_64 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.6-29.el6_3.3.x86_64 (rhel-6-workstation-rpms)
               python(abi) = 2.6
Error: Package: python-paramiko-1.7.6-1.el5.rf.noarch (rpmforge)
           Requires: python(abi) = 2.4

 Installed: python-2.6.6-36.el6.x86_64 (@anaconda-RedHatEnterpriseLinux-201301301459.x86_64/6.4)
               python(abi) = 2.6
           Available: python-2.6.5-3.el6.i686 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.5-3.el6_0.2.i686 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.6-20.el6.x86_64 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.6-29.el6.x86_64 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.6-29.el6_2.2.x86_64 (rhel-6-workstation-rpms)
               python(abi) = 2.6
           Available: python-2.6.6-29.el6_3.3.x86_64 (rhel-6-workstation-rpms)
               python(abi) = 2.6
Error: Package: python-beaker-1.5.3-1.el5.rf.noarch (rpmforge)
           Requires: python(abi)

 Installed: python-2.6.6-36.el6.x86_64 (@anaconda-RedHatEnterpriseLinux-201301301459.x86_64/6.4)
               python(abi) = 2.6
     Available: python-2.6.5-3.el6.i686 (rhel-6-workstation-rpms)

The reason is that the python 2.6 package was installed by default on the Centos .But the new installation needs the python 2.4 . The best option is to install python-devel package for that.

So we can install it by enabling the EPEL repository in Centos. Below are the steps to enable EPEL repository in Centos

Enable EPEL Repository

wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
wget http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
sudo rpm -Uvh remi-release-6*.rpm epel-release-6*.rpm

Then do the following steps

yum clean all

yum clean metadata

Then install the required package. It will work

Cheers
Syam 

Reset Qmail Admin Postmaster Password

Hi All,


You need to login to Qmail Admin as postmaster inorder to control the email settings or to create new email accounts for the domain etc. But once you forget the password of postmaster account of the domain, you won't be able to manage the domain through the admin toaster.


Below is the step to reset the Admin password for the Qmail

1)First login to the Qmail server
2)Reset the password using the command as below

"/home/vpopmail/bin/vpasswd postmaster@testdomain.com"

change the password to new one. Now you will be able to login to the postmaster account with the new password.

Regards
Syamkumar

no iKVM64 in java.library.path on SuperMicro IP KVM

Hi All,


I faced an issue on accessing IPMI on  ubuntu 11.10. On launching java .jnlp file I am getting error message as below and got disconnected

"no iKVM64 in java.library.path on SuperMicro IP KVM"

A workaround for this problem is to download the .jnlp file and open it with an editor. Copy the two lines stated below, taken from the <resources> entry, to the corresponding <resources os=”Linux” arch=”amd64″> entry. Then start the file with java webstart.

<property name="jnlp.packEnabled" value="true"/>
<property name="jnlp.versionEnabled" value="true"/>