Wednesday, August 20, 2014

NFS mount errors with "clnt_create: RPC: Unknown host" for CentOS 6

When attempting to mount CentOS 6, my mount fails with
clnt_create: RPC: Unknown host

Diagnostic:
If we do a more thorough diagnostic, this is the issue
# showmount -e  
clnt_create: RPC: Unknown host  
# showmount -e localhost  
Export list for localhost:  
/export/my_data \* 

Resolution:

Taken from Redhat Site

Implement forward and reverse lookups (A records and CNAME records) in DNS and have the system point towards the DNS servers. Implement for both IPv4 and IPv6. If unable to resolve DNS issues, change the /etc/hosts file from this:

Change from 
::1          localhost localhost.localdomain localhost6 localhost6.localdomain6
To
::1          machine_hostname localhost localhost.localdomain localhost6 localhost6.localdomain6

Restart the NFS service and check on the showmount -e localhost and showmount -e and attempt to mount the share.

# service nfs restart  
# showmount -e localhost  
# showmount -e 

Tuesday, August 19, 2014

Ganglia – error collecting data (127.0.0.1:8652): fsockopen error: Connection refused

If you are having issues after installing Ganglia according to the Blog  Installing and Configuring Ganglia on CentOS 5.8, and if you are facing errors like Ganglia – error collecting data (127.0.0.1:8652): fsockopen error: Connection refused 

First thing do take a look at whether you have the necessary ganglia and rrdcached userid and group in your /etc/passwd and /etc/shadow. You should have something lines like thie

/etc/passwd
..... 
rrdcached:x:101:445:rrdcached:/var/rrdtool/rrdcached:/sbin/nologin
ganglia:x:102:446:Ganglia Monitoring System:/var/lib/ganglia:/sbin/nologin

At /etc/group
rrdcached:x:445:
ganglia:x:446:

Make sure your /var/lib/ganglia permission is
drwxr-xr-x 4 ganglia ganglia 4096 Aug 19 10:47 rrds

Or you can change permission if your permission is not correct
# chown -Rv ganglia.ganglia rrds

Sunday, August 17, 2014

Using iblinkinfo to report link infomation for all links in the fabric

The command iblinkinfo is a useful command to give a good overview of link information for all links in the fabric

[root@node-h00 ~]# iblinkinfo
CA: node-c27 HCA-1:
      0xxxxxxxxxxxxxxx     24    1[  ] ==( 4X          10.0 Gbps Active/ ..... 
CA: node-c26 HCA-1:
      0xyyyyyyyyyyyyyyy    22    1[  ] ==( 4X          10.0 Gbps Active/ ..... 
CA: node-c25 HCA-1:
      0xzzzzzzzzzzzzzzz     29    1[  ] ==( 4X          10.0 Gbps Active/ .....
CA: node-c24 HCA-1:
      0xaaaaaaaaaaaaaaa     28    1[  ] ==( 4X          10.0 Gbps Active/ .....
CA: node-c25 HCA-1:
      0xsssssssssssssss     27    1[  ] ==( 4X          10.0 Gbps Active/ .....
...................
...................
...................

Step 2: Print all information on each node on one single line
[root@node-h00 ~]# iblinkinfo -l 

0xaaaaaaaaaaaaaaaa "          node-c26 HCA-1"     22    1[  ] ==( 4X          10.0 Gbps Active/  LinkUp)==>  0xswitchfa     19   29[  ] "IBM HSSM" ( )
0xvvvvvvvvvvvvvvvv "          node-c25 HCA-1"     29    1[  ] ==( 4X          10.0 Gbps Active/  LinkUp)==>  0xswitchfa     19   28[  ] "IBM HSSM" ( )
0xbbbbbbbbbbbbbbbb "          node-c24 HCA-1"     28    1[  ] ==( 4X          10.0 Gbps Active/  LinkUp)==>  0xswitchfa     19   27[  ] "IBM HSSM" ( )
0xcccccccccccccccc "          node-c23 HCA-1"     27    1[  ] ==( 4X          10.0 Gbps Active/  LinkUp)==>  0xswitchfa     19   26[  ] "IBM HSSM" ( )
0xdddddddddddddddd "          node-c20 HCA-1"     26    1[  ] ==( 4X          10.0 Gbps Active/  LinkUp)==>  0xswitchfa     19   25[  ] "IBM HSSM" ( )
0xeeeeeeeeeeeeeeee "          node-c21 HCA-1"     23    1[  ] ==( 4X          10.0 Gbps Active/  LinkUp)==>  0xswitchfa     19   24[  ] "IBM HSSM" ( )

.....
.....
.....


Step 3: List Down Ports in the Fabric
[root@strawberry-h00 ~]# iblinkinfo -d

Switch: swswswswswswss IBM HSSM:
          19   16[  ] ==(                Down/Disabled)==>             [  ] "" ( )
          19   19[  ] ==(                Down/ Polling)==>             [  ] "" ( )
          19   23[  ] ==(                Down/ Polling)==>             [  ] "" ( )
          19   31[  ] ==(                Down/ Polling)==>             [  ] "" ( )
          19   32[  ] ==(                Down/ Polling)==>             [  ] "" ( )
          19   33[  ] ==(                Down/Disabled)==>             [  ] "" ( )
          19   34[  ] ==(                Down/Disabled)==>             [  ] "" ( )
          19   35[  ] ==(                Down/Disabled)==>             [  ] "" ( )
          19   36[  ] ==(                Down/Disabled)==>             [  ] "" ( )
Switch: swswswswswswswsw IBM HSSM:
          16   31[  ] ==(                Down/ Polling)==>             [  ] "" ( )
          16   32[  ] ==(                Down/ Polling)==>             [  ] "" ( )
          16   33[  ] ==(                Down/Disabled)==>             [  ] "" ( )
          16   34[  ] ==(                Down/Disabled)==>             [  ] "" ( )
          16   35[  ] ==(                Down/Disabled)==>             [  ] "" ( )
          16   36[  ] ==(                Down/Disabled)==>             [  ] "" ( )


For all information:
  1. iblinkinfo(8) - Linux man page  

Friday, August 15, 2014

Create export domain or ISO Domain on RHEV 3

This is taken from Red Hat Portal How to create an export domain or iso domain? (Need customer access) On the NFS, you need to do the following
# mkdir /export/data
# chown -R 36:36 /export/data
# chmod 755 /export/data
# vim /export_data
/export/data *(rw)
# /etc/init.d/nfs restart
# chkconfig nfs on
The key setup is that the ownership must be given vdsm kvm (36:36). Or you will have errors like "Error while executing action Add Storage Connection: Problem while trying to mount target"
# mkdir /export/ISO 
# chown -R 36:36 /export/ISO 
# chmod 755 /export/ISO 
# vim /export/ISO /export/ISO *(rw) 
# /etc/init.d/nfs restart 
# chkconfig nfs on
References:
  1. Red Hat Enterprise Virtualisation and NFS (NetApp Community)
  2. How to create an export domain or iso domain? (Red Hat Portal - Restricted Access)

Wednesday, August 13, 2014

Subscribing to Red Hat Virtualisation Manager Channels

Taken from Red Hat Red Hat Enterprise Visualization Documentation Step 1: Register the system with Subscription Manager Run the following command and enter your Red Hat Network user name and password to register the system with the Red Hat Network
subscription-manager register
Step 2: Identify Available Entitlement Pools Entitlement pools containing the channels required to install the Red Hat Enterprise Virtualization Manager
# subscription-manager list --available | grep -A8 "Red Hat Enterprise Linux Server"
# subscription-manager list --available | grep -A8 "Red Hat Enterprise Virtualization"
Step 3: Attach Entitlement Pools to the System Use the pool identifiers located in the previous step to attach the Red Hat Enterprise Linux Server and Red Hat Enterprise Virtualization entitlements to the system. Run the following command to attach the entitlements:
# subscription-manager attach --pool=[POOLID]
Step 4: Enable the Required Channels Run the following commands to enable the channels required to install Red Hat Enterprise Virtualization:
# yum-config-manager --enable rhel-6-server-rpms
# yum-config-manager --enable rhel-6-server-supplementary-rpms
# yum-config-manager --enable rhel-6-server-rhevm-3.4-rpms
# yum-config-manager --enable jb-eap-6-for-rhel-6-server-rpms