Redhat satellite or Spacewalk – real time push to clients.

By default, a client waits for a set of interval (minutes) configured in /etc/sysconfig/rhn/rhnsd to pull scheduled tasks from satellite server. For instance, if a remote command is set to be executed on client or a patch is waiting to be applied, rhn_check has to wait at least for 60 minutes to pick up the task.

For real time command execution or patch or configuration deployment, the following steps have to be performed on server and client –

1. Server : Install osa-dispatcher

root:homevm:~:# rpm -q osa-dispatcher
osa-dispatcher-5.11.43-1.el6.noarch

root:homevm:~:# service osa-dispatcher status

root:homevm:~:# chkconfig osa-dispatcher on

root:homevm:~:# chkconfig osa-dispatcher --list
osa-dispatcher  0:off   1:off   2:on    3:on    4:on    5:on    6:off

2. Client : Install and enable osad (OSA daemon).

# yum install osad -y
# chkconfig osad on
# /etc/init.d/osad restart

3. Client : Make sure the deploy and run options are enabled –

# rhn-actions-control --enable-run
# rhn-actions-control --enable-deploy

# rhn-actions-control --report
deploy is enabled
diff is enabled
upload is enabled
mtime_upload is enabled
run is enabled

Extra steps in case you encounter SSL certificate issues –
OSA is picky on SSL certificte verification, make sure the right CA cert is deployed on client, and the serverURL on up2date should match with the CN on the server certificate.

1. Copy RHN certificate from satellite server to client, make sure the cert has not expired and the CN matches server name.

root:homevm:~:# openssl x509 -in /var/www/html/pub/RHN-ORG-TRUSTED-SSL-CERT -noout -subject
subject= /C=US/ST=CA/L=SanFrancisco/O=home.net/OU=spacewalk.home.net/CN=homevm.home.net

root:homevm:~:# openssl x509 -in /var/www/html/pub/RHN-ORG-TRUSTED-SSL-CERT -noout -dates
notBefore=Aug  2 06:04:05 2014 GMT
notAfter=Jul 27 06:04:05 2036 GMT

root:homevm:~:# scp /var/www/html/pub/RHN-ORG-TRUSTED-SSL-CERT root@client:/usr/share/rhn/RHN-ORG-TRUSTED-SSL-CERT

[root@blackhat rpm-gpg]# grep -i serverurl /etc/sysconfig/rhn/up2date 
serverURL=http://homevm.home.net/XMLRPC

2. If you get certificate error, during package deployment, copy the RPM GPG public keys from satellite to the clients
On Server side –

root:homevm:/etc/pki/rpm-gpg:# ls -al RPM-GPG-KEY-*
-rw-r--r-- 1 root root 1706 Nov 30  2013 RPM-GPG-KEY-CentOS-6
-rw-r--r-- 1 root root 1730 Nov 30  2013 RPM-GPG-KEY-CentOS-Debug-6
-rw-r--r-- 1 root root 1730 Nov 30  2013 RPM-GPG-KEY-CentOS-Security-6
-rw-r--r-- 1 root root 1734 Nov 30  2013 RPM-GPG-KEY-CentOS-Testing-6
-rw-r--r-- 1 root root 1649 Nov  4  2012 RPM-GPG-KEY-EPEL-6
-rw-r--r-- 1 root root 1011 Feb  5  2011 RPM-GPG-KEY-oracle

root:homevm:/etc/pki/rpm-gpg:# scp RPM-GPG-KEY-* root@client:/etc/pki/rpm-gpg

On client side -
[bash]
# rpm --import RPM-GPG-KEY-CentOS-*

References –
https://access.redhat.com/documentation/en-US/Red_Hat_Network_Satellite/5.3/html/Installation_Guide/s1-maintenance-push-clients.html

Reduce or shrink the size of non root LVM mount.

In a system with limited disk size, you might run out of disk space in one LVM mount while having plenty of space in another mount. If both LVMs are in the same volume group (VGs), you can easily take away some of the free space from one LVM and add it to the one with low disk space. Both lvreduce and lvresize commands can be used to shrink the LVM. In this example, we will use lvresize.

Note – the steps below have to be done with care, there is a potential for losing data. If the data in the existing partition is critical, make sure you take a backup.

Shrink LVM by example – we will reduce the LVM for /usr/local file system mount from 2.0G to approximately 1.5G.

1. Unmount partition after confirming no file is in use from the partition.

root:homevm:~:# df -Pvh /usr/local
/dev/mapper/vg00-lvol04  2.0G   68M  1.9G   4% /usr/local

root:homevm:~:# lsof /dev/mapper/vg00-lvol04 

root:homevm:~:# umount /usr/local/

2. Do a file system consistency check –

root:homevm:~:# e2fsck -f /dev/mapper/vg00-lvol04 
e2fsck 1.41.12 (17-May-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/mapper/vg00-lvol04: 46/131072 files (0.0% non-contiguous), 25423/524288 blocks

3. Reduce the file system first, so that the logical volume is always at least as large as the file system expects it to be.

root:homevm:~:# resize2fs /dev/mapper/vg00-lvol04 1400M
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/vg00-lvol04 to 358400 (4k) blocks.
The filesystem on /dev/mapper/vg00-lvol04 is now 358400 blocks long.

root:homevm:~:# mount /usr/local/

root:homevm:~:# lvresize -L 1500M /dev/mapper/vg00-lvol04 
  Rounding size to boundary between physical extents: 1.47 GiB
  WARNING: Reducing active and open logical volume to 1.47 GiB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lvol04? [y/n]: y
  Reducing logical volume lvol04 to 1.47 GiB
  Logical volume lvol04 successfully resized

root:homevm:~:# resize2fs /dev/mapper/vg00-lvol04 
resize2fs /dev/mapper/vg00-lvol04
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/vg00-lvol04 is mounted on /usr/local; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/mapper/vg00-lvol04 to 385024 (4k) blocks.
The filesystem on /dev/mapper/vg00-lvol04 is now 385024 blocks long.

root:homevm:~:# df -Pvh /usr/local
/dev/mapper/vg00-lvol04  1.5G   68M  1.4G   5% /usr/local

References –
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/Logical_Volume_Manager_Administration/