Category Archives: Uncategorized

Linux run script/service after few mins of reboot

|

You can use systemd timers to execute script a minute after boot.

First, create service file (/etc/systemd/system/myscript.service):

[Unit]
Description=MyScript

[Service]
Type=simple
ExecStart=/usr/local/bin/myscript

Then create timer (/etc/systemd/system/myscript.timer):

[Unit]
Description=Runs myscript every hour

[Timer]
# Time to wait after booting before activation
OnBootSec=1min
Unit=myscript.service

[Install]
WantedBy=multi-user.target
Now enable and run it:

# systemctl enable myscript.timer
# systemctl start myscript.timer

.so: cannot open shared object file: Permission denied

|

When I start the application in debug mode (sh -x) it works fine after taking few seconds while loading the libraries but without debug mode it failes with .so : cannot open shared object file: Permission denied even though it has proper read permission as well as proper read permission to all parent folders.

Then I figured out that its due to selinux in enforcing state.

Change : /etc/selinux/config from SELINUX=enforcing ## or permissive to SELINUX=disabled

What is the difference between NIC Teaming and Bonding

|

NIC Teaming and NIC bonding are two different things.

NIC Teaming uses one of two methods, failover, and load-balancing with fail over. With a team you do not get a single 2gb connection (with two 1 gb NICs). You get two pipes that act as one, but merely are load balancing the traffic over each NIC, and each NIC acts as a fail over to the other. If you transfer a 100 gb file, you are not going to get 2gb of throughput…you still only get 1 gb, but you will not kill the network performance because the second NIC is still available to service other traffic.

True bonding would be taking two NICs and bonding them together to get a single fat pipe. This requires the switch to support this as well. I have not seen much bonding in the server world…more done at the network level.

VMWare acts the same way. It is purely load balancing and fail over. Since VMWare is done at the OS level, you can mix and match different vendor NICs in a team. I have done this without issue. Just make sure they are on the HCL.