Go Rebootless on Linux with Ksplice

When a Linux kernel updates, a reboot is required to apply the changes as you

have to boot with the new kernel features. And in cases when the system happens

to be a server, rebooting becomes painful as it contributes to the downtime of

the system. Again when you have customer SLAs where you have to stick to 5 nines

or 7 nines, this small little upgrade can cause you face tremendous pressure. At

the same time security updates or even for that matter any kernel update is not

something you can afford to ignore.

Ksplice converts the updates into hot updates which are prepared at object

code level instead of source code level, thus minimizing programmer's

involvement. Existing practices of updating Kernel rely on programmer writing a

source code files for changing certain properties or require a manual inspection

of running binaries to ensure safety guarantees. Ksplice, however, updates the

legacy binaries based on existing information (a source code patch) and so it

doesn't require a system reboot.

Ksplice replaces the whole function if any part of the code in the function

is to be modified by applying patch. It links the function to its newer

replacement code into the Kernel by placing a jump instruction which redirects

the path to replacement code. Also ksplice while applying an update the system

disrupts for 0.7 milliseconds; however no network connections or any open

application is affected. A small amount of memory is used in storing replacement

code. The software verifies the safety of updates before installing them. An

alternative to reduce downtime is Ksplice. To give it a try, you can download

the 30-day trial version for your Linux distribution (if you are using Ubuntu

9.04 or Ubuntu 9.10, then a free version is also available with graphical

manager). You will get an access key on registering with Ksplice on your email

Id. Just follow these easy steps.

Get an access key by signing up with Ksplice Uptrack and download it on your

system. To install, just click on the download link on the page and install it.

To install the package type this:

#rpm —i ksplice-uptrack-release.noarch.rpm

and then give the command to



install:

#yum install uptrack

Once installed, just edit /etc/uptrack/uptrack.conf using vi or vim and set

auto install to Yes.

Run Ksplice Uptrack. For this, just log in as root (Uptrack can be used only

when you are logged in as root). Go to command line and you can run the service

using this command:

#uptrack upgrade —y

After that all updates will start installing and after all updates are

installed, a message is displayed 'your kernel is up to date' . You can see all

the installed updates/ patches by using command:

#uptrack —show

You can uninstall the updates using command:

uptrack -remove id

and if you want to remove all updates type this:

uptrack -remove —all.

Ksplice can work on both virtual machines (both hosts and guests) securely.

It works fine with VMWare, Xen, Virtuozzo  and other virtualized

environments. Another feature of Ksplice is that all updates are

cryptographically signed and minimum information is sent to ensure safety, plus

any errors on your OS are reported that may occur during updates installation.

You will also get information on your email ID each time a new patch is

released.