[ubuntu-cloud] Ubuntu HWE kernels on AWS?

Ben Howard ben.howard at canonical.com
Tue Jun 16 16:58:28 UTC 2015

The HWE kernels were originally targeted for hardware enablement. The
reason for suggesting that they are not viable for cloud use, is in
part, because of stability, support and virtual hardware was assumed to
be fairly static. However, we are seeing that the HWE kernels are quite
viable in cloud, that the assumption of static hypervisors was false,
and that people need newer kernel features on older userlands (Docker,
cgroups, file systems, etc).

By default GCE, Azure, and VMware Air, use the HWE enablement kernels at
the request of the Clouds. Incidentally, I am in the process of
releasing HWE builds for Trusty in the upstream images [1]. I expect to
have AWS EC2 image availability later this week.

The biggest problem with HWE kernels is that they have a shorter life
cycle (i.e. 14.04's hwe-{u,v,w} series will only live for 9 months). So
if you elect to use an HWE kernel, be aware that you may have to switch
off of it later to get bug fixes.

For 12.04, linux-image-generic-lts-trusty is supported for the remaining
life of 12.04. The generic kernel is -virtual with a larger set of
modules; it is fine to install on virtual targets.

For 14.04, linux-image-hwe-virtual-trusty will pull in the latest
supported hwe-kernel (and auto-upgrade you).


[1] https://cloud-images.ubuntu.com/trusty

On 06/16/2015 08:42 AM, Peter Wolanin wrote:
> Ubuntu offers package for 12.04 like linux-image-3.13.0-55-generic
> 3.13.0-55.92~precise1 that upgrade the kernel version.
> However, this wiki page says these kernels should not be used for
> Cloud deployments:
> https://wiki.ubuntu.com/Kernel/LTSEnablementStack
> I also note that there is no -virtual version of the kernel upgrade
> package.
> Is that note overly cautious, or are there real risks in trying to
> switch to the upgraded kernel?  We are motivated by fixes for xfs
> problems we are seeing when using the default 12.04 kernel on AWS.
> Thanks,
> -Peter
> -- 
> Peter M. Wolanin, Ph.D.      : Momentum Specialist,  Acquia. Inc.
> peter.wolanin at acquia.com <mailto:peter.wolanin at acquia.com> : 609-235-6869


Ben Howard
ben.howard at canonical.com
GPG ID 0x5406A866

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