On Monday, Amazon wanted us to know that its staff worked day and night to avert planned reboots of cloud instances and updated a blog post to flag that information. But it didn’t provide any specifics on how these live updates were implemented.
Did [company]Amazon[/company] use live migration — a process in which the guest OS is moved to a new, safe host? Or did it use hot patching in which dynamic kernel updates are applied without screwing around with the underlying system?
Who knows? Because Amazon Web Services ain’t saying. Speculation is that it used live migration — even though AWS proponents last fall insisted that live migration per se would not have prevented the Xen-related reboots it launched at that time.
But where AWS remains quiet, [company]Google[/company], which wants to challenge AWS for public cloud workloads, was only too glad to blog about its live migration capabilities launched last year. Live migration, it claimed on Tuesday, prevented a meltdown during the Heartbleed vulnerability hullabaloo in April.
Google’s post is replete with charts and graphs and eight-by-ten glossies. Kidding about the last part but there are lots of diagrams.
A betting person might wager that Google is trying to tweak Amazon on this front by oversharing. You have to credit Google’s moxie here and its aspirations for live migration remain large. Per the Google Cloud Platform blog:
The goal of live migration is to keep hardware and software updated across all our data centers without restarting customers’ VMs. Many of these maintenance events are disruptive. They require us to reboot the host machine, which, in the absence of transparent maintenance, would mean impacting customers’ VMs.
But Google still has a long row to hoe. Last fall, when Google started deprecating an older cloud data center zone in Europe and launched a new one, there was no evidence of live migration. Customers were told to make a disk snapshots and use them to relaunch new VMs in the new zone.
As reported then, Google live migration moves working VMs between physical hosts within zones but not between them. Google promised changes there too, starting in late January 2015 but there appears to be nothing new on that front as yet.
So let the cloud games continue.