Paypal believes a Linux grid can replace the mainframe. Just as I posted in a previous post, many major companies in various industries are embracing the strength, versatility and stability of Linux for their core applications.
Thompson supervises a payment system that operates on about 4,000 servers running Red Hat Linux in the same manner that eBay and Google conduct their business on top of a grid of Linux servers. “I have been pleasantly surprised at how much we’ve been able to do with this approach. It operates like a mainframe,” he said.
PayPal takes Red Hat Enterprise Linux and strips out all features unnecessary to its business, then adds proprietary extensions around security. Another virtue of the grid is that PayPal’s 800 engineers can all get a copy of that customized system on their development desktops, run tests on their raw software as they work, and develop to PayPal’s needs faster because they’re working in the target environment. That’s harder to do when the core of the data center consists of large Unix symmetrical multiprocessing boxes or mainframes. In neither case is it cheap to install duplicates for developers, he said.
PayPal “pays very close attention to the Linux kernel development process” lead by Linus Torvalds and the kernel maintainers because future capabilities are being debated and resolved through the process, he said.
PayPal has experimented with virtualization and is watching carefully developments in open source virtualization, still a young field. “One place we see the kernel process at work is in virtualization,” Thompson said. VMware’s ESX Server can run Linux, as can the open source Xen hypervisor; both work outside the Linux kernel but can be linked to its internal operations. A year ago, Torvalds approved the addition of a contributed Kernel Virtual Machine, which runs inside the kernel and makes use of the kernel’s own memory management and other functions.
“If we could fully virtualize our middle tier, that would be another step of cost advantage,” said Thompson. More fully virtualized data centers also would allow him to shift workloads across the grid, depending on time of day and traffic volumes, which would lead to additional savings.
Source: Information Week.