One week after receiving Microsoft's blessing, the open source Xen project has been slapped with a heavy dose of criticism from groups who charge the software isn't data center ready.
Xen has enjoyed a two-year run as the server virtualization darling of the open source set. The software for carving up servers into numerous partitions has been pitched as a cheaper, faster alternative to products from VMware and Microsoft. XenSource, a well-funded start-up, has been doing most of the Xen cheerleading for the Linux masses.
One of XenSource's major selling points, however, now appears to have faded. The company promised customers that its software would be bundled into the new versions of SuSE and Red Hat Linux. Not so.
"XenSource is not stable yet, it's not ready for the enterprise," Red Hat VP Alex Pinchev told ZDNet Australia. "We don't feel that XenSource is stable enough to address banking, telco or any other enterprise customer, so until we are comfortable, we will not release it."
Red Hat's Xen reversal comes just as Novell this month started pumping out SuSE Linux Enterprise Server 10 with XenSource inside.
Along with Red Hat, a prominent industry analyst recently expressed his doubts about Xen.
"Xen just isn’t ready today," wrote Gordon Haff of Illuminata in a research note.
Haff then listed four items lacking in Xen that Red Hat staff had highlighted to him as problems.
- 1. The new “credit scheduler” was just checked into the xen-unstable tree earlier this month. SLE10 shipped with two other schedulers (BVT and sEDF). According to this posting by Keir Fraser (one of the original developers of Xen): “With the new credit scheduler checked into the xen-unstable tree, I wouldn’t recommend to use either BVT or SEDF. They’re both buggy. The new scheduler is supported by us, automatically load balances on SMP systems, and has a simpler administrator interface. Once credit scheduler has demonstrated its stability we’ll most likely remove the other two schedulers."
- 2. The SLE10 installer is primarily just for SUSE guests at this point. “…for Windows you have to use the manual approach by editing config files and changing entries to boot from CD/HD.”
- 3. Performance profiling (xenoprof) is still in flux. e.g., it doesn’t save or restore performance counter state on context switching (so it’s difficult to profile performance within guest OSs).
- 4. According to Red Hat: “Xen security is an issue [that] Xen currently has no concept of: opening up the migration port, for example, will expose all of the guests to anybody on the network. (Imagine driving a server truck into a corporate parking lot, migrating all the instances to your servers, and driving off ;-).)”
"I’ve no reason to think any of this is Red Hat Xen bashing," Haff added. "I’ve had past conversations with Red Hat executives such as CTO Brian Stevens where they have been very supportive of Xen. Furthermore, the view of Xen as a work in progress is mirrored from a variety of sources—including a Novell engineer at their March Brainshare Conference where the best he could say about Xen stability was that it was 'A lot more stable than three months ago.' Sun, which also plans to incorporate Xen into Solaris, likewise views it as a technology for a future season—probably sometime in the first half of next year."
Not too long ago, it seemed that Xen could do no wrong. Everyone wanted a piece of this company that looked set to take Linux to the next level on the server without needing a proprietary friend like VMware to help.
But folks keeping a close eye on the server virtualization market will have noticed a major shift against Xen and XenSource in recent months.
For one, XenSource once made it sound like future versions of the Linux kernel would definitely embrace Xen's virtualization model and protocol preferences over rivals' products. In April, we learned that wasn't true, as the kernel leads are far from picking a server virtualization model of choice. In fact, the SWsoft crew recently told us that the company's OpenVZ project may well be the preferred server virtualization software found in Linux.
In addition, XenSource has moved to form strong ties with Microsoft of all companies in the hopes of rattling VMware. The Redmond love can't go unnoticed in the Red Hat boardroom.
Few would dispute the notion that customer interest in Xen remains high. But it would seem that the open source project has shifted out of its euphoric stage and into the fickle marketplace stage. ®