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VMware walks back ban on booting vSphere from SD cards or thumb drives

But in future won't certify servers that allow booting from removable media

Updated VMware has walked back its decision to end support for non-persistent removable storage as a boot medium for its vSphere suite.

Virtzilla deprecated the feature in the early 2021 release of vSphere 7 Update 3, and in September advised it would not be supported in future releases.

The company has now reversed that stance.

An updated knowledge base article dated April 28 states "VMware will continue supporting USB/SD card as a boot device through the vSphere.Next product release, including the update releases. Both installs and upgrades will be supported on USB/SD cards."

Why the U-turn, you very reasonably ask? The knowledge base article offers no reason. The Reg has requested a comment and we'll let you know should one arrive.

Whatever the reason, VMware appears to have changed course somewhat grudgingly. The article points out several times that booting from non-persistent media is a bad idea. If you must use USB media, the article states, use a solid state disk.

VMware has good reason to discourage booting from non-persistent media. vSphere 7.x creates four partitions, one of which – ESX-OSData – stores configuration and system state data. That role means the ESX-OSData partition sees a lot of read/write action, at high speed. Removable storage is not built to handle that much traffic and can also wear out faster than enterprise-grade devices. Instability is a likely consequence of both issues – yet stability is very much a virtue VMware extolls.

So while the next version of vSphere will allow boot from removable media, it will move the OSData partition to a persistent device.

vSphere releases are supported for up to six years, and the next vSphere will probably emerge in late 2022. So those who like to boot from non-persistent removable storage devices will still be able to do so for years to come – but may need legacy hardware to do so.

The Register offers that suggestion because the knowledge base article also states that VMware is "working very closely with all the major OEMs to ensure that future generations of server platforms do not support USB/SD card as a boot device."

Which seems a little odd, given vSphere is increasingly used in edge servers – an environment where devices may be hours away from the tender caress of a technician and the chance to boot from removable storage if all else fails could be useful. ®

UPDATE, 23:45 UTC, May 5th VMware has sent the following statement.

Based on customer feedback, VMware has made the decision to continue supporting USB/SD card through the next major release of VMware vSphere.

This decision should provide relief to customers who had already deployed servers where remediation would be expensive, but also those customers who made new server investments they planned to use for the next vSphere release.

Even though VMware will support customers using USB/SD card boot device through the next major release of vSphere, the company continues to recommend to its customers to have a plan to eventually migrate away from using such boot devices.

VMware has provided strict guidance to all server OEM partners to remove USB/SD card boot device options on future generation of platforms—which has garnered broad acceptance from partners. VMware will also stop certifying newer generation of platforms that contain the USB/SD card boot devices.

The last sentence is news - VMware had not previously said it will not certify servers that allow boot from non-persistent removable storage. Such servers will therefore be unsupported by VMware, a situation few customers can tolerate.

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