Subject: ANNOUNCE: mdadm 3.3.4 - A tool for managing md Soft RAID under Linux I am somewhat disappointed to have to announce the availability of mdadm version 3.3.4 It is available at the usual places: http://www.kernel.org/pub/linux/utils/raid/mdadm/ and via git at git://github.com/neilbrown/mdadm git://neil.brown.name/mdadm http://git.neil.brown.name/git/mdadm.git In mdadm-3.3 a change was made to how IMSM (Intel Matrix Storage Manager) metadata was handled. Previously an IMSM array would only be assembled if it was attached to an IMSM controller. In 3.3 this was relaxed as there are circumstances where the controller is not properly detected. Unfortunately this has negative consequences which have only just come to light. If you have an IMSM RAID1 configured and then disable RAID in the BIOS, the metadata will remain on the devices. If you then install some other OS on one device and then install Linux on the other, Linux might eventually start noticing the IMSM metadata (depending a bit on whether mdadm is included in the initramfs) and might start up the RAID1. This could copy one device over the other, thus trashing one of the installations. Not good. So with this release IMSM arrays will only be assembled if attached to an IMSM controller, or if "--force" is given to --assemble, or if the environment variable IMSM_NO_PLATFORM is set (used primarily for testing). I strongly recommend upgrading to 3.3.4 if you are using 3.3 or later. NeilBrown 3rd August 2015.