Hi, The entire OS I am using is running on software RAID-1. Before killing the power of the UPS, I issue: /sbin/mdadm --readonly $RAIDDEV on all the RAID devices I have. This, however, does not seem to be enough, and when i power the system back on, the RAID arrays are not clean, and a long syncing starts. A last step is missing; something like marking the arrays that they are clean. I see this happening for a flash of a second when i tell the PC to "/sbin/poweroff", i.e. "halt -p". The very last second, before the ATX power is turned OFF, the kernel does something to the md arrays. My questions are: 1. What exactly is this last step? 2. Can I achieve it manually by sth like echo *** > /proc/*** or by using mdadm? Cheers Gaspar