I reported this bug to linux-raid on March 27 and to linux-kernel a week later and had zero responses from either. In case my previous message was too long, here it is again in brief. Kernel 2.2.14 + raid-2.2.14-B1 as shipped with Red Hat 6.x. RAID5 across multiple SCSI disks. Spin down one disk with ioctl SCSI_IOCTL_STOP_UNIT to simulate error. Kernel logs md: bug in file raid5.c, line 659 ********************************** * <COMPLETE RAID STATE PRINTOUT> * ********************************** followed by complete lock up of all activity on /dev/md0, including any attempt to do raidhot{add,remove}. *Please* can someone comment/help? The reason I am using a disk spin down to simulate failure is that echo "scsi remove-single-device 0 0 1 0" > /proc/scsi/scsi doesn't work for me with kernel 2.2. The underlying write gives EBUSY which the kernel source says means the disk is busy. This worked fine for me (along with add-single-device) on kernel 2.0 with RAID 0.90. *Please* can someone help, even if only by saying "scsi remove-single-device works fine for me with 2.2" or "no it doesn't work for me either but I don't care"? This problem is preventing the upgrade to 2.2 of a number of Linux servers and has meant that I've had to bring a new large server into service without the benefit of RAID (since it needs kernel 2.2 for other reasons). --Malcolm -- Malcolm Beattie <[EMAIL PROTECTED]> Unix Systems Programmer Oxford University Computing Services