I am struggling here. My end goal is assembling a RAID-6 array on my PC, but time and again, the assemble doesn't complete (and cat /proc/mdstat shows that one drive dropped away). This now happened with two separate drives.The issue is - I did various tests (rebooting Ubuntu, even going into Windows and formatting (not quick format) the drives/partitions there, and no issues were picked up with the drives).I suspect it's an issue on my Ubuntu installation but don't know where to start looking in log files etc.Some output below (11 drives -boot + 10 x 1TB drives)erwin@erwin-ubuntu:~$ sudo smartctl -i --scan/dev/sda -d scsi # /dev/sda, SCSI device/dev/sdb -d scsi # /dev/sdb, SCSI device/dev/sdc -d scsi # /dev/sdc, SCSI device/dev/sdd -d scsi # /dev/sdd, SCSI device/dev/sde -d scsi # /dev/sde, SCSI device/dev/sdf -d scsi # /dev/sdf, SCSI device/dev/sdg -d scsi # /dev/sdg, SCSI device/dev/sdh -d scsi # /dev/sdh, SCSI device/dev/sdi -d scsi # /dev/sdi, SCSI device/dev/sdj -d scsi # /dev/sdj, SCSI device/dev/sdk -d scsi # /dev/sdk, SCSI device/dev/sdl -d scsi # /dev/sdl, SCSI deviceThe issue is sdd and sdk (although they were available on boot), once I tried assembling on MDADM, after a few hours, a drive just drops out, and is no longer reported as available by either gparted or fdisk, etc.erwin@erwin-ubuntu:~$ sudo fdisk /dev/sddfdisk: unable to read /dev/sdd: Input/output errorCapture of a working driveerwin@erwin-ubuntu:~$ sudo smartctl -i /dev/sdbsmartctl 5.41 2011-06-09 r3365 [i686-linux-3.0.0-14-generic] (local build)Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net=== START OF INFORMATION SECTION ===Model Family:     Seagate Barracuda 7200.11Device Model:     ST31000340ASSerial Number:    9QJ0MD9FLU WWN Device Id: 5 000c50 00cca6f07Firmware Version: SD15User Capacity:    1,000,203,804,160 bytes [1.00 TB]Sector Size:      512 bytes logical/physicalDevice is:        In smartctl database [for details use: -P show]ATA Version is:   8ATA Standard is:  ATA-8-ACS revision 4Local Time is:    Sat Dec 17 10:59:13 2011 SASTCapture of the two problematic drives:erwin@erwin-ubuntu:~$ sudo smartctl -i /dev/sddsmartctl 5.41 2011-06-09 r3365 [i686-linux-3.0.0-14-generic] (local build)Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.netVendor:               /6:0:0:0Product:              User Capacity:        600,332,565,813,390,450 bytes [600 PB]Logical block size:   774843950 bytesscsiModePageOffset: response length too short, resp_len=47 offset=50 bd_len=46>> Terminate command early due to bad response to IEC mode pageA mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.erwin@erwin-ubuntu:~$ sudo smartctl -i /dev/sdhsmartctl 5.41 2011-06-09 r3365 [i686-linux-3.0.0-14-generic] (local build)Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.netVendor:               /11:0:0:Product:              0User Capacity:        600,332,565,813,390,450 bytes [600 PB]Logical block size:   774843950 bytesscsiModePageOffset: response length too short, resp_len=47 offset=50 bd_len=46>> Terminate command early due to bad response to IEC mode pageA mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.A command recommended on another forum, lsscsi:erwin@erwin-ubuntu:~$ lsscsi[0:0:0:0]    disk    ATA      ST3500630AS      3.AA  /dev/sda[2:0:0:0]    disk    ATA      ST31000340AS     SD15  /dev/sdb[3:0:0:0]    disk    ATA      ST31000528AS     CC38  /dev/sdc[6:0:0:0]    disk    ATA      ST31000340AS     SD15  /dev/sdd[7:0:0:0]    disk    ATA      ST31000528AS     CC36  /dev/sde[8:0:0:0]    disk    ATA      ST31000340AS     SD15  /dev/sdf[10:0:0:0]   disk    ATA      ST31000340AS     SD15  /dev/sdg[11:0:0:0]   disk    ATA      ST31000340AS     SD15  /dev/sdh[12:0:0:0]   disk    ATA      ST31000340AS     SD15  /dev/sdi[13:0:0:0]   disk    ATA      ST31000340AS     SD15  /dev/sdj[14:0:0:0]   disk    ATA      ST31000340AS     SD15  /dev/sdk[15:0:0:0]   disk    ATA      ST31000340AS     SD15  /dev/sdlWill post/edit details after reboot shortly..
Hard drives goes missing until reboot - what can be the cause?
hard disk;failure