This is a FreeBSD 9.1 amd64 computer. It has 5 disks installed. The ada0 and ada1 disks are used with a hw raid to provide the root filesystem: root@gw:/home/gandalf # ls /dev | grep ada ada0 ada1 ada2 ada3 ada4 root@gw:/home/gandalf # zpool status pool: zroot state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zroot ONLINE 0 0 0 raid/r0s1a ONLINE 0 0 0 errors: No known data errors I want to create a raidz pool for the remaining disks: root@gw:/home/gandalf # zpool create -f data raidz1 ada2 ada3 ada4 cannot create 'data': one or more devices is currently unavailable root@gw:/home/gandalf # dmesg | grep ada2 ada2 at ata4 bus 0 scbus6 target 0 lun 0 ada2: <WDC WD20EARS-00MVWB0 51.0AB51> ATA-8 SATA 2.x device ada2: 300.000MB/s transfers (SATA 2.x, UDMA5, PIO 8192bytes) ada2: 1907729MB (3907029168 512 byte sectors: 16H 63S/T 16383C) ada2: Previously was known as ad16 root@gw:/home/gandalf # dmesg | grep ada3 ada3 at ata5 bus 0 scbus7 target 0 lun 0 ada3: <SAMSUNG HD103UJ 1AA01118> ATA-7 SATA 2.x device ada3: 300.000MB/s transfers (SATA 2.x, UDMA5, PIO 8192bytes) ada3: 953868MB (1953523055 512 byte sectors: 16H 63S/T 16383C) ada3: Previously was known as ad18 GEOM_RAID: Intel-fb8732fa: Disk ada3 state changed from NONE to ACTIVE. GEOM_RAID: Intel-fb8732fa: Subdisk Volume0:0-ada3 state changed from NONE to ACTIVE. root@gw:/home/gandalf # dmesg | grep ada4 ada4 at ata6 bus 0 scbus8 target 0 lun 0 ada4: <TOSHIBA DT01ACA100 MS2OA750> ATA-8 SATA 3.x device ada4: 300.000MB/s transfers (SATA 2.x, UDMA5, PIO 8192bytes) ada4: 953869MB (1953525168 512 byte sectors: 16H 63S/T 16383C) ada4: Previously was known as ad20 root@gw:/home/gandalf # dmesg | grep GEOM_RAID Aha, so ada3 is already part of another raid volume? Let's see: root@gw:/home/gandalf # dmesg | grep GEOM_RAID GEOM_RAID: SiI-130628113902: Array SiI-130628113902 created. GEOM_RAID: SiI-130628113902: Disk ada0 state changed from NONE to ACTIVE. GEOM_RAID: SiI-130628113902: Subdisk SiI Raid1 Set:1-ada0 state changed from NONE to STALE. GEOM_RAID: SiI-130628113902: Disk ada1 state changed from NONE to ACTIVE. GEOM_RAID: SiI-130628113902: Subdisk SiI Raid1 Set:0-ada1 state changed from NONE to STALE. GEOM_RAID: SiI-130628113902: Array started. GEOM_RAID: SiI-130628113902: Subdisk SiI Raid1 Set:0-ada1 state changed from STALE to ACTIVE. GEOM_RAID: SiI-130628113902: Subdisk SiI Raid1 Set:1-ada0 state changed from STALE to RESYNC. GEOM_RAID: SiI-130628113902: Subdisk SiI Raid1 Set:1-ada0 rebuild start at 0. GEOM_RAID: SiI-130628113902: Volume SiI Raid1 Set state changed from STARTING to SUBOPTIMAL. GEOM_RAID: SiI-130628113902: Provider raid/r0 for volume SiI Raid1 Set created. GEOM_RAID: Intel-fb8732fa: Array Intel-fb8732fa created. GEOM_RAID: Intel-fb8732fa: Force array start due to timeout. GEOM_RAID: Intel-fb8732fa: Disk ada3 state changed from NONE to ACTIVE. GEOM_RAID: Intel-fb8732fa: Subdisk Volume0:0-ada3 state changed from NONE to ACTIVE. GEOM_RAID: Intel-fb8732fa: Array started. GEOM_RAID: Intel-fb8732fa: Volume Volume0 state changed from STARTING to DEGRADED. GEOM_RAID: Intel-fb8732fa: Provider raid/r1 for volume Volume0 created. root@gw:/home/gandalf # Yes, indeed. I want to get rid of raid/r1 completely. However, the controller was already set to "IDE" mode in the BIOS. So why it is creating a raid volume??? I have also tried overwritting the first 16k data of ada3 and reboot the computer, but it did not help. How can I delete /dev/raid/r1 ? root@gw:/home/gandalf # graid status Name Status Components raid/r0 SUBOPTIMAL ada0 (ACTIVE (RESYNC 4%)) ada1 (ACTIVE (ACTIVE)) raid/r1 DEGRADED ada3 (ACTIVE (ACTIVE)) root@gw:/home/gandalf # graid delete raid/r1 graid: Array 'raid/r1' not found. root@gw:/home/gandalf # graid delete /dev/raid/r1 graid: Array '/dev/raid/r1' not found. root@gw:/home/gandalf # Thanks