Problem with new (P)ATA-CAM implementation: After update from 9.1 to 9.2 caused many kernel panics: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=193380#c14 It's gone after update to 10.1 and back again as cam issue after few security update (via freebsd-update): ada0:ata0:0:0:0): READ_DMA. ACB: c8 00 20 5a 5f 43 00 00 00 00 08 00 (ada0:ata0:0:0:0): CAM status: ATA Status Error (ada0:ata0:0:0:0): ATA status: 51 (DRDY SERV ERR), error: 40 (UNC ) (ada0:ata0:0:0:0): RES: 51 40 24 5a 5f 03 03 00 00 00 00 (ada0:ata0:0:0:0): Retrying command (ada0:ata0:0:0:0): READ_DMA. ACB: c8 00 20 5a 5f 43 00 00 00 00 08 00 (ada0:ata0:0:0:0): CAM status: ATA Status Error (ada0:ata0:0:0:0): ATA status: 51 (DRDY SERV ERR), error: 40 (UNC ) (ada0:ata0:0:0:0): RES: 51 40 24 5a 5f 03 03 00 00 00 00 (ada0:ata0:0:0:0): Retrying command (ada0:ata0:0:0:0): READ_DMA. ACB: c8 00 20 5a 5f 43 00 00 00 00 08 00 (ada0:ata0:0:0:0): CAM status: ATA Status Error (ada0:ata0:0:0:0): ATA status: 51 (DRDY SERV ERR), error: 40 (UNC ) (ada0:ata0:0:0:0): RES: 51 40 24 5a 5f 03 03 00 00 00 00 (ada0:ata0:0:0:0): Retrying command (ada0:ata0:0:0:0): Retrying command (ada0:ata0:0:0:0): READ_DMA. ACB: c8 00 20 5a 5f 43 00 00 00 00 08 00 (ada0:ata0:0:0:0): CAM status: ATA Status Error (ada0:ata0:0:0:0): ATA status: 51 (DRDY SERV ERR), error: 40 (UNC ) (ada0:ata0:0:0:0): RES: 51 40 24 5a 5f 03 03 00 00 00 00 (ada0:ata0:0:0:0): Error 5, Retries exhausted g_vfs_done():ada0s2a[READ(offset=7672586240, length=4096)]error = 5 Possible partially related with this bug: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=119838 Patch for ATA: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=199495