I found the following workaround: as root:
echo "min_power" > /sys/class/scsi_host/host4/link_power_management_policy where host4 correspnds to my ata5 in the error message. Now the error messages have stopped. I hope this helps with debugging -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1318218 Title: SATA problems on MacBook Pro 11,1? Status in “linux” package in Ubuntu: Confirmed Bug description: I installed Ubuntu 14.04 next to MacOS following the guide at https://help.ubuntu.com/community/MacBookPro11-1/Saucy/ Looking into dmesg, I constantlz get entries like [ 276.380934] ata1: SError: { PHYRdyChg } [ 276.380943] ata1: hard resetting link [ 277.103527] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) [ 277.103999] ata1.00: unexpected _GTF length (8) [ 277.104504] ata1.00: unexpected _GTF length (8) [ 277.104507] ata1.00: configured for UDMA/33 [ 277.104629] ata1: EH complete [ 277.206319] ata1: exception Emask 0x10 SAct 0x0 SErr 0x10000 action 0xe frozen [ 277.206328] ata1: irq_stat 0x00400000, PHY RDY changed [ 277.206333] ata1: SError: { PHYRdyChg } [ 277.206343] ata1: hard resetting link [ 277.927757] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) [ 277.928425] ata1.00: unexpected _GTF length (8) [ 277.929040] ata1.00: unexpected _GTF length (8) [ 277.929051] ata1.00: configured for UDMA/33 [ 277.929168] ata1: EH complete [ 278.030944] ata1: exception Emask 0x10 SAct 0x0 SErr 0x10000 action 0xe frozen [ 278.030952] ata1: irq_stat 0x00400000, PHY RDY changed [ 278.030957] ata1: SError: { PHYRdyChg } [ 278.030965] ata1: hard resetting link [ 278.752008] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) [ 278.752582] ata1.00: unexpected _GTF length (8) [ 278.753140] ata1.00: unexpected _GTF length (8) [ 278.753147] ata1.00: configured for UDMA/33 [ 278.753231] ata1: EH complete [ 278.853417] ata1: exception Emask 0x10 SAct 0x0 SErr 0x10000 action 0xe frozen [ 278.853424] ata1: irq_stat 0x00400000, PHY RDY changed [ 278.853427] ata1: SError: { PHYRdyChg } [ 278.853434] ata1: hard resetting link [ 279.576258] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) [ 279.576881] ata1.00: unexpected _GTF length (8) [ 279.577417] ata1.00: unexpected _GTF length (8) [ 279.577427] ata1.00: configured for UDMA/33 [ 279.577491] ata1: EH complete [ 279.677753] ata1: exception Emask 0x10 SAct 0x0 SErr 0x10000 action 0xe frozen [ 279.677762] ata1: irq_stat 0x00400000, PHY RDY changed [ 279.677767] ata1: SError: { PHYRdyChg } [ 279.677776] ata1: hard resetting link [ 280.400449] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310) [ 280.401147] ata1.00: unexpected _GTF length (8) [ 280.401722] ata1.00: unexpected _GTF length (8) [ 280.401733] ata1.00: configured for UDMA/33 [ 280.401809] ata1: EH complete [ 280.502117] ata1: exception Emask 0x10 SAct 0x0 SErr 0x10000 action 0xe frozen [ 280.502127] ata1: irq_stat 0x00400000, PHY RDY changed [ 280.502132] ata1: SError: { PHYRdyChg } ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-24-generic 3.13.0-24.47 ProcVersionSignature: Ubuntu 3.13.0-24.47-generic 3.13.9 Uname: Linux 3.13.0-24-generic x86_64 NonfreeKernelModules: wl ApportVersion: 2.14.1-0ubuntu3 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: markus 1663 F.... pulseaudio /dev/snd/controlC1: markus 1663 F.... pulseaudio CurrentDesktop: Unity Date: Sat May 10 19:33:44 2014 HibernationDevice: RESUME=UUID=c71381d2-e2f3-4c96-94ea-57b8986afd08 InstallationDate: Installed on 2014-05-09 (0 days ago) InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417) MachineType: Apple Inc. MacBookPro11,1 ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-24-generic.efi.signed root=UUID=7584bc70-893a-4291-a1cb-4680f5e09d22 ro libata.force=noncq quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.13.0-24-generic N/A linux-backports-modules-3.13.0-24-generic N/A linux-firmware 1.127 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 10/29/2013 dmi.bios.vendor: Apple Inc. dmi.bios.version: MBP111.88Z.0138.B03.1310291227 dmi.board.asset.tag: Base Board Asset Tag# dmi.board.name: Mac-189A3D4F975D5FFC dmi.board.vendor: Apple Inc. dmi.board.version: MacBookPro11,1 dmi.chassis.type: 10 dmi.chassis.vendor: Apple Inc. dmi.chassis.version: Mac-189A3D4F975D5FFC dmi.modalias: dmi:bvnAppleInc.:bvrMBP111.88Z.0138.B03.1310291227:bd10/29/2013:svnAppleInc.:pnMacBookPro11,1:pvr1.0:rvnAppleInc.:rnMac-189A3D4F975D5FFC:rvrMacBookPro11,1:cvnAppleInc.:ct10:cvrMac-189A3D4F975D5FFC: dmi.product.name: MacBookPro11,1 dmi.product.version: 1.0 dmi.sys.vendor: Apple Inc. 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