Hi everyone, I'm so happy to find this bug report, because it perfectly match my situation, even if I don't have SATA drives on my laptop, but I have indeed a SATA controller, and maybe this could be the key of the issue, and that's why I'm submitting my story. Almost an year ago a friend gave me a (quite) old Acer Aspire 5510 laptop, 2 Ghz Pentium M, Intel chipset and wireless, and Radeon X700. A perfect machine for Ubuntu, I thought. The controller is an Intel ICH6, and as far as I know it sports a SATA controller and a PATA one. (dmesg after the boot attached). The disk is a 100 GB Seagate PATA, and also the DVD burner is a PATA one but never worked well, it just (slowly) burn CD, and it does not burn nor mount DVD + or – R and RW. I use only linux at home, so I wiped out Windows, installing Ubuntu 8.04 Hardy (32 bits). The disk access was unbelievably slow starting from the boot, the light was always on with almost no flickering, and opening an application was a pain. The computer freezes a lot even if this slowness was not matched by hi cpu usage as it happens when no dma mode is set for the drive. The disk were just slow, no other symptoms. Having a SATA/PATA controller I've thought I've got a Libata/”combined mode” problem. I cannot set the bios because it's so locked down, but I've tried all kernel options related to this issues and many others, with no luck. Copying a file from and to the internal disk gave me a transfert rate of 2-4 MEGAbytes/s As other noticed in this thread, sometime (let's say once a month) I feel the computer faster at boot time, and eventually I get a decent trasfer 16-24 Mb/s but just for few minutes, then the situation reverts back to hell. Then came the Ibex. And the Ibex was better. Now I get trasfer stable at 8 Mb/s but it's still very slow (an old Athlon XP at 1400 Mhz I've here it's overall ways faster!) Actually stable is not the right word: it starts fast, then hangs, then gave me another burst, then another stop and so on during file copy. I've tried other distros, but them all suffer from the same issue. Again sometimes after the boot ( but less frequently then in Hardy) I get normal speed. If I copy from the internal disk to a USB drive the speed is a little faster (13 Mb/s) just because the disk is less stressed (it just read), but the system freezes anyway, and the internal disk light is stuck on. Comping from external usb disk to the same external disk gave me normal speed, greater then 20 Mb/S. This computer is almost unusable, I keep it just because I really want this issue solved, so I'm ready and willing to try everything you propose and give back any information you need. Thank you all, very much. Other infos on my current setup: uname -a Linux carlo-laptop 2.6.27-9-generic #1 SMP Thu Nov 20 21:57:00 UTC 2008 i686 GNU/Linux sudo hdparm -tT /dev/sda /dev/sda: Timing cached reads: 1688 MB in 2.00 seconds = 843.63 MB/sec Timing buffered disk reads: 86 MB in 3.02 seconds = 28.51 MB/sec /dev/sda: Model=ST9100822A , FwRev=3.01 , SerialNo= 3LG1CH85 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4 BuffType=unknown, BuffSize=8192kB, MaxMultSect=16, MultSect=?16? CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=195371568 IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5 AdvancedPM=yes: unknown setting WriteCache=enabled Drive conforms to: ATA/ATAPI-6 T13 1410D revision 2: ATA/ATAPI-1,2,3,4,5,6 * signifies the current active mode carlo@carlo-laptop:~$ sudo hdparm -i /dev/scd0 /dev/scd0: Model=Slimtype DVDRW SLW-831S , FwRev=WRS1 , SerialNo= Config={ Fixed Removeable DTR<=5Mbs DTR>10Mbs nonMagnetic } RawCHS=0/0/0, TrkSize=0, SectSize=0, ECCbytes=0 BuffType=unknown, BuffSize=0kB, MaxMultSect=0 (maybe): CurCHS=0/0/0, CurSects=0, LBA=yes, LBAsects=0 IORDY=yes, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 *udma2 AdvancedPM=no Drive conforms to: Unspecified: ATA/ATAPI-4,5,6,7 * signifies the current active mode carlo@carlo-laptop:~$ sudo hdparm -i /dev/scd0 /dev/scd0: Model=Slimtype DVDRW SLW-831S , FwRev=WRS1 , SerialNo= Config={ Fixed Removeable DTR<=5Mbs DTR>10Mbs nonMagnetic } RawCHS=0/0/0, TrkSize=0, SectSize=0, ECCbytes=0 BuffType=unknown, BuffSize=0kB, MaxMultSect=0 (maybe): CurCHS=0/0/0, CurSects=0, LBA=yes, LBAsects=0 IORDY=yes, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 *udma2 AdvancedPM=no Drive conforms to: Unspecified: ATA/ATAPI-4,5,6,7 * signifies the current active mode carlo@carlo-laptop:~$ lspci | grep IDE 00:1f.1 IDE interface: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) IDE Controller (rev 04)