Comment 205 for bug 445852

Alain SAURAT (maisondouf) wrote :

I have a similar problem with an EeePC 701 ugraded with two SSD.

Originaly equiped with 4Gb SSD onto the mobo, Jaunty, Karmic and Lucid initialize it in UDMA66 mode without any problems and the read speed is around 30Mb/s.

I upgrade this notebook by adding a 32Gb PCIe PATA SSD in the extension connector.
BIOS well reconize them as Secondary Master for internal SSD and as Secondary Slave for PCIe SSD.

Now the kernel spend 3 timouts of 30 seconds to downgrade ata protocol from UDMA66 to PIO4 for the internal 4Gb SSD.
The PCIe SSD is directly use in UDMA66 mode.

After booting the read speed is 3Mb/s on internal SSD and 40Mb/s on PCIe SSD

I try, as I read here, to add "libata.dma=0" to the grub.cfg file, in this case timouts disapear but read speeds are very low on all disks

To avoid timouts and have a good read speed on /dev/sdb, can I deactivate UDMA mode only on /dev/sda and how ?

ps: I try an USB WinXP, there is no timout during boot and speeds are the sames ( Internal 4Mb/s, PCIe 40Mb/s )