Hi!
I have installed 11.1 x64 with Xen to a Sun Fire X2200 M2 (QuadCore Opteron, NVidia MCP55Pro, two 500GB SATA drives, software mirror, only RAID1, no LVM)
While running the default kernel (without Xen) almost everything looks fine. (I always see the “boot.md failed” message during the system starts services, but all my RAID partitions are there, and the system runs)
If I start the Xen kernel, after 10-15 minutes the kernel starts to drop messages like this:
Jan 23 16:41:39 db1 kernel: ata1.00: qc timeout (cmd 0xa0)
Jan 23 16:41:39 db1 kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
Jan 23 16:41:39 db1 kernel: ata1.00: cmd a0/00:00:00:00:00/00:00:00:00:00/a0 tag 0
Jan 23 16:41:39 db1 kernel: cdb 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Jan 23 16:41:39 db1 kernel: res 51/20:03:00:00:00/00:00:00:00:00/a0 Emask 0x5 (timeout)
Jan 23 16:41:39 db1 kernel: ata1.00: status: { DRDY ERR }
Jan 23 16:41:44 db1 kernel: ata1: link is slow to respond, please be patient (ready=0)
Jan 23 16:41:49 db1 kernel: ata1: device not ready (errno=-16), forcing hardreset
Jan 23 16:41:49 db1 kernel: ata1: soft resetting link
Jan 23 16:41:49 db1 kernel: ata1: nv_mode_filter: 0x701f&0x701f->0x701f, BIOS=0x7000 (0xc0000000) ACPI=0x701f (60:900:0x11)
Jan 23 16:41:49 db1 kernel: ata1.00: configured for UDMA/33
Jan 23 16:41:49 db1 kernel: ata1: EH complete
Jan 23 16:41:54 db1 kernel: ata1.00: qc timeout (cmd 0xa0)
Jan 23 16:41:54 db1 kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
Jan 23 16:41:54 db1 kernel: ata1.00: cmd a0/00:00:00:00:00/00:00:00:00:00/a0 tag 0
Jan 23 16:41:54 db1 kernel: cdb 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Jan 23 16:41:54 db1 kernel: res 51/20:03:00:00:00/00:00:00:00:00/a0 Emask 0x5 (timeout)
Jan 23 16:41:54 db1 kernel: ata1.00: status: { DRDY ERR }
Jan 23 16:41:59 db1 kernel: ata1: link is slow to respond, please be patient (ready=0)
Jan 23 16:42:04 db1 kernel: ata1: device not ready (errno=-16), forcing hardreset
Jan 23 16:42:04 db1 kernel: ata1: soft resetting link
Jan 23 16:42:04 db1 kernel: ata1: nv_mode_filter: 0x701f&0x701f->0x701f, BIOS=0x7000 (0xc0000000) ACPI=0x701f (60:900:0x11)
Jan 23 16:42:04 db1 kernel: ata1.00: configured for UDMA/33
Jan 23 16:42:04 db1 kernel: ata1: EH complete
And the system keeps sending these messages (3-4 times per hour, sometimes even more) 
TBH I was unable to create any Virtual Machines, or manage them (from YAST console) but that is probably my fault.
Does this issue sound familiar to anyone?