Fwd: dmcache development
Ming Zhao
Xen 4.0.1 or Xen 4.1.1 (gitco.de builds) booted with dom0_mem=1024M
Kernel 2.6.18 or kernel 3.0 booted with pci=nomsi
iSCSI-link to a remote machine running 2.6.18
The iSCSI host exports a scsi device that the dom0 treats as an LVM PV.
The PV contains a VG with one LV per partition on each guest.
For the test-setup, I created a 128MB ramdisk (ramdisk_size=131072)
I used dmc-setup to bind the 10G lvm partition containing a
guest's root partition and /dev/ram0:
# ./dmc-setup.pl -o /dev/ivpsvg-001/tvps054root -c /dev/ram0 -n
tvps054cache -s 16384
Mounting the mapped device worked.
Reading and writing to the mapped device worked.
Next I changed the guest's configuration to use the mapped device:
# Generated by zero1 21093
name = "tvps054"
memory = 128
maxmem = 256
disk = [ 'phy:/dev/mapper/tvps054cache,xvda1,w',
'phy:/dev/mapper/ivpsvg--001-tvps054swap,xvda2,w' ]
vif = [ 'mac=00:16:3e:7d:6e:ba, bridge=xenbr300' ]
uuid = "7d6ebadc-4353-4c9e-828f-c8d5163360fb"
kernel = "/boot/vmlinuz-2.6.32.8-xls-xenu"
# ramdisk = ""
root = "/dev/xvda1 ro"
stdvga=0
vnc=0
apic=1
pae=1
vcpus = 1
on_reboot = 'destroy'
on_crash = 'restart'
It's the same configuration as the working one, with xvda1
being the only change.
After an 'xm create -c' of the domain, the domU kernel
initializes normally, up to:
NET: Registered protocol family 15
registered taskstats version 1
XENBUS: Device with no driver: device/console/0
Then the dom0 crashes, presumably because the domU starts
accessing the disk device.
I haven't set up a debugger yet, but I attached an old school
photograph of the kernel panic last time I managed to catch it.
Cheers,
Pim
