Re: xm/xl block-detach issue

["Sébastien Riccio" <sr@swisscenter.com>]

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On 10.07.2011 20:19, Daniel Stodden wrote:
> Okay, that needs to get fixed, but I don't know where. In XCP that's 
> how it's exclusively done, because it's the most general approach.

My guess at the moment is that it might be a problem with blktap and vhd 
or, blktap and my kernel combo, or blktap and my kernel combo and vhd :)

The kernel i'm actually playing with is: 2.6.39.2-xen-stable + blktap, 
built over a debian squeeze like this:

git clone git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git 
linux_xen_2.6.39.x-stable
cd linux_xen_2.6.39.x-stable
git checkout -b stable/2.6.39.x origin/stable/2.6.39.x
git remote add daniel git://xenbits.xensource.com/people/dstodden/linux.git
git fetch daniel
git merge daniel/blktap/next-2.6.39
make menuconfig (removing useless stuff, activating the needed ones)
make bzImage -j9 ; make modules -j9 ; make modules_install
[ etc ... ]

Playing more with it this morning I managed to start a vm with a vhd 
file for the disk (after provisioning it with some files and reboots...) 
, with this config:

box# cat /cloud/data2/configs/vm1.test.cfg
bootloader = "/usr/bin/pygrub"
memory = 1024
name = "vm1"
vcpus = 4
#vif = [ 'ip=10.111.5.10, bridge=trunk0, vifname=vm1.0' ]
disk = [ 'tap2:vhd:/cloud/data2/machines/vm1.vhd,xvda,w' ]
root = "/dev/xvda1"
extra = "fastboot"
on_poweroff = 'destroy'
on_reboot = 'restart'
on_crash = 'restart'

vm1 is up and rocking

box# xl list
Name                                        ID   Mem VCPUs      State   
Time(s)
Domain-0                                     0  1024    16     
r-----      26.2
vm1                                          2  1024     4     
-b----       2.8

But now if I issue a ps -aux in the dom0, it displays some process then 
hangs the ps.
(that was not the case before I start vm1)

And if I try to list the attached block devices with xl:

box# xl block-list 2
Vdev  BE  handle state evt-ch ring-ref BE-path
Segmentation fault

(dmesg)
[ 1592.151122] xl[2292]: segfault at 0 ip 00007f7de314e6d2 sp 
00007fff610e30b0 error 4 in libc-2.11.2.so[7f7de3117000+158000]

but works if i try to list it with xm:

box# xm block-list 2
Vdev  BE handle state evt-ch ring-ref BE-path
51712  0    0     4      23     8     /local/domain/0/backend/vbd/2/51712



I'll try with something else than vhd to see if the same happens, but my 
goal is to use vhd's ...


> Can you check if it works with some normal disk? Check out modules, 
> install lvm2, make sure you have dm-linear loaded, etc... You were 
> running a custom kernel, right? You're probably just missing sth.

modules lists:

root@xen-blade15:~# lsmod
Module                  Size  Used by
blktap                 17941  8
ocfs2                 618206  1
quota_tree              7539  1 ocfs2
ocfs2_dlmfs            17331  1
ocfs2_stack_o2cb        3482  1
ocfs2_dlm             204671  1 ocfs2_stack_o2cb
ocfs2_nodemanager     186569  14 
ocfs2,ocfs2_dlmfs,ocfs2_stack_o2cb,ocfs2_dlm
ocfs2_stackglue         7437  3 ocfs2,ocfs2_dlmfs,ocfs2_stack_o2cb
dm_round_robin          2260  1
configfs               21658  2 ocfs2_nodemanager
crc32c                  2688  8
iscsi_tcp               8503  6
libiscsi_tcp           11604  1 iscsi_tcp
libiscsi               34844  2 iscsi_tcp,libiscsi_tcp
scsi_transport_iscsi    28673  3 iscsi_tcp,libiscsi
openvswitch_mod        71205  3
xenfs                   9815  1
xfs                   501098  1
ext2                   61369  1
sg                     27333  0
sr_mod                 14760  0
cdrom                  35494  1 sr_mod
xen_evtchn              4739  2
loop                   16002  0
tpm_tis                 7821  0
tpm                    10878  1 tpm_tis
i7core_edac            15891  0
tpm_bios                4921  1 tpm
dcdbas                  5416  0
edac_core              34483  1 i7core_edac
evdev                   9374  4
usb_storage            43361  0
thermal_sys            14045  0
pcspkr                  1779  0
acpi_processor          5423  0 [permanent]
button                  4199  0
usbhid                 34740  0
hid                    78436  1 usbhid
ext4                  255423  1
mbcache                 5434  2 ext2,ext4
jbd2                   48549  2 ocfs2,ext4
crc16                   1319  1 ext4
dm_multipath           16384  2 dm_round_robin
scsi_dh                 4876  1 dm_multipath
dm_mod                 63657  7 dm_multipath
sd_mod                 34293  6
crc_t10dif              1292  1 sd_mod
uhci_hcd               21828  0
megaraid_sas           70747  3
ehci_hcd               37665  0
scsi_mod              144719  9 
iscsi_tcp,libiscsi,scsi_transport_iscsi,sg,sr_mod,usb_storage,scsi_dh,sd_mod,megaraid_sas
usbcore               137744  5 usb_storage,usbhid,uhci_hcd,ehci_hcd
bnx2                   70964  0

My vhd storage is on an ocfs2 shared storage attached with multipath 
iscsi. I will try it on a local storage too to eliminate
that possible cause.

Thanks for your time Daniel.

Sébastien





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