[Xen-devel] inconsistent metadata of vhd file while live migration

[alice wan <wanjia19870902@xxxxxxxxx>]

hi all,

 

i have some doubt about live migration which may cause inconsistent metadata of vhd file between two tapdisk2 process.

 

given that vm migrates from host A to host B, which image is vhd file.

 

in host B, it first creates devices including starting tapdisk2 process, at this time, tapdisk2 will read some metadata of vhd file. then, it xc_restore

 

in host A, before it start last iteration(stop-and-copy phase), while xc_save's going, vhd file has been changed including metadata. So, in hostB tapdisk2 process doesn't read the

 

newest metadata of vhd file.

 

for tapdisk2, when it starts, it will read footer, header, bat of vhd file. especially bat structure, if it's inconsistent, it'll cause problem.

 

Maybe my doubt isn't a real problem, however, i hope someone to figure it out for me. thanks in advance.

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