Re: [Xen-devel] Xen 4.3 xl migrate " htree_dirblock_to_tree" on second host

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2014-02-04 at 15:32 +0000, Mike C. wrote:
> 
> On February 4, 2014 11:33:42 AM GMT, Ian Campbell <Ian.Campbell@xxxxxxxxxx> 
> wrote:
> >On Tue, 2014-02-04 at 02:45 +0000, Miguel Clara wrote:
> >> The wiki mentions "NBD" but if I got it right this means the storage
> >> is in "host1" and all ndb does is connect to that host, so the disk
> >is
> >> never copied to disk 2?
> >> 
> >> Am I correct to assume this?
> >
> >Yes. N is for network.
> >
> >> I have a host where what I need is to move it from host1 to host2, or
> >> reverse if needed, there's no problem stopping it first, but I guess
> >> this is not what the "migrate" command is used for!
> >> 
> >> And for guest where I do wan to keep a backup with remus, is shared
> >> storage still a must? the wiki http://wiki.xen.org/wiki/Remus states:
> >> 
> >> -> Shared storage is not required
> >> 
> >> But if "migrate" doesn't work how would remus?
> >
> >I think Remus with xend supports out of band storage synchronisation.
> >This has not yet been implemented for xl remus support.
> >
> 
> And would xl remus work if the disks are drdb 'backend' which in turn point 
> to LVM?

I don't know, CCing Shriram the maintainer.

> 
> Thanks
> 
> >> 
> >> Sorry for all the questions just trying to understand this better,
> >and
> >> there's really no documentation about:
> >> xl migrate and xl remus!
> >> 
> >> thanks
> >> 
> >> On Mon, Feb 3, 2014 at 3:09 PM, Mike C. <miguelmclara@xxxxxxxxx>
> >wrote:
> >> > Makes sense...
> >> >
> >> > Is there documentation about xl migrate and xl remus?
> >> >
> >> > Say I want to migrate a host but first pause it?
> >> >
> >> > I could also snapshot the lvm but that doesn't save the memory and
> >the
> >> > domain would have to be offline.
> >> >
> >> > So if I want to migrate but don't have shared storage, what's the
> >best
> >> > approach drdb?
> >> >
> >> > Thanks
> >> >
> >> >
> >> >
> >> > On February 3, 2014 10:17:04 AM GMT, Ian Campbell
> ><Ian.Campbell@xxxxxxxxxx>
> >> > wrote:
> >> >>
> >> >> On Sat, 2014-02-01 at 01:32 +0000, Miguel Clara wrote:
> >> >>>
> >> >>>  I'm testing live migration without shared storage (I use LVM at
> >both
> >> >>> sides)
> >> >>>
> >> >>>
> >> >>>  Issuing "xl migrate" worked nice and the machine was migrated to
> >the
> >> >>> second host
> >> >>>
> >> >>>  However I see this in the second host log:
> >> >>>
> >> >>>  [ 1502.563251] EXT4-fs error (device xvda1):
> >> >>>  htree_dirblock_to_tree:892: inode #136303: block 533250: comm
> >> >>>  run-parts: bad entry in directory: rec_len is smaller than
> >minimal -
> >> >>>  offset=0(0), inode=0, rec_len=0, name_len=0
> >> >>>  Jan 31 17:17:01 remus-test kernel: [ 1502.563251] EXT4-fs error
> >> >>>  (device xvda1): htree_dirblock_to_tree:892: inode #136303: block
> >> >>>  533250: comm run-parts: bad entry in directory: rec_len is
> >smaller
> >> >>>  than minimal - offset=0(0), inode=0, rec_len=0, name_len=0
> >> >>>
> >> >>>  I also get errors
> >> >>> like:
> >> >>>  -bash: /bin/ping: cannot execute binary file
> >> >>>
> >> >>>  Is this to be expect on using none shared storage?
> >> >>
> >> >>
> >> >> Yes. If the underlying disk is not the same device between both
> >hosts
> >> >> then all bets are off and all sorts of bad things will be happen.
> >Think
> >> >> about it -- what would you expect to happen to an OS if a disk
> >suddenly
> >> >> started returning completely different data to what was written to
> >it.
> >> >>
> >> >> What you have seen seems like a plausible outcome.
> >> >>
> >> >> Ian.
> >> >>
> >> >
> >> > --
> >> > Sent from my Android device with K-9 Mail. Please excuse my
> >brevity.
> 



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