Thanks, Klaus. I understand that it's not 100% safe way :)
Thanks again 30 марта 2010 г. 16:43 пользователь Klaus Espenlaub <[email protected] > написал: > Sergey Malykhin wrote: > >> Thanks, Nikolay, >> >> I meant that I hacked kernel a little to get information about file, data >> buffer, buffer size and offset in file. And it's ok. I'm only not sure that >> I'll have working backup if do it while VB is running. I understand that the >> best solution - suspend VB and copy, but it's less interestin, because I'll >> have pauses in VB work. >> > > Sorry to sound a little annoyed, but I really don't understand why adding a > little virtualization makes people think they're looking at something they > never did before. > > Creating a copy of the VDI file (no matter how smart is it done by > intercepting file writes and what not) is just like creating a sector-based > copy of a hard disk without knowledge of the running guest OS. Without > taking special measures (for most OSes I wouldn't know what to do actually) > there cannot be any guarantee that the resulting copy is consistent. Even > pausing a VM will not fundamentally change this, because the guest OS could > have unwritten changes in its filesystem cache, i.e. in RAM. It'll > frequently work without noticeable corruption, but it remains a "keep > fingers crossed" solution. > > The only safe ways to create backups are those which the guest OS is aware > of (file-based or guest OS based snapshotting like Nikolay suggested), or > completely shut down the guest OS. Using mechanisms like saving state in > VirtualBox would require backing up the VM state file as well. > > Klaus > > Sergey >> >> 2010/3/30 Nikolay Igotti <[email protected] <mailto: >> [email protected]>> >> >> >> Hi Sergey, >> >> Not sure what you mean by "I'm controlling write function to vdi >> file from kernel", but in general it's possible to use FS's (such as >> ZFS) snapshotting capability to take snapshots of live VMs image. >> OTOH to be 100% safe, I would pause VM, flush OS write buffers with >> 'sync', and then copy underlying .vdi. >> If you assume image to change insignificantly, maybe it would make >> sense to take snapshot once image stabilized, and only backup >> differences. >> >> Hope that'll help, >> Nikolay >> >> >> >> Sergey Malykhin пишет: >> >> Hello, >> >> I have VB running and want to make backup for vdi file. But I >> only need to have changed sectors. I'm controlling write >> function to vdi file from kernel. Can you please answer is it >> enough just copy it while VM is running or I need to suspend it? >> >> TIA >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> vbox-dev mailing list >> [email protected] <mailto:[email protected]> >> >> http://vbox.innotek.de/mailman/listinfo/vbox-dev >> >> >> >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> vbox-dev mailing list >> [email protected] >> http://vbox.innotek.de/mailman/listinfo/vbox-dev >> > > > -- > Dr. Klaus Espenlaub > Sun Microsystems GmbH > Werkstrasse 24 > 71384 Weinstadt > Germany > > ===================================================================== > Sitz der Gesellschaft: > Sun Microsystems GmbH, Sonnenallee 1, D-85551 Kirchheim-Heimstetten > Amtsgericht Muenchen: HRB 161028 > Geschaeftsfuehrer: Thomas Schroeder > ===================================================================== >
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