[clug] Seeking FOSS Hypervisor and Management GUI

[George at Clug]

    Bob,

1) Do you know how a Linux server can prepare for UPS shutdown by
stopping services and then changing the mount of the root partition to
be read only ?  This is something I have yet to find the time to
investigate but understand what should be implemented by the UPS
shutdown process.


2) With regards to your statement "I was thinking of just
backing-up/copying the system area";

With MS Windows, I would never have tried to backup just Windows
System area and hope to get the server to ever reboot again, however I
understand that this is actually possible with Linux (not that I yet
know how).

What would need to be backed up (not including /home if this is where
the data is), and can it be restored to a live system?  (I guess this
is documented somewhere in the Internet)
(my quick suggestion of what would need to be backed up  for MySQL,
DoveCot, Postfix, Samba?).
/etc
/var/
/bin
/sbin
/selinux
/proc
/lib
/lib64

Does the broken server's drive need to be mounted in another server
and then the files restored across the existing, broken server? Or if
the server is actually running, can services be stopped and the files
be restored.



At Wednesday, 01-10-2014 on 14:32 Bob Edwards wrote:


On 01/10/14 13:32, George at Clug wrote:
>      I really hate showing my ignorance, I had to look up what
dd was;
> The dd command copies a file, converting [1] the format of the data
in
> the process, according to the operands [2] specified.
>
> Snapshots have an advantage over "copies" of a virtual machine,
> especially when that virtual machine is a data repository that is
> larger than the free space (even when compressed) on the host
> hypervisor. And 6TB of data takes a while to copy, dd, etc.  A
> snapshot should just fork any new changes to the original image for
> the life of the snapshot, consolidation is the process of merging
the
> snapshot changes back into the original image.  If the snapshot is
> not too old, both of these tasks are usually are very quick.  At
> least that is how I understand the VM snapshot process.
>

That's all true.

I was thinking of just backing-up/copying the system area, not the
entire data repository, which should be backed up elsewhere. I suppose
the updates you want to apply might break the data repository, in
which case you could restore it from backup. But that would take
very many hours...

Cheers,

Bob Edwards.

> http://www.computerhope.com/unix/dd.htm
>
>
> Create a ISO disc image [3] from the CD in the computer.
>
>
> dd if=/dev/sr0 of=/home/hope/exampleCD.iso bs=2048 conv=noerror,sync
>
> To be honest most of my VMs range from 500GB to 3TB, but could grow
to
> 9TB quite easily, so I like to have a solution that can support into
> the future.
>
> Thank you for your comments. An old saying that I rather like is
> "_there is more than one way to skin a cat_", even if I am a cat
lover
> who believes the best way is "not to skin a cat at all".
>
>
>
>
>
>   Of course, "snapshots", as you are wanting to use them, are just
a
> "convenience".
>
> You can almost as easily just shutdown your VM when it is good, run
dd
> etc. into gzip to get a copy of the VM disk image, then start it
back
> up and go ahead and break it.
>
> When you want the original back, just gunzip and dd the saved image
> back over the broken VM filesystem and you effectively have the same
> result as a snapshot...
>
> Do it again and again, until you get bored...
>
> Script it all up, for more convenience...
>
> Cheers,
>
> Bob Edwards.
> ttps://lists.samba.org/mailman/listinfo/linux [4]
>
>
>
> Links:
> ------
> [1] http://www.computerhope.com/jargon/c/conversi.htm
> [2] http://www.computerhope.com/jargon/o/operand.htm
> [3] http://www.computerhope.com/jargon/i/isoimage.htm
> [4] https://lists.samba.org/mailman/listinfo/linux
>

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