[Info-vax] OT(?): Linux: developed by corporates. *NOT* developed by unpaid volunteers.

[johnwallace4 at yahoo.co.uk]

On Sunday, 29 March 2015 17:44:51 UTC+1, David Froble  wrote:
> Kerry Main wrote:
> 
> > Ask all of those backup vendors who are doing well selling backup
> > products for Windows and Linux when those platforms includes "free"
> > platform utilities to do this.
> 
> Oh, I must be really dense.  Can you tell me how to backup and restore a 
> weendoze system disk?  Using the backup provided with weendoze ..
> 
> Without that, you don't really have a usable backup, do you?

You need to stay in more and play with Windows :) Or maybe I need to get
out more - I'm working on it :)

In the early daze of Windows NT, MS bundled a cut-down version of a 
commercial backup tool. I forget which one it was (this was when I
had NT at home but not at work, and I had the joys of a Travan tape,
before paying £150 or so for a DVD writer and/or inheriting a discarded
TLZ04). 

This software ran under Windows, which didn't fill me with joy, for all
the same reasons that have been written wrt /IGNORE=INTERLOCK.

So my preferred option in the early daze was actually Norton Ghost
(think Standalone Backup). It used a DOS-based tool for both backup and
restore. Full disk (or partition) image only, though file by file 
restore under Windows was a later development.

In recent (and indeed not so recent) years the idea of shutting down
to take a backup has fallen out of favour. Sadly, Ghost eventually fell
in with the "do it live" gang and I stopped using it.

Around the same time, "enterprise" backup packages were (re-)designed
to work with "backup agents" for major "enterprise" software packages,
which magically ensure that the backup package gets to see a consistent
set of data. Allegedly.

More recently still, MS have rediscovered 'StorageWorks Virtual Replicator
for Windows NT'. SVR was a bit like Host Based Volume Shadowing, except
copy-on-write as you go along, rather than copy a whole device, so you
could do useful things with it with a relatively small amount of 'free'
space. And MS have provided a way for applications to control it.

This seems to have resulted in there being a backup package in (some
flavours of?) Windows 7. And snapshotting is also used by non-MS packages
including the one I am using this week (Easeus, which seems much more
robust than the MS-supplied one). Package takes a snapshot (which doesn't
occupy any space unless writes occur before the backup completes) and the
backup data is copied from the point-in-time image of the disk(s).

But as with dismembering a shadow set on VMS and taking a backup from
that, the snapshot doesn't guarantee that the backup is self-consistent.
Only the applications (and OS components) know when it's *safe* to take
the snapshit.

And there's more. I've used the MS-supplied backup on a number of Win7
systems. Eventually, it breaks, and refuses to take a backup. Ever again.

There never seems to be a definitive answer as to why, and obviously
the acceptable answer nowadays is "don't diagnose, don't fix, just
reinstall the OS and hope it doesn't happen again". At least it's quick.

My best guess for the failures I've seen is that they result from the 
pre-reserved "copy-on-write" space becoming full, and either there's
no mechanism to extend it, or (more likely) sometimes it doesn't work.
Other suggestions very welcome (but not necessarily here).

Note: the above mostly talks about taking a backup. 

Restore is a different kettle of worms. I'll stick with the low end
packages I know, not the "enterprise" stuff (some of which are, at least
in the UK and Europe, supported by HP).

Selective file by file restore with some of these things is easy - an
explorer-like interface is typically available, but you may have to work
out where the file you are looking for is available. (some flavours of?)
Windows 7 have a built in "previous versions" feature which work with the
built-in Win7 backup. If it was trustworthy, it might simplify some of
this. See above - not trustworthy imo, so I don't use this feature.

"Bare metal" restore typically involves a bootable recovery disk with
an application that knows how to read the "save set" and restore it. Some
packages even claim to be able to restore a Windows setup onto different
hardware than the original system. 

Products I've tried post-Ghost (which was DOS based) have typically used
a Linux-based recovery setup, as Windows isn't the  right tool for that
job (one size does not fit all, remember - unless you're Microsoft or
Microsoft-dependent).

Any clearer?


TL;DR: yes MS have shipped a backup package with Windows at various
times including NT3, NT4, and Win7 (also maybe Win2K, maybe WinXP). Have
they been useful? Somewhat. Is the Win7 package useful? Probably not
very, in my experience.