Just to add my two cents we were using Shadow copies for HARDWARE
failure only, but the shadow copy was being done on another array and
one day that array failed. When the Shadow was unavailable, I had to
drop the shadow from my databases because all transactions STOPPED. Now
I rely on replication and regular backups. The Shadow caused me grief.



_____

From: Alan McDonald [mailto:alan@...]
Sent: Tuesday, June 29, 2004 10:49 AM
To: firebird-support@yahoogroups.com
Subject: RE: [firebird-support] Server 2003 and connection speed

> No, I think you don't understand the point of volume shadow copies.
> Volume shadow copies (from a semantic point of view) clone all files
> atmoically. The database server can continue working on its version,

the

> shadow copy has it's own. For the very short period of time, the
> os requires
> for instantiating the volume shadow, all accesses are stalled.
>
> > Again - they may be like db transactions semantically but they
> are not the
> same. The OS and NTBACKUP do not know about the way FB structures
> it's paged
> data.
>
> It simply does not need to. As power failures don't need to.
>
> Regards,
> Steffen

Please also bear in mind that with the use of database shadows, if
that's
what you are really referring to, you should not rely on the shadow copy
as
a database backup. Under this scheme, corruptions in the master are
instantaneously included in the shadow version. They are good for
protection
against hardware failure and for that reason you need the shadow created
on
another physical disk (not the same disk). But there is no substitute
for a
good regular gbak/test restore regime as far as secure backups are
concerned.
Alan




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