Backups with 9-STABLE -- Options?

[Adam Strohl]

On 6/10/2012 22:26, Karl Denninger wrote:
> Well, backup with snapshots don't do well EITHER on a database unless
> you can snapshot BOTH the dbms data store(s) and the transaction log
> store(s) /*at the exact same instant*/.  If you cannot then you're
> asking for trouble and are likely to get it.  But I've dealt with that
> particular "gotcha" problem in a different way for the DBMS I use
> (Postgresql)

You asked what would happen, not what was the best way to back up a SQL 
DB, but your point is valid.

Snapshots don't fix this issue entirely but drastically reduce the 
chance of a 100% broken backup.

SQL servers should be dumped out to disk (ie; mysql_dump) to avoid this 
or have a dedicated backup client (which means you're probably not using 
dump anyway).

> So basically what you're saying is that SU+J leaves you exposed to
> having no real backup option that provides a rational guarantee of the
> ability to restore the backup taken.

That's a bit of a gloss over on what I said.  My point was that you 
might end up missing something if its changing at the time the backup 
was taken.  It really depends on what specifically that server is doing.

There is also a consistency issue too, using snapshots makes it so that 
all the files make sense together, instead of the files getting more and 
more recent as the end of the backup block approaches.

-- 
Adam Strohl
http://www.ateamsystems.com/