Re: Backup and Recovery and DR - RMAN vs. NOT
- From: "Mark Brinsmead" <pythianbrinsmead@xxxxxxxxx>
- To: paulastankus@xxxxxxxxx
- Date: Thu, 4 May 2006 02:52:50 -0400
You know, it is ironic. I have been promising myself that I would not wade
back into this thread tonight, but the irony (and maybe boredom) of my
situation draws me in like a moth to a flame...
As last as it was when I stopped writing (or rambling) last night, it is a
great deal later now. And yet, here I sit, posting a followup at 2:30 AM.
But that's not ironic. What *is* ironic is that it is not insomnia that
leads me to do this, but rather the fact that I am sitting around waiting
for a rather critical database recovery to complete.
Even more ironic are the circumstances of this recovery.
Yesterday (was it only yesterday? Well, maybe not, since this is no longer
really "today" either...) my employer took on a new client. This new
client is a small-to-medium (I think) sized business who recently lost their
only DBA on very short notice. Sadly for them (and me!) they promptly lost
a database server on even shorter notice.
The details of the loss are immaterial -- it was simply one of those unhappy
situation where a database server goes down -- hard -- and never really
comes all the way back up again. In this case, a crash caused some
corruption (an event I haven't seen in years -- I had almost thought it was
impossible!), and long story made short (for everybody but me!) we now need
a full database recovery.
Did I mention that my employer only took on the client yesterday? We hadn't
had time yet to do more than exchange phone numbers before we were pitched
into a full-blown server recovery.
Now, here's the "happy" part of the story. The previous DBA actually made
backups. It took a little while (and some very gracious assistance) to
determine how and where the backups were made, but once it was determined
that they were done with RMAN, my worries were over.
Although I had never seen this server or database before, and in fact the
platform is not even one that I am 100% comfortable with, as soon as I knew
the backups had been done with RMAN, I *instantly* knew how to recover
them! Pretty much all I had do do was this:
1. Make lots of phone calls, and try lots to stuff to eliminate all
possibility that we could proceed without recovering from backups.
2. Make a few more phone calls. Just because.
3. Make a cold backup of the broken database (because you never know...)
4. Type (more or less):
rman << EOF
connect target / ;
connect catalog mycat/*****@cat.db -- Determining the right credentials
was the *hardest* part!
restore database ;
recover database ;
open database ;
EOF
And that's what I was rambling about last night: the fact that this process
is not "about" backups; it's about *recovery*!
I've always thought that split-mirror (or SnapCopy, or BCV, or FlashCopy,
or...) backups were really cool. But I am exceedingly happy right now (if
that word can be used to describe anyone in my present circumstances) that
my predecessor at this particular site did not do "cool" backups. Instead,
he chose to do "recoverable" backups. And I am extremely grateful for
that. Or, at least, I will be once this database is actually recovered...
;-)
Paula, do you feel you need anything more to convice your manager of the
merits of RMAN? I can certainly provide *lots* of bullet points on the
subject (which had been my original plan) but I think this little story
ought to be a compelling an argument as you'll ever need.
--
Cheers,
-- Mark Brinsmead
Staff DBA,
The Pythian Group
http://www.pythian.com/blogs
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