ADSM-L

Re: TDP vs. FlashCopy thoughts

2004-09-14 12:58:36
Subject: Re: TDP vs. FlashCopy thoughts
From: James Choate <jchoate AT SOURCE1INC DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 14 Sep 2004 10:59:02 -0600
To add to what Wanda is saying:
 
When a FlashCopy is initiated, the DB/Mail server that you are flashing should 
be quiesced prior to the FlashCopy being initiated.
 
FlashCopy can also be expensive. 

         
        -----Original Message----- 
        From: Prather, Wanda [mailto:Wanda.Prather AT JHUAPL DOT EDU] 
        Sent: Tue 9/14/2004 10:55 AM 
        To: ADSM-L AT VM.MARIST DOT EDU 
        Cc: 
        Subject: Re: TDP vs. FlashCopy thoughts
        
        

        I am not an expert in this area, but I think there are several issues
        involved.
        
        FlashCopy is taking a physical image of the VOLUME(s) involved.
        The Data Base manager doesn't know you're doing it.
        
        SO while it's easy and low cost to do the FlashCopy (it's pretty much an
        outboard hardware process), it doesn't copy or clear the logs that the 
DB
        management system uses.
        
        So the real question, as usual, WHAT are your recovery requirements?
        What are you going to do with that FlashCopy if somebody wants to 
restore
        the data base?
        
        If what they want is the ability to back out a bad transaction, you can 
do
        that with Oracle (for example), by restoring from the last full and then
        rolling forward from the journal, but you won't necessarily have a copy 
of
        the journal if all you have is a FlashCOpy.
        
        And Exchange and SQL server (I think) work like the TSM DB, when you 
take
        the DB backup, they clear their transaction logs.  So you would have to 
have
        some way to sync up your logs, if you used FlashCopy instead.
        
        SO you gotta work those issues out.  FlashCopy certainly is a great 
option
        for a DB manager that doesn't HAVE a TDP available, because you can  
stop
        your DB for just a few SECONDS and take a FlashCopy, instead of having 
the
        DB down for an hour to dump the volume as a flat file.
        
        Talk to your DBA about the recovery requirements for your particular 
DB's.
        
        WandaWanda Prather
        "I/O, I/O, It's all about I/O"  -(me)
        
        
        
        
        
        -----Original Message-----
        From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On 
Behalf Of
        Mike
        Sent: Tuesday, September 14, 2004 11:42 AM
        To: ADSM-L AT VM.MARIST DOT EDU
        Subject: TDP vs. FlashCopy thoughts
        
        
        Given that TSM has TDP for many databases and that TDP can do
        incremental backups at the record level. What are the thoughts
        for using TDB vs. using FlashCopy on an ESS/Shark? The FlashCopy
        must backup the entire database each time, unless the backup
        database could be mounted to a secondary server that could then
        start TDP on the backup copy...?
        
        Mike
        

<Prev in Thread] Current Thread [Next in Thread>