Re: block chg tracking
Date: Sun, 15 Feb 2015 15:57:16 -0500
Message-ID: <54E1082C.5020707_at_yahoo.com>
Because the goal of the backup is to provide the ability to get the database back as soon as possible. I doubt that your CIO will be very pleased if you save some IO operations but extend the recovery time for a few hours, in the world where the cost of downtime is measured in hundreds of thousands of dollars. If you are a major bank, then the cost of downtime is enormous. The same goes for the sites like Amazon. If www.amazon.com goes down, the customers will go to walmart.com or alike. The costs of downtime can be enormous. The goal of any backup strategy is to minimize downtime, not to save IO operations. That is why backups are usually scheduled for wee hours of the night.
On 02/15/2015 03:14 PM, Ram Raman wrote:
>
> Mladen, why would you say the 'goal is not reducing the reads' in this
> context? I would prefer lesser reads (lesser CPU and IO) while doing
> backups. BCT is very handy not just for prod, but for several non prod
> DBs too where we do not pay for the standby solutions like DG, etc. I
> will take BCT over commvault for the DBs we maintain, most of them
> under a TB.
> What is the size of the DB for which commvault's compression beats BCT
> significantly in recovery time.
>
>
> On Sun, Feb 15, 2015 at 11:24 AM, Mladen Gogala
> <dmarc-noreply_at_freelists.org <mailto:dmarc-noreply_at_freelists.org>> wrote:
>
> On 02/15/2015 11:47 AM, Jared Still wrote:
>
> Hi Mladen,
>
> Though dedup reduces the size on the backend, it does nothing
> for database impact.
>
> As you know BCT reduces the reads on the db by RMAN, so I am a
> little confused by this statement.
>
>
> That is true, but the goal is not reducing the reads, the goal is
> to restore database in the shortest time possible. De-duplication
> also speeds things up, because everything is read, but not
> everything is written. You get far fewer disk writes and, if the
> storage medium is connected by network, far less network traffic.
> Given that a full backup must be restored, the difference is
> whether there will be a need for applying additional incremental
> backups.
>
>
-- Mladen Gogala Oracle DBA http://mgogala.freehostia.com -- http://www.freelists.org/webpage/oracle-lReceived on Sun Feb 15 2015 - 21:57:16 CET