Re: database network performance requirements

From: Tim X <>
Date: Sun, 07 Feb 2010 12:43:00 +1100
Message-ID: <>

hpuxrac <> writes:

> On Feb 6, 12:31 pm, Ryan_Hoffman <> wrote:
> snip
>> Can you comment on SYNC backup (realtime)?  Is there a particular
>> latency and loss threshold you wouldn't want to exceed; since these
>> directly impact the application response for the client?
>> I've found a variety of marketing names the db vendors use for SYNC
>> and ASYNC backups.  I'm curious if there are generic names DBA's use
>> for these functions?  I was thinking 'hot standby' for SYNC and
>> perhaps 'WAN replication' for ASYNC.
> You lost me completely here.
> You backup an Oracle database using rman. Best backups are done to
> disk since they go much faster than backups to tape and if you have to
> use the backup recovery from disk versus tape is much faster.

Rman is ONE way of backing up an Oracle database, but its not the only way and it may not necessarily be the best way, depending on Oracle version. It would generally be the preferred way on nearly all current Oracle versions.

I think what the OP was asking about was database agnostic/neutral terminology rather than Oracle specific. If you need to work with a bunch of network engineers, more than likely talking about RMAN is going to be meaningless to them.

With respect to the OPs other questions, I'm not sure I can give an answer. This is partly due to much of what your asking being dependent on site specific variables. What latency is acceptable where you are may not be acceptable where I am. The size of the databases, the type of applicaiton and how fast your data changes, the costs of your local and remote storage, types of storage available and its support for tiered storage, snapshots etc all have a bearing on what you can do, what you should do and what you can afford to do. there is no standard formula that can be provided. Its a difficult question and one where I know enough to know I don't know enough!

Based on experiences where I am at present, we have been seeing around 60% increase in data storage requirements per year (not just Oracle DBs). We have had to implement tiered storage solution and differentiate between the backup frequencies based on the storage tier i.e. more frequent backups for the very dynamic data and less frequent backups for the data on the slower more static storage tiers (actually, its not that simple - the formula to determine backup frequency has to take factors like risk impact, business impact, data value etc into account as well). The backup system we implemented in 2004 only lasted half the projected lifetime because it wasn't fast enough to handle the amount of data being kbacked up. We could have extended this slightly by using more incremental backups and compressed backups, but of course the downside with doing tis is longer restores, which you need to consider from a DR and business continuity perspective. Our failure was in adequately predicting data growth. We estimated about a 30% growth per year, which turned out to be about half what it really was. In our defense, much of the growth was due to changes in business processes and new services that we were not aware of at the time of estimate. The real failure was in the projects that implemented the new services and changes not incorporating backup into their planning.

To deal with things like latencies, temporary network outages etc and to handle both backup and restore requirements, we rman backup to fairly fast SAN storage, do snapshots of that backup onto slower local storage. Move the snapshots to our remote backup system (10Bgit network connection) onto local storage attached to a tape bac,backup system with a tape jukebox with 8 high speed tape backups. Each week, tapes are moved to a third off site location with a fireproof safe. The tape jukebox can be increased in size and I expect, given current data growth, will need to be before the system is totally replaced with whatever is the better technology at the time.

More than likely, your best solution will not be found just working with DBAs or just with network engineers. You need to find a solution working with all thre areas, the dBAs, the network engineeers and someone whose area of expertise is the low level management and administration of backups. It is a rare individual who can be up to speed on all three areas if the requirements are at all demanding/complex. the two things I'd keep in mind is that backup is only half the story - a backup solution is only as good as the restoration process it supports. No point backing up f you cnnot restore. The second most important point and the one which is ignored/overlooked more often than any other is that you cannot be certain about your backups unless you do regular bare metal restores. This is rarely done because of the time it takes and the fact you need the necessary duplicated envrionments to do this without impacting on core business, but it has to be the one most common point of failure with backup systems.


tcross (at) rapttech dot com dot au
Received on Sat Feb 06 2010 - 19:43:00 CST

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