Re: ASM for single-instance 11g db server?

From: onedbguru <>
Date: Tue, 5 Apr 2011 18:02:50 -0700 (PDT)
Message-ID: <>

On Apr 5, 7:47 pm, Mladen Gogala <mgog..._at_no.address.invalid> wrote:
> On Tue, 05 Apr 2011 16:03:28 -0700, John Hurley wrote:
> > Moving some of your databases to RAID 5 makes a lot of sense for many
> > environments.  My test and dev databases are setup like that.  OLTP
> > production ... no thanks.
> Now this is something I can relate to. Yes, that's my attitude, too.
> --


If you end up with the EVA, I believe you will really like the performance you get. I have read the BAARF information and 10-15 years ago I might have agreed with that. But when you have 4-20+GB of cache on the front end, the ACK from a write to that cache is significantly faster than writing to the traditional RAID controllers of yesteryear - even RAID10. The SAN array technology has really changed the way we as DBA's should be looking at the mother-of-all-bottlenecks in any system. Having been an SysAdmin, SAN Admin and DBA, I spent a lot of hours tweaking systems for maximum performance - and when you deal with millions/transactions a day, you tend to figure out what works and what doesn't work. In many scenarios, I don't remember any measurable performance difference when just dealing with the RAID level on the array. What made the most difference was drive speed and then, that was for reads only. Due to the cache at the SAN array interface, write performance in all cases fluctuated only a few microseconds. The one time where there was a significant difference, it was attributed to another high-volume system competing for the bandwidth to the array. The answer was to move one of the systems to another array where they did not compete.

Moral of the story is that we as DBA's need to fully understand the entire "system" when dealing with performance. On many occasions I have encouraged those wanting to be a DBA to also learn the Sys,SAN,Net admin jobs at least sufficiently enough to know when they didn't configure stuff correctly. Especially in a RAC environment. [quote from me on more than a few environments "NO, do it the way I told you to do it and not the way you think it ought to be done - especially if you want it to actually work"]

John, the book you referenced is a great asset to any DBA's library. I once used it as teaching material for a group of DBAs and Sys Admins in a previous company. Received on Tue Apr 05 2011 - 20:02:50 CDT

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