Oracle-L: RE: EMC's DBTuner

From: Aponte, Tony <AponteT_at_hsn.net>
Date: Wed, 13 Mar 2002 20:03:25 -0800
Message-ID: <F001.00428A56.20020313200325@fatcity.com>

We've been using Precise/SQL since its early days. We also are using DBTuner for our servers that have Symmetrix devices attached. As far as we know it attaches to the SGA for read-only but you can probably verify that with pmap. But we've never had any problems with it interfering with the databases in any way.

I hope you are lucky enough to get it. Sampling from the SGA lets us throttle the interval to very high numbers that we couldn't achieve with any of our other tools. We start off at 5 samples per second and go higher when running traces. Imagine banging away at the v$/x$ tables 40 times per second and not bringing something to its knees. And speaking of traces, we use the features to selectively trace a session/program/user/osuser/module,etc. without having to use logon triggers or continuos loops selecting from v$session/v$process. Then there's that "what changed " tracking features. We've identified dropped indexes, dropped statistics, recreated tables and other changes that "nobody" remembers making but "nobody" was in the office on /mm/dd/yy and happened to drop and index for xyz table. You get the picture. The tool gave us an immediate return the first time we used it. We caught a problem that we weren't able to identify via the mere mortal sampling methods. By cranking the sampling interval to 5/second we observed that FirstWatch had been configured to do a check on the database by connecting as internal several times per second and viola, our problem with a high number of connections per hour was solved.

Ditto for the Symmetrix option. We had a recurring problem with a 7.3.4 hot backup. The backup progressed fine until it got to a certain area of one data file at which time the database hung. Yet we could not see anywhere where this data file coexisted with any other data file for any of our databases. This one stumped many fire-breathers that looked into it. The very first time we looked at the Symmetrix devices we noticed that 2 slices where very active and one of our rollback segment data files was stripped on them. We created another rbs tablespace on other devices and the problem was solved. A 5 minute return and most of it was spent appreciating each other's disbelief.

And if that's not enough their tech support folks are superior to any that we get from all of our other vendors. Puts OSS to shame.

And to any skeptical list members, no I do not receive any financial benefit from Precise's or EMC's sales whatsoever.

HTH and really hope you get to enjoy (yes, enjoy) providing a superior DBA service to your company with less tedious efforts.

Tony Aponte

-----Original Message-----
Sent: Wednesday, March 13, 2002 5:31 PM
To: Multiple recipients of list ORACLE-L

Now I know from previous posts that a number of folks are using EMC symmetric arrays, so I should get a couple of replies. Are any of you using their/Precise's DBTuner product as well? We had a demo today, but I'm still very leery of third party products that attach to Oracle's SGA. My point being that Oracle goes to quite a bit of effort through the latch mechanism to keep their processes out of each other's way. If your third party program, although only trying to read data, gets in the way all hell can & will break loose. Also if you can read something, you sure as heck can write there as well, even if not by intent.

Any experiences welcome.

Dick Goulet
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Author: Aponte, Tony
INET: AponteT_at_hsn.net

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