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Home -> Community -> Mailing Lists -> Oracle-L -> RE: [new info] Redhat Advanced Server Dev Edition - RAC
If you asked me last week I might not have formulated much of an opinion,
but I have been tainted by Mogens presentation on RAC or Not To RAC.
Here are some questions you need to ask...
Why not go with a box capable of the CPU's you will eventually need. Why add machines when adding CPU's might be just fine. Will these apps really not run on 64 CPU's?
The added complexity of RAC and administration needs to be a factor in calculating your target uptime? My experience has been that most database downtime is a result of the following items.
RAC doesn't fix any of these things. However, a stand-by running a few hours behind could provide feasible solutions to most of these items.
Just recently I saw a HACMP cluster (not RAC) come down causing a 1 hour outage as a result of the instructions provided directly from an IBM support rep to the Unix admin. The complexity of HA was the issue, so point #1 only becomes more likely as you add the complexity of running RAC to your environment.
If you could chart all this stuff I got to feel that at some point the likelihood of one of issues above surpasses the likelihood of an actual hardware failure causing an outage.
I think another point made during the presentation is that some very unique and hard to pinpoint errors can arise from running RAC. Don't be surprised if the answer back from Oracle is very vague (i.e. perhaps parameter X is set to high when circumstance Y happens...
My 2 cents...
-----Original Message-----
Sent: Thursday, February 13, 2003 9:40 AM
To: Multiple recipients of list ORACLE-L
With all this discussion on "Why RAC?", I thought I'd chime in with our reasoning, at least as it stands before any testing.
We currently have a few "major" databases for our ERP/MRP system, Engineering drawings, and "legacy" (I loathe that word) data. These databases are spread across three larger systems: Solaris, HP/UX, and OpenVMS. They are set up as any three independant systems with their own disks, own CPUs, own memory, etc. These relatively expensive systems are under utilized, and finally, are beginning to show their age (up to six years old).
By combining these systems under a single system, we will be saving money in hardware cost (future upgrades and repair) as well as in service contracts, not to mention the utimate savings -- computer room floorspace! What I don't want to do is have the consolidation negatively affect the DBs in performance or downtime (perceived or real). So, the idea right now is to use "commodity" (read: "inexpensive") servers, dual Intel (AMD???) 1Us, with a SAN, and 9iRAC.
The theory being that while we'll take an initial kick in the fiscal crotch with the Oracle licensing, since we currently refuse to let go of our Concurrent User, we'll come out ahead in the long run with the added performance and unlimited user (per CPU) licensing. Also, with the commodity servers, we can switch out the server for faster CPUs without incurring more licensing cost should the need arise (yes, Cary, I'm well aware of the "CPU Upgrade Myth"!).
With our testing, I hope to see that we'll be able to provide better uptime and performance with RAC than the total sum of the current boxes (save for the uptime on the OpenVMS box, which has 10 minutes of total downtime in the past 770+ days).
Any comments on this? In the interest of bandwidth and brevity, I've been way too brief here. This should really be discussed over Guinness.
Thx!
Rich
Rich Jesse System/Database Administrator rich.jesse_at_qtiworld.com Quad/Tech International, Sussex, WI USA
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