RE: Oracle Parallel Server / Other HA Solutions

From: Mohan, Ross <Ross.Mohan_at_PictureVision.com>
Date: Thu, 12 Oct 2000 13:29:25 -0400
Message-Id: <10647.119094@fatcity.com>

Dick,

What if ( for the sake of argument ) the odds of disk failing were one in NINETY BAZILLION? Would you still not like OPS?

And what if ( again for the sake of argument ) Mary needed only "two nines" of uptime? Wouldn't a simple non-HA standby database be fine?

My point:

ANY "in the weeds" discussion of this stuff ( redundancy, platform, uptime, etc) must include:

Biz requirements (total downtime, failover constraints,etc.)
available budgets
timeline ( time to online...training...development)
MTBF, hw costs, sw and support costs.

We no longer have the luxury of advocating Standby versus OPS versus HA versus Shareplex
versus....whatever.

at a low level of analysis, they ALL work.

at a high level of analysis.....ALOT of study, research, and testing is needed.

YMMV, IMHO, etc.....

hth

Ross Mohan

-----Original Message-----
From: dgoulet_at_vicr.com [mailto:dgoulet_at_vicr.com] Sent: Thursday, October 12, 2000 12:48 PM To: Multiple recipients of list ORACLE-L Subject: Re:Oracle Parallel Server / Other HA Solutions

Mary,

OH, this is a good one. Basically we've looked this stuff over six times to
Sunday. While OPS will provide some degree of redundancy all it can cover is an
instance failure for other than a disk drive failure (things like cpu or power
supply or memory). Since in an OPS environment both instances share the same
disk drives a failure in the disk farm is critical, period, to BOTH instances.
OK, Where are we going here:

High availability HP9000 systems with multiple CPU's, power supplies, and other suggested items from HP. This way the computer does what is called a soft fail. Parts fail & others take over the workload. The computer and consequently the instance, does not fail although response time may take a hit. Also the parts are hot swappable so one does not have to shutdown for repairs.
EMC Symetrix disk array with full three way mirrors & hot swap drives. This way we can offload the backup tasks to a dedicated part of the Symetrix system and not utilize computer resources. The third mirror or "Business Continuation Volume" as they call it can be used to create a hot standby or backup database or even a reporting DB if desired. One other item in this is that if a drive in the main mirrors fails, it's BCV cousin can be re-silvered much faster than when the bad drive is replaced.
HP ServiceGuard and EMC's equivalent (not sure what the name is). These software products simply scan around looking for trouble, A cpu that misses a beat, a memory chip with a check sum error or a power supply that's drifting, or a disk that's having errors. When the product finds a problem, it "phones home" thereby letting you replace the faulty component before it hard fails.

Where I see OPS coming into the equation is to increase capacity to your WEB site. Mainly if your over taxing the computer you have you can just add another
into the cluster for added processing power. Doesn't do much for redundancy in
this case. In my view of the world, the weakest link in the mess is those mechanical drives that we still depend on. So mirror them to kingdom come.

Now, If I understand the EMC folks correctly, they do have a product that lets
you keep that mirror in another facility all together via a dedicated T1. Now
that would allow for OPS to do the job since the drives would be in separate facilities. But I wonder, if trash lands on the prime drive in facility one,
does that replicate to facility 2?? I'd think so. And would you need basically
a 4 way mirror for drive protection?? Could get VERY expensive very fast.

Dick Goulet

____________________Reply Separator____________________
Author: "Ruiz; Mary A (CAP; CDI)" <Mary.Ruiz_at_gecapital.com>
Date:       10/12/00 6:58 AM

I need a little advice. We have a fairly new (< 1 year) 8.1.5 instance to support my company's internet business. We recently changed our network solutions provider and now my management wants to achieve a higher level of redundancy than it currently does with mirrored disks. The solution being proposed by my Sysadmin is an Oracle Parallel Server solution. Some background is in order here - we have always shut our databases down at night for backups. I am not highly skilled in backup and recovery although I tried some of the hot backup techniques from this list and was able to recover successfully to another server. I noticed that the course offered by Oracle in OPS has backup and recovery as well as performance tuning as pre-requisites, which indicates to me that OPS could be extremely challenging. Also, I have read mainly unfavorable comments about OPS from this list, but most of those comments were based on the Oracle 7 implementations (High administrative costs, difficult to implement, etc.).

Have things improved with Oracle 8i ? Is OPS worth pursuing? Or should I convince my management that extra $$ spent in, say, a hot standby database is well worth it? Is there any other solution that would not involve a second set of disks, rather a second database on the same set of disks ??

Thanks in advance,
Mary Ruiz / Atlanta

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Author: Ruiz, Mary A (CAP, CDI)
INET: Mary.Ruiz_at_gecapital.com

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