Re: Setting up storage Array for ASM
Date: Tue, 26 Apr 2011 09:19:19 -0500
Message-ID: <4DB6D467.9090109_at_ardentperf.com>
Ahhh! A religious, er, um, "storage best practice" question.
On 4/25/2011 6:42 PM, Steven Andrew wrote:
> if database is NOT going grow beyond allocated space, it shouldn't be
> a problem right.
Is that like saying that 640K memory should be enough for anything? :)
A few thoughts in response to the thread so far:
- the number 4 seems a little arbitrary to me, as indeed all "specific"
numbers that have been thrown out in this discussion
- 11gR2 does not actually require dedicated disks for OCR/vote although
it seems to me that most people are doing this. the OCR & vote can be
spread across disks that are also used for data.
- if you use ASM for redundancy then you get "hot spare capacity"
instead of hot spare disks, and achieve better spindle utilization and
higher IOPS -- but you lose a lot of potential capacity b/c you can't
use a parity scheme; only mirroring
- IMHO, avoiding parity-based RAID for mirroring and trying to segregate
traffic (e.g. redo) MIGHT get you AT BEST an extra 10-15% performance
over properly-configured alternatives. I made up that number, but the
point is - it's small. And that's only if you do it exactly right...
which is very difficult... I honestly doubt that it's making any
difference in most databases (ever since it became a popular religion).
And you lose a lot of possible capacity. Maybe parity is best for you.
- What if your DB is still small in 2 years and you decide that want to
use some of that disk for something different? Trying to shrink a LUN
which has been given to ASM is basically impossible right now.
- The question of what's most important for you (capacity, performance,
flexibility) is purely a business decision. There is no best practice
that can answer this for you.
Not that I have any of your answers, but if you're interested you can check out a presentation I gave at UKOUG and Collaborate this year about ASM lessons learned at a number of large companies. That was more about wide-scale adoptions, and your question sounds a bit different. Nonetheless: see "Premier League Peek" -> http://www.ardentperf.com/downloads
-Jeremy
-- http://www.ardentperf.com +1 312-725-9249 Jeremy Schneider Chicago -- http://www.freelists.org/webpage/oracle-lReceived on Tue Apr 26 2011 - 09:19:19 CDT