| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> RE: [oracle-l] Re: The Holy War: Disks
Hi Paul, thanks so much for your response.=20
Part of my problem is that I don't know that much about Windows. Do you offhand know how I can find out what the max i/o size has been configured to? I'm looking and it's not jumping out at me (yet). I have asked this question before and never got an answer.=20
As far as the multipathing goes - I assume yes. I don't know for sure.
Degree of parallelism hasn't been decided yet. It's actually a 2cpu box running ~3GHz cpu's. I have never seen the cpu pinned. It's always been i/o, cpu is always sitting at 40% max. =20
I'll see if I can find the articles you are referring to.=20
Thanks again. Your response is very helpful, all I need is a shove in the right direction (and the cobwebs knocked out of my head)
Lisa
-----Original Message-----
From: Paul Drake [mailto:discgolfdba_at_yahoo.com]=20
Sent: Tuesday, January 27, 2004 5:21 PM
To: oracle-l_at_freelists.org
Subject: [oracle-l] Re: The Holy War: Disks
I have a site with a CX400 in use, with W2K3 Server, but its not yet in production, so there isn't much IO to look at. I might be able to run a few tests there.
Its a small oltp database and its clone.
> I have just been given ~1tb of disk on a new SAN.=20
> The engineer wanted
> to give me 3 huge (maxed out) disks, 2 350GB and a
> third with the
> remainder. I argued for 6 disks similarly sized. =20
>=20
>=20
>=20
A LUN is a LUN is a LUN.
It is apportioned within the management software the
same way.
> So, concatenating 10
> disks (and buses)
> together for 1 high speed disk is going to result in
> having even more
> data on the other side of the "straw". =20
>=20
Lisa, did you hike the max IO_size for the operating system? It was 256 KB on w2k by default, I did not check it on w2k3 server. Connor McDonald had a referereference to the setting some time ago. I think I have an article related to hiking this in the regsitry, a max size of 1 MB was possible.
Is the oracle server multipathed over multiple Fibrechannel host bus adapters, or at least over multiple ports? If not, its likely that even a 2 Gbps connection will be the rate limiting factor, if you have 30 drives mounted on 3 different buses. You probably wanted multipathing for availability purposes anyways.
> I strongly feel if I have 3 disks instead of 6, my
> options for
> alleviating i/o contention are very limited. =20
If your max IO size is 256 KB, then having more mount
points should increase throughput. Datawarehouse -
you'll likely want 1 MB reads=20
(db_block_size * db_file_multiblock_read_count =3D 1
MB).
> Any i/o balancing would be
> messier and more difficult. We are going with 6
> disks instead of 3 with
> the understanding that when we add more disk to this
> server, we'll
> evaluate performance of the 6 disks and reconsider.=20
what is the degree of parallelization that will be used? I'm assumming that you'll only have a 4-way box, that may appear as an 8-way box with SMT enabled.
> As far as I know, the Clariion SANs don't have the
> whizbang
> functionality of the Symmetrix that allows moving
> datafiles at the
> physical level within the SAN to alleviate i/o
> hotspots. I also don't
> buy the argument that the SAN cache should alleviate
> i/o problems. =20
As far as large table scans (and other multiblock IO), its more a matter of IF read-ahead is effective.
> This
> is a data warehouse that has the potential to become
> enormous and it
> will blow the size of any SAN cache during data
> loads, guaranteed.
good article in SysAdmin magazine several months ago, comparing cache-centric vs. throughput-centric external storage units. This unit should be good in the non-cache-centric arena.
> Is anyone in this type of environment? What have
> your experiences been?
> Any and all comments are welcome. =20
> Thank you
>=20
>=20
Pd
"The sender believes that this E-Mail and any attachments were free of = any virus, worm, Trojan horse, and/or malicious code when sent. This = message and its attachments could have been infected during = transmission. By reading the message and opening any attachments, the = recipient accepts full responsibility for taking proactive and remedial = action about viruses and other defects. The sender's business entity is = not liable for any loss or damage arising in any way from this message = or its attachments."
-- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------Received on Wed Jan 28 2004 - 08:52:27 CST
 |
 |