--- "Koivu, Lisa" <Lisa.Koivu@xxxxxxxxxxxxxxx> wrote: > Hello everyone, > > Windows 2003, v9204, 2 Clariion SANs 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. > 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. > > My fellow DBA supported my argument. The engineer > and the dw architect > wanted 3 disks. > > I am going to have i/o problems no matter what. > Concatenating 10 > physical disks into 1 logical disk is going to have > as much i/o latency > percentagewise as 6 physical disks concatenated into > 1 logical disk. > > Each disk has 1 bus, so to speak. These buses are > concatenated together > into 1 "device". (I'm being told that "device" is a > unix term and it > doesn't apply in Windows). 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". > 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. If your max IO size is 256 KB, then having more mount points should increase throughput. Datawarehouse - you'll likely want 1 MB reads (db_block_size * db_file_multiblock_read_count = 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. 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. 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. > Thank you > > Lisa Koivu > Senior Monkey > > Cendant Timeshare Resort Group > Orlando, FL, USA Pd __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free web site building tool. Try it! http://webhosting.yahoo.com/ps/sb/ ------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -------------------------------------------------------------