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962486 wrote:Performance will depend on of your Storage Design not only ASM Design.
We are planning to deploy Oracle RAC 11gR2 on our PROD databases envoirnment. We have 6 databases and the largest database is 140GB of size and rest of the databases are ranging from 15Gb to 90GB. Also we are getting 1TB space from SAN for RAC. Currently used space by Oracle mountpont /u01 is 585Gb and total space is 740GB for exssiting NON-RAC databases.
Need to know how do we design the ASM diskgroups with external redundancy. Goal is to get the best performance from ASM disks.
1) Do we create single diskgroup with 4 LUNs of 200GB size. Also tell us how much size of FRA and VOTING diskgroup should be created.Oracle Recommend:
<li> Configure two disk groups, one for data and the other for the fast recovery area.
<li> A minimum of four LUNs (Oracle ASM disks) of equal size and performance is recommended for each disk group.
About Voting and OCR stored on ASM. I recommend you read this:
2) Do we create seperate diskgroup for all the databases. i.e 6 databases 6 diskgroup and each diskgroup with one disk of depending upon the size of the database.The I/O operations (performance) is more linked with Storage. However if you have one Array on storage shared by all databases have no sense to create a diskgroup for each database. Because this data on ASM will be separated but on Storage not. Think about I/O concurrence on Storage and not only on ASM.
3) Do we create 3 diskgroups with 3 disks in each diskgroup of 100GB. So each diskgroup will be of 300GB.Do you have area on storage (I mean physical disks) to create one array for each diskgroup? If not forget this, this recommendation is for those wich have possiblity to create different array on storage (using set of phisycal disks dedicated) for each diskgroup.
4) Also need to know if we need to create seperate diskgroups for ARCHIVE,REDOLOGS, like if option 2 is choosen, then create one diskgroup for each databaseas DATA and ARCHIVE and REDOLOG diskgroups for each database as well OR
archive and redologs files will be part of DATA diskgroup.
I recommend you create one Diskgroup to all database and a Diskgroup to FRA.
Each diskgroup should have at least 4 ASM Disk (i.e Lun) with same capacity to maintain balance.
If you can, also I recommend you create one Array for each Diskgroup (FRA and DATA).
Edited by: Levi Pereira on Oct 1, 2012 4:05 PM
Levi has some good info, though in testing on Symmetrix and Clariion arrays with dm-multipath, I've actually seen better performance separating out the DGs by database but YMMV.
What I'd suggest doing is something along the lines of setting up your DGs like so:
on the OCR disk group, even if you have RAID at the device level on your LUNs you will want to have a minimum of 3 devices and redundancy of NORMAL for your OCR diskgroup as this will cause it to create 3 voting files. in 11gR2, the number of voting files is determined by the diskgroup redundancy in which you store them. 1 VOTING for EXTERNAL, 3 for NORMAL and 5 for HIGH redundancy.
It's best that you have more than one.