Data file on diffent disk

[mike73]

assume I have 6 disks on my server. Oracle suggest that we should have control file and redo log files on different disks b/c of I/O and rollback on another seperate disk. From this advise, this is how I place my files. I would put three control files and redo logfiles on disk 1,2,3 and I will put rollback on disk 4 so I have only two disk which is disk 5 and 6 to place my datafiles, but if I put all of my datafiles and index on these two disk, there is an issue with Oracle too b/c the activity is not spread around so that these two disks will have to perform the extra work.


any advise for the above for how I should handle the datafile efficiently ???

Thanks

[pando]

Originally posted by mike73
assume I have 6 disks on my server. Oracle suggest that we should have control file and redo log files on different disks b/c of I/O

It's not because of I/O, it is to avoid the loss of any control files and redo logs, redologs should be at least 2 groups, one per disk so is control file. Redo logs are written sequentially so there is no problem putting them in same disk

[mike73]

Pando,

I am sorry if I am confused you. What I mean is if I have 6 disk in total and 3 of them I use for control files and redo log files and one of them for rollback so I have only 2 left for my data files and indexes. The question is if I have only 2 disks left and I put all the of my datafiles and index files, these two disks will be heavy used. Can I use only two disk for my datafiles ??? What is the solutions ??? How are you going to lay out if you were me having 6 disks on your box ???

Please give me some advises.

[pando]

use RAID 0

[mike73]

Pando,

Using raid 0 is not going to be my option, I like to get your opinion of how you lay out your files if you have six disks.

Thanks

[brhynold]

Just because you have control files and logfiles on the first 3 disks doesn't mean you can't put datafiles on those disks as well. I have never seen a system that uses disk specifically for control files, redo logs and rollback segments.

Oracle recommends you have control files on different disk so save you if you lose a disk. The same goes for redo logs. That way if you lose a disk you don't have a DB crash. It has nothing to do with I/O contention

Data datafiles and index datafile should be on different disks to save I/O contention because as tables are written to and read from indexes are as well which is where you get your contention.

Datafiles, redo logs and control files can co-exist on the same disk.

[mike73]

if you have redo log files the same disk with datafile which casue LGWR and DBWR will write to datafile and redo log file at the same time. That's I/O , isn't it

Please correct me if I am wrong

[jmodic]

Originally posted by pando
use RAID 0

On production system????!!!! Pando, I'm sure you ment RAID1 or RAID10 or (even) RAID5, surely not RAID0.

[mike73]

I am running raid 5, this is only development database but still I like to have get into the habit of doing thing right at the first time even it's not production

I think it will bring down your performance if datafiles and redo log files on the same disk b/c LGWR and DBWR and into these two files at the same time so that I don't know what is the best way to lay out the files on different disks ???

Anyone with advise are welcome !!!!1

[brhynold]

Ok guys correct me if I am wrong but do any of you have only logs and control files on disks because right now I am administering 17 production databases and we have our log files and control files on the same disks as our datafiles.

I have never seen anywhere in the Oracle manuals where your suppose to keep the control and logfiles seperate from the datafiles.