Data file on diffent disk
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Thread: Data file on diffent disk

  1. #1
    Join Date
    Aug 2001
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    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

  2. #2
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    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

  3. #3
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    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.

  4. #4
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    use RAID 0

  5. #5
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    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

  6. #6
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    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.

    Don't be afraid to try something new. Amateurs built the Ark, professionals built the Titanic

  7. #7
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    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

  8. #8
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    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.
    Jurij Modic
    ASCII a stupid question, get a stupid ANSI
    24 hours in a day .... 24 beer in a case .... coincidence?

  9. #9
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    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

  10. #10
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    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.
    Don't be afraid to try something new. Amateurs built the Ark, professionals built the Titanic

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