Oracle ASM and FRA

Installed Oracle 11g R2. Configured ASM +DATA (for data files) and FRA (for backups).

If the FRA diskgroup (which is non-raided) stops working due to the disk failure, assume all other disks (OS and DATA) are still operating normally, will the Oracle database can still be used/accessed by the user?
eugenecaAsked:
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slightwv (䄆 Netminder)Connect With a Mentor Commented:
Yes. The FRA is used for backup and recovery.

The only issue you may have and I've not set this up is if you are using flashback logs and Oracle needs to write one, it might cause an issue if that disk is unavailable.

http://docs.oracle.com/cd/E11882_01/server.112/e10897/backrest.htm#ADMQS0921

Planning Space Usage and Location for the Fast Recovery Area

You should place the fast recovery area on a separate disk from the working set of database files. Otherwise, the disk becomes a single point of failure for your database.
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eugenecaAuthor Commented:
Ideally, the FRA should be on RAID 1.  But due to the configuration limitation, I can only use one disk for FRA and the spare one for holding the multiplexing files such as REDO, CONTROL, and ARCHIVE.

By this way, DATA (Two ASM disks + raid 1),  FRA (One ASM disk, non-raid), and Multiplexing (one regular disk, non-raid).

DATA (redo log + control + others) --> multiplexes to --> Multiplex Disk (mentioned above)
FRA (archive + all other backups) --> multiplexes to --> Multiplex Disk (mentioned above)


Like to hear your opinion and comments.



P.S. The FRA will hold the backups only, nothing else.  And DATA (Two ASM disks + raid 1) will hold the regular oracle data files + redo, control and other related files, nothing else.
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Chakravarthi AyyalaConnect With a Mentor Database AdministratorCommented:
If the FRA diskgroup (which is non-raided) stops working due to the disk failure, assume all other disks (OS and DATA) are still operating normally, will the Oracle database can still be used/accessed by the user?
  => eugeneca:  if i understand your question correctly, you are asking if the disk group where you defined your FRA is full, will the DB stop functioning?
        => The answer is no as, "when the fast recovery area is full, Oracle Database automatically deletes eligible files to reclaim space in the recovery area as needed."

Ref: http://www.orastudy.com/oradoc/selfstu/fusion/backup.1111/e10642/rcmconfb.htm#i1019160
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slightwv (䄆 Netminder) Commented:
You realize that losing the FRA can invalidate your backups?

Also if you use the single disk for multiplexed redo and control, you can have issues moving forward.

Since you have 3 disks, can you not take the write penalty and go RAID5 for everything?

My guess is with only 3 disks, overall throughput is not a high priority of this system.
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eugenecaAuthor Commented:
Configuration Plan:

Disk 1 (raid 1) for OS and Oracle DBMS software
Disk 2 (raid 1) + Disk 3 (raid 1) for +DATA (asm based)
Disk 4 (non-raid) for FRA  (asm based)
Disk 5 (non-raid) for multiplexing

Another configuration is getting rid of the multiplexing:

Disk 1 (raid 1) for OS and Oracle DBMS software
Disk 2 (raid 1) + Disk 3 (raid 1) for +DATA (asm based)
Disk 4 (raid 1) for FRA  (asm based)
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eugenecaAuthor Commented:
To answer ReliableDBA's question: "you are asking if the disk group where you defined your FRA is full, will the DB stop functioning?"


Actually, no.  If the FRA disk which contains the backups only, fails, will the Oracle system can still funtion so that users can access it as usual?
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slightwv (䄆 Netminder) Commented:
What is your performance requirements?
How large is your system?


Why not: disk 1-4 raid5,  disk 5 hot spare?

There are many debates out there on what to put on what RAID but for smaller systems, take the write hit and go RAID5.  The read increase will normally balance it out.
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