RAID 1+0 or RAID 5

[Jack Fan]

All,

My server spec is DL380 + Smart Array 5i + 72GB/15krpm * 6.

RAID 1+0 or RAID 5 for disk array on server, which raid mode is better for oracle database run?

We should based on IOPS to consider it, right?

Jack Fan

[Marek Nelec]

Once found that on in Oracle Tech Tips:

Oracle Corp. recommends using the following RAID levels for different components of an Oracle 9 or 10 installation:

* Operating system -- RAID 1.
Oracle suggests using RAID 1 (mirroring) for the disk holding the operating system and Oracle binary files. In the event of failure, it's much easier to restore the OS and binaries than to rebuild the volume using something like RAID 5. This cuts down the time necessary to restore the system.
* Redo log files -- RAID 1 or RAID 10.
These files are sequential rather than random, so RAID 1 or RAID 10 (striping and mirroring) provide better performance than RAID 5 (striping with distributed parity). These files are also small enough that the higher cost of RAID 10 isn't a major factor.
* Data files -- RAID 5 or RAID 10.
The key here is a combination of cost and ratio of reads to writes. RAID 5 is significantly less expensive than RAID 10, but because of the differences in write performance, RAID 5 extracts a performance penalty. Oracle recommends using RAID 10 if fewer than 90% of the I/O operations are reads. If more than 90% of the operations are reads, then RAID 5 is an acceptable option. Of course, because of the cost penalty associated with RAID 10 (the need for twice the disk capacity as the amount of data storage), some installations will go with RAID 5 for cost reasons and accept the performance hit.
* Archive log files -- RAID 10 or RAID 5
. Here again, RAID 10 will give better performance, but the penalty associated with RAID 5 in writing and rebuilding a failed drive may be slight enough that RAID 5 is acceptable.

Hope this helps

[Jack Fan]

From IOPS point of view, Which raid mode (RAID 1+0 or RAID 5) able to provide higher IOPS on DL380 with my spec?

[David Claypool]

RAID 1+0 will always have superior performance. When you need to write in RAID 1+0, you just write the same data to both (sets of) disks. A write on RAID 5 means that you have to read all disks, write the track with the data, compute the new parity and write the parity. Reads won't have as much of a penalty.

[Jack Fan]

David,

Yes, I understand what you say. But I still want to know that how to calculate the total IOPS with RAID 1+0 or RAID 5 on my HP-DL380G4+72GB(15krpm)*6.

However, I am appreciate your answer, and give you 3 point.

Jack Fan