DO vs System Tuner

[dlee]

Hi all,

What are the differences between DO and System Tuner (besides DO can move LUN across different tier/CPG)? Looking at the explanation it seems both are used to rebalance data especially after we do disk upgrade. Can it be done automatically, especially for P10000?

If I add 600GB disks into existing 3PAR with all 300GB disks, how will the rebalance work? The 600GB will hold more used chunklets after rebalancing?

Thanks,
DL

[uhammer]

System Tuner was created to combat FUD other vendors were throwing about hot-spots on disks being shared by applications. What system Tuner does is look at the busy disks, then look at the busy Chunklets then move those busy Chunklets to less busy disks. Cool concept but the reality it isn't solving a problem in 3PAR world because hot-spots don't develop. over time and many iterations System Tuner would normalize IO accross all the disks. However it would be a many iterations to accomplish.

Dynamic Optimization is a different beast. It has two modes. One is to change the layout of a volume from one thing to another. SayR6 to R1 or FC to SSD, etc. You can go from anything to anything. Second is to restripe accross new resources. It looks at how evenly distributed your system is and will redistribute if it isn't very even. Simple enough.

[dlee]

Thanks for the explanation. Is it correct to say that with DO I can also eliminate hotspot by choosing "Tune Volume"? By restripe and evenly distribute chunklets, in a way I remove hotspots.

[Richard Siemers]

Not "hot spots"... DO will allow you to correct provisioning mistakes such as:

Moving a Oracle Redo Log LUN from a SATA raid5 to a FC raid1.
Or
Moving a developement LUN off of your SSD's and down to SATA.

DO basically moves a lun from 1 CPG to another.