Optimizer swapping the same two volumes over and over

Question

I run optimizer on saturday/sunday for a DMX.

This DMX normally does 20 or so swaps.

The last three times this has run it only shows continual swaps for volumes 423 and 44E.

example:

volume 423 swaps from DF16C: D6 H9 to DF16C:C15 H22

volume 44e swaps from DF16C: C15 H22 to DF16C: D6 H9

volume 423 swaps from DF16D:C6 H9 to DF16D:D15 H22

volume 44e swaps from DF16D:D15 H22 to DF16D:C6 H9

This continues for 24 swaps and then the optimizer job ends.

Can some one give me an idea as to why this may be occuring and no other swaps are being done?

Thank you in advance for your help.

srichev · Answer

Optimizer is balancing the load on your box.Ideally if you have a unmapped(free) symdevs/less utilized symdev,busy symdevs will be swapped there.

In your case,423 would have more IO load compared to 44e and they would have set of two different spindles.it's swapping the volumes and balancing the load.

If you look at clearly in your log it's using DRV drives in between to swap.Refer to any optimizer document/white paper this has been explained.let me know if you do not find one.

Sammie4 · Answer

Hello Srichev,

I had EMC check Optimizer and they found that it was hung.

They cleared it and rebooted the service processor.

Thank you for responding.

Best regards,

Samantha St.John

VOLVO INFORMATION TECHNOLOGIES

Senior Storage Engineer

7821 National Service Road

Greensboro, NC 27402

Phone: (336)393-3917

Fax: (336)393-4080

Email: samantha.st.john@volvo.com

Mail drop: AP3/46

MikeMac1 · Answer

Are devices 423 and 44e RAID devices? For example, say that they are both 8 member RAID 5 devices you would have 8 different members on 8 different physical devices. Looking at this, the first swap between devices 423 and 44e were between different physical disks that reside on DAF 16 on the C processor (DF16C) and when you look at the second swap you can see that now it's working on the physicals disks that reside on DAF 16 D processor (DF16D).

volume 423 swaps from DF16C: D6 H9 to DF16C:C15 H22
volume 44e swaps from DF16C: C15 H22 to DF16C: D6 H9
volume 423 swaps from DF16D:C6 H9 to DF16D:D15 H22
volume 44e swaps from DF16D:D15 H22 to DF16D:C6 H9

Sammie4 · Answer

Yes.....they are raid devices.