will changing settings "prefetch" and "array mode" help?

[Sviatoslav Rimdenok]

Hello All!

we have got HP VA7400 array running HP18 firmware. It is occupied with 15x72GB disks.
We have problem with performance - I know that adding more disks (i.e. adding disk enclosure) helps, but we don't have such possibility.
Arrays operates in AutoRAID mode - I got some data from armperf and imported them into exceel sheet. Looks like only 10-15% of data are stored as RAID1+0.
I also noticed that during the times we had bad perfomance (data processing) - I could see high values of Forced Unit Access values (taken from armperf).
I checked documentation and looks like our array is working in "secure mode" :
Simplified Resiliency Setting:________Secure (High Recoverability)
Performance Goal Configuration:_______High Recoverability (Secure)

Could you please tell me if changing to "normal mode" will help improve perfomance? Do I need to reset array to implement that setting or can it be done on-the-fly?

I have also another setting which could be tuned - "enable prefetch". Currently it is disabled. But HP doc says that it could make perfomance worse sometimes. I would like to play with that setting as well - do I need to reset array to implement that setting?

By the way : what is a reason to run array in "secure mode"? As I understood there are batteries - so NVRAM will be written to disks anyway in case of power failure. Do I understand it correctly?

thank you in advance!

cheers,
Slava R.