Re: Question on gathering System Statistics

A key question to ask first is whether you had system stats set/collected on the vmax250 and whether this was done in combination with setting the db_file_multiblock read count or leaving it to default, and had you done anything with the calibrate_io option?
Ideally you probably want to believe that if you get the same plans with the Powermax you'll get the same, or better, performance. But if you do something that changes the optimizer's arithmetic you may get plan changes that result in random variations in performance.

If you don't know what you've done about system stats in the past there's a script at the end of this blog note that will report them for you: https://jonathanlewis.wordpress.com/2019/08/14/gather_system_stats/

Regards
Jonathan Lewis

On Tue, 26 Jan 2021 at 19:30, Hameed, Amir <Amir.Hameed_at_xerox.com> wrote:

> Hi,
>
> We are in the process of moving our applications from current storage
> array (VMAX250) to a new array (Powermax). From best practices standpoint,
> should we collect System Stats after moving to the new storage? If we
> should then is there a recommended way of gathering System Stats?
>
>
>
> Thanks,
>
> Amir
>

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