[gpfsug-discuss] File_heat for GPFS File Systems

[Eric Horst]

>>
>> if a file gets hot again, there is no rule for putting the file back
>> into a faster storage device?
>
>
> The file will get moved when you run the policy again.  You can run the
> policy as often as you like.

I think its worth stating clearly that if a file is in the Thrifty
slow pool and a user opens and reads/writes the file there is nothing
that moves this file to a different tier. A policy run is the only
action that relocates files. So if you apply the policy daily and over
the course of the day users access many cold files, the performance
accessing those cold files may not be ideal until the next day when
they are repacked by heat. A file is not automatically moved to the
fast tier on access read or write. I mention this because this aspect
of tiering was not immediately clear from the docs when I was a
neophyte GPFS admin and I had to learn by observation. It is easy for
one to make an assumption that it is a more dynamic tiering system
than it is.

-Eric

--
Eric Horst
University of Washington