what is the difference between VM4.0 and VM4.1 in terms of how DMP works?
I am new to DMP environment and need to participate in an effort to migrate
from VM4.0 to VM4.1. Could someone give me a brief idea of the differences
between them in terms of how DMP works?
Thanks a lot
Re: what is the difference between VM4.0 and VM4.1 in terms of howDMP works?
The biggest difference between 4.0 and 4.1 with regards to DMP, is that
4.1 support Third Party Devices (TPD).
So what does that mean in english ?
Best is to descibe with an example:
Version 4.0 if you have powerdevices (which means that you will have
powerpath installed). Now, DMP will do a bit of calculation to figure
out how to split the IO (to spread the load) and a bit of calculation to
determine if both the paths are alive, and will then do the IO.
PowerPath will intercept the IO, start it's own calculations and
eventually send the IO to the disk.
So we have 2 pieces of DMP software doing calculation (and thus taking a
bit of time), before the IO goes to the disk.
The other thing is that in Version 4.0, you have to tell Volume Manager
about the foreign devices.
Now, 4.1 with the new Array Support Library (ASL) will know what
powerdevices are, and will allow the third part driver (PowerPath) to do
Appart from that, there is the normal bug fixes that goes into later
versions (having said that, 4.0MP1 and MP2 contains more fixes than 4.1)
> I am new to DMP environment and need to participate in an effort to migrate
> from VM4.0 to VM4.1. Could someone give me a brief idea of the differences
> between them in terms of how DMP works?
> Thanks a lot