Serv er 0, Serv er1, Rank – IBM DS8000 User Manual

Page 112: Groups

DS8000 Series: Concepts and Architecture

The DS Storage Manager GUI guides the user to use the same RAID types in an extent pool.
As such, when an extent pool is defined, it must be assigned with the following attributes:

– Server affinity
– Extent type
– RAID type

The minimum number of extent pools is one; however, you would normally want at least two,
one assigned to server 0 and the other assigned to server 1 so that both servers are active. In
an environment where FB and CKD are to go onto the DS8000 storage server, you might
want to define four extent pools, one FB pool for each server, and one CKD pool for each
server, to balance the capacity between the two servers. Of course you could also define just
one FB extent pool and assign it to one server, and define a CKD extent pool and assign it to
the other server. Additional extent pools may be desirable to segregate ranks with different
DDM types.

Ranks are organized in two

rank

groups:

– Rank group 0 is controlled by server 0.
– Rank group 1 is controlled by server 1.

Figure 5-6 is an example of a mixed environment with CKD and FB extent pools.

Figure 5-6 Extent pools

You can expand extent pools by adding more ranks to an extent pool.

Important: You should balance your capacity between the two servers for optimal
performance.

1GB
FB

Serv

1113
Cyl.
CKD

Serv

er1

1113
Cyl.
CKD

1GB
FB

1113
Cyl.
CKD

1GB
FB

Extent Pool CKD0

Extent Pool CKD1

Extent Pool FBtest

Extent Pool FBprod