User Guide

Chapter 10. The DS Storage Manager - logical configuration 197
Figure 10-5 shows an example of the relationship between LSSs, extent pools, and volume
groups: Extent pool 4, consisting of two LUNs, LUN 2210 and LUN 7401; and extent pool 5,
consisting of three LUNs, LUN 2313, 7512, and 7515.
Here are some considerations regarding the relationship between LSS, extent pools, and
volume groups:
򐂰 Volumes from different LSSs and different extent pools can be in one volume group as
shown in Figure 10-5. Volume group 1 consists of extent pool 4, LUN 2210, and extent
pool 5, LUN 7512.
򐂰 Volumes from the same LSS or the same extent pool, or both, can be in different volume
groups. For example in Figure 10-5, LUN 7512 in extent pool 5 and LUN 7515 in extent
pool 5, both of which reside in LSS75, also reside in different volume groups.
Figure 10-5 Example of relationship between LSSs, extent pools, and volume group
The LSS and LCU provide the logical grouping of volumes/LUNs for Copy Services and
various other purposes. Some of these purposes are explained along with general
considerations about LSSs in the DS8000, as follows:
򐂰 The LSS or LCU determines the addressing, address groups, and PAVs.
– Each logical volume has a 4 digit Hexadecimal xyzz identification number built using
the following rules: x = the address group, xy = LSS number itself, and zz = the volume
id (volid). For example, LUN 2310 has an address group number of 2, is located in LSS
23, and has a volid of 10.
– There are up to 16 LSSs in an address group. For example, 00 to 0F for address group
0, 10-1F for address group 1, 20-2F for address group 2, and so forth.
– Any given PAV can only be used within one LCU.
򐂰 LSSs are used for Copy Services, PPRC paths, and consistency group properties or
time-outs.
򐂰 There are a maximum number of LSSs. For the DS8000 there are a maximum of 255
LSSs. When speaking of ESCON, the maximum is 16 ESCON CKD LSSs.
򐂰 The LSSs have a pre-determined association with Server0 or Server1.
– The even LSSs are associated with Server0.
– The odd LSSs are associated with Server1.
򐂰 The LSSs are configured to be either CKD or FB.
– CKD LSSs’ definitions are configured during the LCU creation.
2
2
1
0
7
4
0
1
Extent Pool 4 Extent Pool 5
Volume Group 1
Volume Group 2
2
3
1
3
7
5
1
2
7
5
1
5