IBM DS8882F, Introduction And Planning Manual

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Table 11. Comparison of features (continued)
Feature Description Advantages Considerations
z/OS Global Mirror Asynchronous copy
controlled by IBM Z
host software Nearly unlimited
distance, highly
scalable, and very
low RPO. Additional host
server hardware and
software is required.
The RPO might grow
if bandwidth
capability is exceeded
or host performance
might be impacted.
I/O Priority Manager
The performance group attribute associates the logical volume with a performance
group object. Each performance group has an associated performance policy which
determines how the I/O Priority Manager processes I/O operations for the logical
volume.
Note:
The default setting for this feature is “disabled” and must be enabled for
use through either the DS8000 Storage Management GUI or the DS CLI.
The I/O Priority Manager maintains statistics for the set of logical volumes in each
performance group that can be queried. If management is performed for the
performance policy, the I/O Priority Manager controls the I/O operations of all
managed performance groups to achieve the goals of the associated performance
policies. The performance group defaults to 0 if not specified. Table 12 lists
performance groups that are predefined and have the associated performance
policies:
Table 12. Performance groups and policies
Performance group
1
Performance policy
Performance policy
description
0 0 No management
1-5 1 Fixed block high priority
6-10 2 Fixed block medium priority
11-15 3 Fixed block low priority
16-18 0 No management
19 19 CKD high priority 1
20 20 CKD high priority 2
21 21 CKD high priority 3
22 22 CKD medium priority 1
23 23 CKD medium priority 2
24 24 CKD medium priority 3
25 25 CKD medium priority 4
26 26 CKD low priority 1
27 27 CKD low priority 2
28 28 CKD low priority 3
29 29 CKD low priority 4
30 30 CKD low priority 5
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DS8882F Introduction and Planning Guide