Chapter 7. Best practices for DB2 v10 during live guest relocation 71
ITSOLNX2) with share values of 600 and 400, respectively. And in the ITSOSS2 cluster we
have two guests (ITSOLNX3 and ITSOLNX4) with 700 and 300, respectively.
Initial share setting for ITSOSSI1 and ITSOSSI2
If a virtual guest (ITSOLNX11) has a relative share of 600 on z/VM Cluster1 (ITSOSSI1), the
normalized IFL allocation would be around one-fourth of the access to system resources in
ITSOSII1. And the second virtual guest (ITSOLNX2) has a relative share of 400, where
ITSOLNX2 would receives a quarter as much access to system resources as ITSOSSI1. See
Table 7-1.
Table 7-1 Initial share setting
Now relocate ITSOLNX1 to the target z/VM Cluster ITSOSSI2. This would alter the overall
sharing of resources setting in the guests. As in Table 7-2, it is evident that the access to
system resources for the ITSOLNX1 guest after relocation has doubled the percent of
resources shared that it had in the previous cluster.
Table 7-2 After relocation of guests - Share setting
Always review the target system share settings prior to the relocation of any DB2 servers.
7.3 Memory considerations
When defining memory requirements for virtual Linux guests, remember that the Linux kernel
will use all the extra available memory allocated to it as a file system cache. In a shared
resource environment such as z/VM, this causes the memory resource to be consumed in the
LPAR. Such cases could cause a negative impact greater than the positive impact of I/O
avoidance, which is especially true in configurations in which data is shared heavily between
virtual servers and is mostly read. Therefore, it is important to assign only the memory
needed for the running applications when they are at peak load.
10001000
0.420.00200ITSOLNX4
0.840.00400ITSOLNX2
1.680.00800ITSOLNX3
1.260.00600ITSOLNX1
Normalized
resource for
Guest
Share %
for Guest
z/VM Share
Relative
Guest
Normalized
resources
for Guest
Share %
for Guest
z/VM Share
Relative
Guest
ITSOSSI2
Cluster
ITSOSSI1
Cluster
10001000
0.420.00200ITSOLNX4
0.840.00400ITSOLNX2
1.680.00800ITSOLNX3
1.260.00600ITSOLNX1
Normalized
resource for
Guest
Share %
for Guest
z/VM Share
Relative
Guest
Normalized
resources
for Guest
Share %
for Guest
z/VM Share
Relative
Guest
ITSOSSI2
Cluster
ITSOSSI1
Cluster
1600
0.837.50600ITSOLNX1
400
0.733.33200ITSOLNX4
2.0100.00400ITSOLNX2
1.050.00800ITSOLNX3
ITSOLNX1
(Relocated)
Normalized
Resources
for Guest
Share % for
Gues t
z/VM Share
Rel a t i ve
Guest
Normalized
resources
for Guest
Share % for
Guest
z/VM Share
Rel a t i v e
Gues t
ITSOSSI2
Cl uster
ITSOSSI1
Cl uster
1600
0.837.50600ITSOLNX1
400
0.733.33200ITSOLNX4
2.0100.00400ITSOLNX2
1.050.00800ITSOLNX3
ITSOLNX1
(Relocated)
Normalized
Resources
for Guest
Share % for
Gues t
z/VM Share
Rel a t i ve
Guest
Normalized
resources
for Guest
Share % for
Guest
z/VM Share
Rel a t i v e
Gues t
ITSOSSI2
Cl uster
ITSOSSI1
Cl uster
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