VMware CLOUD DIRECTOR 1.0 Instrukcja Użytkownika Pobierz pdf (Strona 26)

PERFORMANCE STUDY /26

VMware vCloud Director 1.0 Performance and Best Practices

managed by it, the above sizing formula still holds.

An additional detail that you should pay attention to is the JVM heap size for each vCloud Director cell process.

As mentioned previously, an increase in the total number of inventory items cached requires more memory on

each cell. So, it is essential to increase the JVM heap equivalently. By default, JVM heap size is configured to be

1GB for the process. This is good for supporting 5000 inventory cache entries. If the number of cached entries is

changed, for example, to 15,000 (an additional 10,000) for a large vCloud Director installation, you might need to

increase the JVM heap size to support additional cache entries. In this example, the JVM heap size should be

increased to 1.5GB (1GB original + 10,000 x 30KB = 300MB + 200MB as some buffer for other caches/objects with

an increase in total VMs) to support the additional 10,000 cache entries per vCloud Director cell.

For large installations, if the JVM heap size is not increased, it is likely that the vCloud Director cell will run out of

memory, resulting in poor performance and a possible cell failure. For more information, refer to knowledge base

article 1026355 to change vCloud Director JVM Heap size

[9].

Inventory Sync Resource Consumption

During inventory sync, up to 25% out of 4 vCPUs can be consumed because inventory sync is implemented as a

single thread task. For the vCloud Director database, reconnect-vCenter-sync consumes the least CPU among all

three types of syncs because most objects are held in the inventory cache, and there is no need to query and

insert the backend database. For initial sync and restart-cell-sync, the Oracle database consumes less than 20%

of 4 vCPUs. As we have discussed, most of the CPU usage is consumed by database inserts in the initial sync

case. However, for restart-cell-sync, most of the CPU consumed is for database queries.

All three types of syncs depend on vCenter Server to provide the inventory information. As the number of

inventory objects gets bigger, the resource consumption in vCenter Server is more significant. Figure 23 shows

vCenter Server CPU usage for reconnect-vCenter-sync with a different number of VMs.

Figure 23. vCenter CPU Usage for Reconnect-vCenter-Sync with 1000, 2000 and 3000 VMs

100

120

Percentage of 4 vCPU (400%) Used

Sample Points Every 5 Seconds

3000 VMs

2000 VMs

1000 VMs

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VMware CLOUD DIRECTOR 1.0 Instrukcja Użytkownika Strona 26