Intel 1520 ユーザーズマニュアル

ページ / 176
Appendix A Caching Solutions and Performance
141
Two types of clusters are supported: soft clusters and management-only clusters. 
A soft cluster consists of multiple appliances that use an external clustering 
device such as an L4 Switch or router to handle load balancing and routing 
responsibilities. A management-only cluster also consists of multiple appliances 
whose functions are managed through a proprietary communications protocol 
accessible through the Manager UI. A management-only cluster does not use an 
external clustering device. 
Transparency
The Intel NetStructure Cache Appliance can transparently intercept NNTP traffic 
bound for a well known NNTP server. By transparently intercepting, caching, 
and serving the NNTP data from a centralized parent news server, the appliance 
simplifies migration and administration while both increasing responsiveness and 
decreasing network use.
Posting
The Intel NetStructure Cache Appliance sends user article postings to the parent 
news server. You can specify the parent news server that receives postings for a 
particular group or set of groups from the command-line interface. For 
procedural information, see Configuring NNTP servers‚ on page 65. When acting 
as the news server (accepting article feeds), the appliance accepts postings.
With background posting, the appliance queues posted articles until the posting 
news server can accept the posted article.
Maintaining the cache: updates and feeds
The Intel NetStructure Cache Appliance can maintain the freshness of its cache 
by:
✔ Updating its cache on demand
✔ Actively retrieving (pulling) updates at configured intervals
✔ Accepting news feeds 
You can configure the following options from both the Manager UI and the 
command-line interface:
Pull the overview information for specified groups:
For all groups designated as pullover, the server will retrieve the overview 
database information (using the 
OVER
/
XOVER
 commands) automatically and 
periodically. Pulling overview information can be useful for high volume 
groups that are frequently read but from which only a subset of the articles 
are accessed.