ISPPlanet Cache Review Series - CacheFlow 545

Viewing Cache Performance
The Statistics applet serves as the CacheFlow's dashboard: pie charts, histograms, and raw data provide insight into traffic volume, disk/memory usage, cache efficiency, and stored content. Statistics are cumulative, with a single "Clear Stats" reset button—we prefer this to GUIs that lose history on reboot.

Volume (below, left) presents histograms that measure objects, bytes, clients, CPU, and freshness during the last hour, day, and month. Efficiency (below, right) uses a pie chart to show distribution of objects or bytes served as from the cache, loaded from source, or non-cacheable.
Volume panel	Efficiency panel
Others pie charts break down non-cacheable content and contrast RAM vs. disk hits, while a third panel substantiates all charts with raw data (below, left). One metric we haven't yet seen in other products is the histogram showing Content distribution (below, right). Knowing the size of previously-stored objects can be helpful when tuning max HTTP and FTP object size.
Efficiency: Data tab	Contents: Distribution tab

The Statistics applet also includes a General page that summarizes the current configuration and provides operational status: temperature, fan, power, and disk. We did not spot a network health monitor that might show adapter status or gateway / DNS reachability, but significant network events can be seen using the Event Viewer (see Advanced Monitoring).

Like other products, the CacheFlow logs client requests, but it does so with a few twists. The log file must be uploaded to a primary or alternate FTP server on a scheduled basis: daily, hourly, on demand, or based on percent of available disk used (below, left). There is no provision to "tail" the log while still on the cache, or to store multiple logs on the cache. CacheFlow uses NCSA Common Log Format by default, with Squid Format as an option, but also parses a well-defined syntax to yield Custom Formats (below, right).

Log entries indicate more than HIT or MISS: they also signal object expiration, forced refresh, filter/bypass blocking, and how responses are obtained (e.g., direct from server, via ICP parent or sibling). Customization can be handy to reduce the space consumed and focus on what is most relevant to you.