INFO: Caching mechanisms in Index Manager 7.0 Service Release 4

The information in this article applies to:

• Index Manager 7.0 Service Release 4 (build 500 and newer)

SUMMARY

This document aims to explain how the caching mechanisms in Index Manager 7.0 SR4 work. It is intended for system administrators, not users of FotoWare client software.

 

MORE INFORMATION

A FotoWare system requires Index Manager to generate browseable thumbnails and previews of the files in your indexed archives.

 

To increase the speed with which FotoWare clients can access and display the thumbnails and previews, Index Manager uses a caching mechanism. You can set the location of the cache folder in the Index Manager’s Service Options in the Operations Center.

 

The index folder should be stored on the fastest disk available in your system, and that disk should have a large cache to improve performance. You should never store the cache on a volume that the Index Manager needs to access over a network.

 

When a user requests a file that is not available in the cache, Index Manager generates a thumbnail and preview of that file, whether it’s an image file, a PDF or an Office document, and serves it to the client over the FWP protocol. It will also store a copy of the thumbnail and preview in the cache folder for future use. Up until Service Release three, this was the only caching mechanism in Index Manager, and it could result in thumbnails taking a little while to display at a client’s workstation. All in all, it depended on the time it took for Index Manager to generate the thumbnail.

 

With Index Manager 7.0 Service Release 4 (builds 500 and newer) the caching mechanism has been improved further. When the service starts up, it will initialize the indexes and make them available to the clients, after which it starts a cache warming process. This implies that Index Manager scans the index’ document folders and pre-generates thumbnails and previews and stores them in the cache. Thus, chances are Index Manager can use a cached copy of a file that a client requests without having to generate it on-request. This has proven to greatly improve the speed of most systems, even ones that don’t have a great deal of traffic, although high-volume systems will notice the biggest performance boost.

 

In Index Manager’s Service Options, you find a setting that controls the size of the cache per index. This setting relates to the caching outlined above. It sets the maximum size that Index Manager will let the cache expand to before it shuts down the cache warming, i.e. the pre-generation of thumbnails and previews. When clients request files that are not cached, Index Manager will still cache them on-request for future use, so the cache folder may still expand beyond the preset size that you have defined. Then, when the index is optimized (typically at non-operating hours using a preset optimization schedule), Index Manager deletes the cached items for files that have been deleted from the document folders. If at this point the cache folder size still exceeds the maximum size set in the Service Options, the cache will be reduced to 80% of that volume by purging the oldest items from the cache.

A note to updaters from Service Release 3

When you update from an Index Manager 7.0 Service Release 3 to Service Release 4, you will notice that the cache from the SR3 installation remains even after the SR4 version has run its cache purging routines as described above. Hence, it’s good practice to delete the contents of the cache folder after updating to SR4 and then letting the new Index Manager build its cache automatically.