In versions prior to Content Manager OnDemand v9.5, 'arsadmin' was a utility that did the majority of the work during the ingestion of data with arsload. It was responsible for compressing, segmenting, inserting metadata, and storing objects and resources into the cache, Tivoli Storage Manager, and the database engine. It was also the way that administrators could unload data from CMOD in case data needed to be removed from the system.
In CMOD v9.5 and higher, much of the functionality from the arsadmin command has been integrated into the arsload in order to improve performance by minimizing forking additional processes. This allows more concurrent data ingestion to occur with less CPU overhead, and less wait time.
Links to IBM Documentation
Estimating Compression Sizes
You can use the arsadmin compress command to test the effective compression ratios of the different compression methods that CMOD offers. In the overwhelming majority of cases, OD77 will provide the best compression / smallest files.
Choosing the best compression method
By using the IBM CMOD arsadmin command multiple times with the different compression methods (LZW16, OD77 OD77Lite) you can determine the best compression method for a specific type of document that will be stored in CMOD.
- This compression method is based on the Lempel-Ziv-Welch compression method, similar to the .ZIP file format. It is fast, but offers relatively low compression.
- The OD77 compression method is proprietary to IBM Content Manager OnDemand. It provides the best compression ratio, at the expense of consuming a lot of CPU time, which means loading data into IBM CMOD with this method is slower than other methods.
- This is essentially the same as OD77, but allows for faster load times by sacrificing compression ratio.