I started to Dissolve a moderately-large (~31,507 arcs) multi-attribute feature class some 20 hours ago. It's still running, entirely in memory (no file updates in the target geodatabase). How long should this take? When should I cancel processing because it will never complete? How might I speed up this processing?
ArcMap 10.1 SP1 for Desktop, build 3143
Dell Precision T3600, Intel Xeon 3.6 GHz CPU, 32 GB RAM, 64-bit Windows 7
For future reference... since I presume that you found out via the help that it can take a long time and there are some suggestions in the help to speed things up
Dissolve—Help | ArcGIS for Desktop
specifically the link on processing large datasets
Tiled processing of large datasets—Help | ArcGIS for Desktop