> Anyone in the know have any recommendation. From looking at the MESS SVN, there are
> still fixes coming in.
> The conversion time and required disk space are not the issue. I simply don't want to
> destroy any necessary data.
> Any help would be appreciated.
Unless you do something silly like using the same filename for input and output (which would overwrite your file), there is no way to destroy necessary data. the worst it can happen is that chdman crashes or hangs and no v5 CHD is created, so that you remain with your v4 CHD only. if the conversion/copy ends successfully and you want to be over-paranoid, just run "chdman verify -i your_new.chd" to see if the new chd is fine
Remember anyway that if you update the CHD they won't work on older MAME versions
For the record, all the fixes you saw in MESS svn were to fix creation of new blank CHDs for use as HDs in computer emulation. Possibly, there will be more fixes to avoid current random hangs, but as stated above the 0.145u1 code already produces perfectly stable CHDs when the process completes fine.