9.14 SmartBlobs/No free disk space error

I have defined a temporary smart blob space of significant size, and normally my queries that create smart large objects have no problem. But periodically I start getting an error 9810 Smart Blobs Error accompanied by a "No free disk space" error. When I do an "onstat -d" I see that the free space in the temp sblobspace is about 75%. In fact I monitor this free space in one window while I do my query in the other. The free space does shrink as the query runs, but it never gets below 75%. The problem goes away as soon as I drop and recreate the sblobspace. I'm wondering if the problem is that I haven't defined the metadata section to be large enough. Is there any way to monitor the amount of free space in the metadata section? Are there any guidelines on sizing the metadata section for temp smart blob spaces? Any help would be greatly appreciated! Thanks,.. Mike