Tablespace Available Used VS Allocated Used

Hello,

I'm using Oracle database 19c with ASM and RAC.

We are experienced some erros like this:

ORA-1691: unable to extend lobsegment USER1.SYS_LOB0000166124C00004$$ by 1024 in tablespace TS_USER1

When i checked the tablespace there are like 20GB free. After adding some more space to the datafile the error stops.

I first though about fragmentation, but after some scripts i saw there are enough free blocks and there is no fragmentation.

Finally I checked the tablespace in Enterprise Manager and realized that the "Avalialbe Sapce Used %) is 84,10 but the "Allocated Space Used %" is 97,55. So I think the problem is that there is not enough allocated free space. All others tablespaces has same value for available and allocated