/dev/mapper/pgdatavg-base 138304552 131262788 16384 100% /var/lib/pgsql/data/base
pg_xlog is on a separate volume, and it's got plenty of space.
[postgres@fpslbxmbstgl05 ~]$ psql TAP553 -c "drop index idx_log_attr_source;" WARNING: could not create relation-cache initialization file "base/16384/pg_internal.init.32736": No space left on device DETAIL: Continuing anyway, but there's something wrong. DROP INDEX
drop table throws a similar error.
What can I do besides restore from backup?