data for the buckets is not deleted after uninstall couchbase

steps:
install 2.5.0-1059 on centos64 and create some buckets

[root@localhost ~]# ls -la /opt/couchbase/var/lib/couchbase/data/beer-sample/
total 12348
drwxrwx--- 2 couchbase couchbase 36864 Feb 18 00:21 .
drwxrwx--- 6 couchbase couchbase 4096 Feb 18 00:19 ..
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:19 0.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1000.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1001.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1002.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1003.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1004.couch.1

uninstall cb and check bucket's folder

[root@localhost ~]# rpm -e couchbase-server
Stopping couchbase-server
warning: /opt/couchbase/var/lib/couchbase/config/config.dat saved as /opt/couchbase/var/lib/couchbase/config/config.dat.rpmsave
warning: /opt/couchbase/etc/couchdb/local.ini saved as /opt/couchbase/etc/couchdb/local.ini.rpmsave

[root@localhost ~]# ls -la /opt/couchbase/var/lib/couchbase/data/beer-sample/
total 12348
drwxrwx--- 2 couchbase couchbase 36864 Feb 18 00:21 .
drwxrwx--- 6 couchbase couchbase 4096 Feb 18 00:19 ..
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:19 0.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1000.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1001.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1002.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1003.couch.1
rw-rw--- 1 couchbase couchbase 8238 Feb 18 00:20 1004.couch.1

All data for the buckets is still on the disk