GeoWebCache: Is there a way to empty the cache only for a certain zoom level?

Question

This is a follow-up to this question. In short, I was overambitious in seeding and now my /usr filesystem is full. Take a look at the cache occupancy broken down by zoom level. (Data is OSM South America slice by Geofabrik, imported by osm2pgsql.)

[root@opengeosa opengeo_southamerica]# du -sk EPSG_900913*
4       EPSG_900913_00
8       EPSG_900913_01
16      EPSG_900913_02
36      EPSG_900913_03
236     EPSG_900913_04
832     EPSG_900913_05
3236    EPSG_900913_06
11088   EPSG_900913_07
32828   EPSG_900913_08
110464  EPSG_900913_09
392380  EPSG_900913_10
1487876 EPSG_900913_11
5303356 EPSG_900913_12
20030184        EPSG_900913_13
15776620        EPSG_900913_14
8828    EPSG_900913_15
189778220       EPSG_900913_16
7932    EPSG_900913_17
3764    EPSG_900913_18
492     EPSG_900913_19
200     EPSG_900913_20
352     EPSG_900913_21
[root@opengeosa opengeo_southamerica]# 

So, I would like to empy the misbegotten level 16 cache and leave all others. Is this doable? Could I just rm -rf EPSG_900913_16/* or would that be a Very Bad Thing™? Or should I just empty the entire cache and reseed only through level 14?

Answer 1

You should be able to do this easily through the web interface (ie http://yourserver:8080/geoserver/web). First log in, go to Tile Layers under the Tile Caching heading (left side).
One there, click on 'Seed / Truncate' next to the layer you are concerned with. You can set the parameters of the seed/truncate towards the bottom on that window. Most importantly:

• Type of Operation = Truncate
• SRS = EPSG:900913
• Zoom Start = 16
• Zoom End = 21

That should truncate (empty) all of the tiles cached in zoom levels 16-21 for EPSG:900913.