diff --git a/src/common/config_opts.h b/src/common/config_opts.h
index fa11c21ad5a..b07b6a7ed24 100644
--- a/src/common/config_opts.h
+++ b/src/common/config_opts.h
@@ -178,6 +178,7 @@ OPTION(mon_force_standby_active, OPT_BOOL, true) // should mons force standby-re
 OPTION(mon_warn_on_old_mons, OPT_BOOL, true) // should mons set health to WARN if part of quorum is old?
 OPTION(mon_warn_on_legacy_crush_tunables, OPT_BOOL, true) // warn if crush tunables are not optimal
 OPTION(mon_warn_on_osd_down_out_interval_zero, OPT_BOOL, true) // warn if 'mon_osd_down_out_interval == 0'
+OPTION(mon_warn_on_cache_pools_without_hit_sets, OPT_BOOL, true)
 OPTION(mon_min_osdmap_epochs, OPT_INT, 500)
 OPTION(mon_max_pgmap_epochs, OPT_INT, 500)
 OPTION(mon_max_log_epochs, OPT_INT, 500)
diff --git a/src/mon/OSDMonitor.cc b/src/mon/OSDMonitor.cc
index a8c2c64c6b4..415ae19c473 100644
--- a/src/mon/OSDMonitor.cc
+++ b/src/mon/OSDMonitor.cc
@@ -2078,6 +2078,32 @@ void OSDMonitor::get_health(list<pair<health_status_t,string> >& summary,
       }
     }
 
+    // hit_set-less cache_mode?
+    if (g_conf->mon_warn_on_cache_pools_without_hit_sets) {
+      int problem_cache_pools = 0;
+      for (map<int64_t, pg_pool_t>::const_iterator p = osdmap.pools.begin();
+	   p != osdmap.pools.end();
+	   ++p) {
+	const pg_pool_t& info = p->second;
+	if (info.cache_mode_requires_hit_set() &&
+	    info.hit_set_params.get_type() == HitSet::TYPE_NONE) {
+	  ++problem_cache_pools;
+	  if (detail) {
+	    ostringstream ss;
+	    ss << "pool '" << osdmap.get_pool_name(p->first)
+	       << "' with cache_mode " << info.get_cache_mode_name()
+	       << " needs hit_set_type to be set but it is not";
+	    detail->push_back(make_pair(HEALTH_WARN, ss.str()));
+	  }
+	}
+      }
+      if (problem_cache_pools) {
+	ostringstream ss;
+	ss << problem_cache_pools << " cache pools are missing hit_sets";
+	summary.push_back(make_pair(HEALTH_WARN, ss.str()));
+      }
+    }
+
     // Warn if 'mon_osd_down_out_interval' is set to zero.
     // Having this option set to zero on the leader acts much like the
     // 'noout' flag.  It's hard to figure out what's going wrong with clusters
diff --git a/src/osd/ReplicatedPG.cc b/src/osd/ReplicatedPG.cc
index 4dae5d3fef2..88d42c13c09 100644
--- a/src/osd/ReplicatedPG.cc
+++ b/src/osd/ReplicatedPG.cc
@@ -1348,9 +1348,10 @@ void ReplicatedPG::do_op(OpRequestRef& op)
 	hit_set_start_stamp + pool.info.hit_set_period <= m->get_recv_stamp()) {
       hit_set_persist();
     }
+  }
 
-    if (agent_state)
-      agent_choose_mode();
+  if (agent_state) {
+    agent_choose_mode();
   }
 
   if ((m->get_flags() & CEPH_OSD_FLAG_IGNORE_CACHE) == 0 &&
@@ -11342,7 +11343,8 @@ bool ReplicatedPG::agent_maybe_evict(ObjectContextRef& obc)
     }
   }
 
-  if (agent_state->evict_mode != TierAgentState::EVICT_MODE_FULL) {
+  if (agent_state->evict_mode != TierAgentState::EVICT_MODE_FULL &&
+      hit_set) {
     // is this object old and/or cold enough?
     int atime = -1, temp = 0;
     agent_estimate_atime_temp(soid, &atime, NULL /*FIXME &temp*/);
@@ -11474,7 +11476,11 @@ void ReplicatedPG::agent_choose_mode(bool restart)
       num_dirty = 0;
   }
 
-  dout(10) << __func__ << ": "
+  dout(10) << __func__
+	   << " flush_mode: "
+	   << TierAgentState::get_flush_mode_name(agent_state->flush_mode)
+	   << " evict_mode: "
+	   << TierAgentState::get_evict_mode_name(agent_state->evict_mode)
 	   << " num_objects: " << info.stats.stats.sum.num_objects
 	   << " num_bytes: " << info.stats.stats.sum.num_bytes
 	   << " num_objects_dirty: " << info.stats.stats.sum.num_objects_dirty
diff --git a/src/osd/osd_types.h b/src/osd/osd_types.h
index a311e651885..abbfe2c2675 100644
--- a/src/osd/osd_types.h
+++ b/src/osd/osd_types.h
@@ -876,6 +876,19 @@ struct pg_pool_t {
   const char *get_cache_mode_name() const {
     return get_cache_mode_name(cache_mode);
   }
+  bool cache_mode_requires_hit_set() const {
+    switch (cache_mode) {
+    case CACHEMODE_NONE:
+    case CACHEMODE_FORWARD:
+    case CACHEMODE_READONLY:
+      return false;
+    case CACHEMODE_WRITEBACK:
+    case CACHEMODE_READFORWARD:
+      return true;
+    default:
+      assert(0 == "implement me");
+    }
+  }
 
   uint64_t flags;           ///< FLAG_*
   __u8 type;                ///< TYPE_*
diff --git a/src/vstart.sh b/src/vstart.sh
index 6ba2995ecfa..1cf4dbe56a6 100755
--- a/src/vstart.sh
+++ b/src/vstart.sh
@@ -381,6 +381,12 @@ $DAEMONOPTS
         osd class dir = .libs
         osd scrub load threshold = 5.0
         osd debug op order = true
+        filestore wbthrottle xfs ios start flusher = 10
+        filestore wbthrottle xfs ios hard limit = 20
+        filestore wbthrottle xfs inodes hard limit = 30
+        filestore wbthrottle btrfs ios start flusher = 10
+        filestore wbthrottle btrfs ios hard limit = 20
+        filestore wbthrottle btrfs inodes hard limit = 30
 $COSDDEBUG
 $COSDMEMSTORE
 $extra_conf