diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7bf432d4..83746a82 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## 3.0.4 (unreleased)
 
+- **dashboards**: PCP Vector Host Overview: add pmproxy URL and hostspec variables
+- **vector, bpftrace**: use `pcp://127.0.0.1` as default hostspec (no functional change)
 - **chore**: update dependencies
 - **test**: replace convey with testify for the Go tests
 
diff --git a/src/datasources/bpftrace/datasource.test.ts b/src/datasources/bpftrace/datasource.test.ts
index 6cb24367..d112a644 100644
--- a/src/datasources/bpftrace/datasource.test.ts
+++ b/src/datasources/bpftrace/datasource.test.ts
@@ -31,7 +31,7 @@ describe('PCP BPFtrace', () => {
     });
 
     it('should register a script and return the data', async () => {
-        const queries = [
+        const targets = [
             {
                 refId: 'A',
                 expr: '...cpuwalk...',
@@ -39,7 +39,7 @@ describe('PCP BPFtrace', () => {
             },
         ];
 
-        let response = await datasource.query(grafana.dataQueryRequest(queries));
+        let response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toEqual({ data: [] });
 
         mockNextResponses([
@@ -57,7 +57,7 @@ describe('PCP BPFtrace', () => {
         mockNextResponses([fetchResponse2]);
         await datasource.poller.poll();
 
-        response = await datasource.query(grafana.dataQueryRequest(queries));
+        response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect({ fields: response.data[0].fields }).toMatchInlineSnapshot(
             {
                 fields: [
@@ -245,14 +245,14 @@ describe('PCP BPFtrace', () => {
             Array [
               Object {
                 "params": Object {
-                  "hostspec": "127.0.0.1",
+                  "hostspec": "pcp://127.0.0.1",
                   "polltimeout": 11,
                 },
                 "url": "http://localhost:1234/pmapi/context",
               },
               Object {
                 "params": Object {
-                  "hostspec": "127.0.0.1",
+                  "hostspec": "pcp://127.0.0.1",
                   "polltimeout": 30,
                 },
                 "url": "http://localhost:1234/pmapi/context",
diff --git a/src/datasources/lib/pmapi/data_processor.test.ts b/src/datasources/lib/pmapi/data_processor.test.ts
index 63a8ee0a..d6c8f0bd 100644
--- a/src/datasources/lib/pmapi/data_processor.test.ts
+++ b/src/datasources/lib/pmapi/data_processor.test.ts
@@ -5,7 +5,7 @@ import { processQueries } from './data_processor';
 describe('data processor', () => {
     it('should create a dataframe and handle missing frames and backward counters', () => {
         const target = poller.target({ query: { expr: 'disk.dev.read' } });
-        const dataQueryRequest = grafana.dataQueryRequest([target.query]); // request data between 10-20s
+        const dataQueryRequest = grafana.dataQueryRequest({ targets: [target.query] }); // request data between 10-20s
 
         const values = [
             {
@@ -266,7 +266,7 @@ describe('data processor', () => {
         };
 
         const endpoint = poller.endpoint({ metrics: [metricA, metricB], targets: [targetA, targetB] });
-        const dataQueryRequest = grafana.dataQueryRequest([targetA.query, targetB.query]);
+        const dataQueryRequest = grafana.dataQueryRequest({ targets: [targetA.query, targetB.query] });
 
         const result = processQueries(
             dataQueryRequest,
@@ -359,7 +359,7 @@ describe('data processor', () => {
         };
 
         const endpoint = poller.endpoint({ metrics: [metric], targets: [target] });
-        const dataQueryRequest = grafana.dataQueryRequest([target.query]);
+        const dataQueryRequest = grafana.dataQueryRequest({ targets: [target.query] });
         const result = processQueries(dataQueryRequest, [{ endpoint, query: target.query, metrics: [metric] }], 1);
         expect(result[0].fields).toMatchInlineSnapshot(`
             Array [
diff --git a/src/datasources/lib/pmapi/datasource_base.ts b/src/datasources/lib/pmapi/datasource_base.ts
index 52925606..2c571c5e 100644
--- a/src/datasources/lib/pmapi/datasource_base.ts
+++ b/src/datasources/lib/pmapi/datasource_base.ts
@@ -19,7 +19,9 @@ import { MinimalPmapiQuery, PmapiDefaultOptions, PmapiOptions, PmapiQuery } from
 const log = getLogger('datasource_base');
 
 export abstract class DataSourceBase<Q extends MinimalPmapiQuery, O extends PmapiOptions> extends DataSourceApi<Q, O> {
+    /** URL as specified in the datasource settings page (can be undefined) */
     url?: string;
+    /** hostspec as specified in the datasource settings page, or default hostspec */
     hostspec: string;
     retentionTimeMs: number;
     pmApiService: PmApiService;
@@ -33,8 +35,19 @@ export abstract class DataSourceBase<Q extends MinimalPmapiQuery, O extends Pmap
     ) {
         super(instanceSettings);
         this.url = instanceSettings.url;
-        this.hostspec = instanceSettings.jsonData.hostspec ?? defaults.hostspec;
-        this.retentionTimeMs = interval_to_ms(instanceSettings.jsonData.retentionTime ?? defaults.retentionTime);
+
+        if (isBlank(instanceSettings.jsonData.hostspec)) {
+            this.hostspec = defaults.hostspec;
+        } else {
+            this.hostspec = instanceSettings.jsonData.hostspec!;
+        }
+
+        if (isBlank(instanceSettings.jsonData.retentionTime)) {
+            this.retentionTimeMs = interval_to_ms(defaults.retentionTime);
+        } else {
+            this.retentionTimeMs = interval_to_ms(instanceSettings.jsonData.retentionTime!);
+        }
+
         this.pmApiService = new PmApiService(getBackendSrv(), {
             dsInstanceSettings: instanceSettings,
             timeoutMs: apiTimeoutMs,
@@ -54,30 +67,48 @@ export abstract class DataSourceBase<Q extends MinimalPmapiQuery, O extends Pmap
     }
 
     getUrlAndHostspec(query?: Q, scopedVars: ScopedVars = {}): { url: string; hostspec: string } {
-        const url = getTemplateSrv().replace(query?.url ?? this.url ?? '', scopedVars);
-        const orInTheQueryErrorText = query ? ' or in the query editor' : '';
+        let url: string | undefined;
+        let hostspec: string | undefined;
+
+        // evaluate query settings first
+        if (query) {
+            if (!isBlank(query.url)) {
+                url = getTemplateSrv().replace(query.url);
+
+                if (this.url?.startsWith('/api/datasources/proxy') && !isBlank(url)) {
+                    // Grafana will send additional x-grafana headers to every request in browser mode, which make the CORS request fail
+                    throw new GenericError(
+                        'Please set the access mode to Browser in the datasource settings when using a custom pmproxy URL for this panel.'
+                    );
+                }
+            }
+            if (!isBlank(query.hostspec)) {
+                hostspec = getTemplateSrv().replace(query.hostspec);
+            }
+        }
 
-        if (this.url?.startsWith('/api/datasources/proxy') && !isBlank(query?.url)) {
-            // Grafana will send additional x-grafana headers, which make the CORS request fail
-            throw new GenericError(
-                'Please set the access mode to Browser in the datasource settings when using a custom URL for this panel.'
-            );
+        // if query is not defined (e.g. it's a dashboard variable query (metricFindQuery))
+        // or the url/hostspec of it evaluates to a blank string, use the datasource settings
+        if (isBlank(url)) {
+            url = this.url;
+        }
+        if (isBlank(hostspec)) {
+            hostspec = this.hostspec;
         }
 
+        const orInTheQueryErrorText = query ? ' or in the query editor' : '';
         if (isBlank(url)) {
             throw new GenericError(
                 `Please specify a connection URL in the datasource settings${orInTheQueryErrorText}.`
             );
         }
-
-        const hostspec = getTemplateSrv().replace(query?.hostspec ?? this.hostspec, scopedVars);
         if (isBlank(hostspec)) {
             throw new GenericError(
                 `Please specify a host specification in the datasource settings${orInTheQueryErrorText}.`
             );
         }
 
-        return { url, hostspec };
+        return { url: url!, hostspec: hostspec! };
     }
 
     async metricFindQuery(query: string): Promise<MetricFindValue[]> {
diff --git a/src/datasources/lib/specs/fixtures/grafana.ts b/src/datasources/lib/specs/fixtures/grafana.ts
index 7e72bdd0..46e02a7e 100644
--- a/src/datasources/lib/specs/fixtures/grafana.ts
+++ b/src/datasources/lib/specs/fixtures/grafana.ts
@@ -1,5 +1,7 @@
 import { DataQuery, DataQueryRequest, dateTimeParse, TimeRange } from '@grafana/data';
 import { FetchResponse } from '@grafana/runtime';
+import { defaultsDeep } from 'lodash';
+import { DeepPartial } from 'utility-types';
 
 export function timeRange(): TimeRange {
     return {
@@ -12,8 +14,8 @@ export function timeRange(): TimeRange {
     };
 }
 
-export function dataQueryRequest<Q extends DataQuery>(queries: Q[] = []): DataQueryRequest<Q> {
-    return {
+export function dataQueryRequest<Q extends DataQuery>(props?: DeepPartial<DataQueryRequest<Q>>): DataQueryRequest<Q> {
+    return defaultsDeep({}, props, {
         app: 'dashboard',
         dashboardId: 1,
         panelId: 2,
@@ -24,8 +26,8 @@ export function dataQueryRequest<Q extends DataQuery>(queries: Q[] = []): DataQu
         timezone: '',
         range: timeRange(),
         scopedVars: {},
-        targets: queries,
-    };
+        targets: [],
+    });
 }
 
 export function response<T>(data: T): FetchResponse<T> {
diff --git a/src/datasources/vector/dashboards/pcp-vector-host-overview.jsonnet b/src/datasources/vector/dashboards/pcp-vector-host-overview.jsonnet
index eb5489fa..6208aae3 100644
--- a/src/datasources/vector/dashboards/pcp-vector-host-overview.jsonnet
+++ b/src/datasources/vector/dashboards/pcp-vector-host-overview.jsonnet
@@ -19,6 +19,21 @@ grafana.dashboard.new(
     hide='value',
   )
 )
+.addTemplate(
+  grafana.template.text(
+    'url',
+    label='URL',
+  ) + {
+    description: 'overwrite pmproxy URL (example: http://127.0.0.1:44322)'
+  }
+)
+.addTemplate(
+  grafana.template.text(
+    'hostspec',
+  ) + {
+    description: 'overwrite PCP host specification (example: pcp://127.0.0.1:44321)'
+  }
+)
 
 .addPanel(
   grafana.row.new(
@@ -39,8 +54,8 @@ grafana.dashboard.new(
     stack=true,
   )
   .addTargets([
-    { expr: 'kernel.cpu.util.user', format: 'time_series', legendFormat: '$metric' },
-    { expr: 'kernel.cpu.util.sys', format: 'time_series', legendFormat: '$metric' },
+    { expr: 'kernel.cpu.util.user', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
+    { expr: 'kernel.cpu.util.sys',  format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 1,
@@ -60,7 +75,7 @@ grafana.dashboard.new(
     legend_values=true,
   )
   .addTargets([
-    { expr: 'kernel.all.load', format: 'time_series', legendFormat: '$instance' },
+    { expr: 'kernel.all.load', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 1,
@@ -77,9 +92,9 @@ grafana.dashboard.new(
     stack=true,
   )
   .addTargets([
-    { expr: 'mem.util.free', format: 'time_series', legendFormat: '$metric' },
-    { expr: 'mem.util.cached', format: 'time_series', legendFormat: '$metric' },
-    { expr: 'mem.physmem', format: 'time_series', legendFormat: '$metric' },
+    { expr: 'mem.util.free',   format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
+    { expr: 'mem.util.cached', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
+    { expr: 'mem.physmem',     format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ])
   .addSeriesOverride({
     "alias": "/physmem/",
@@ -101,7 +116,7 @@ grafana.dashboard.new(
     min=0,
   )
   .addTargets([
-    { expr: 'disk.dev.util', format: 'time_series', legendFormat: '$instance' },
+    { expr: 'disk.dev.util', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 8,
@@ -129,7 +144,7 @@ grafana.dashboard.new(
     max=1,
   )
   .addTargets([
-      { expr: 'kernel.percpu.cpu.user', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'kernel.percpu.cpu.user', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 16,
@@ -146,7 +161,7 @@ grafana.dashboard.new(
     max=1,
   )
   .addTargets([
-      { expr: 'kernel.percpu.cpu.sys', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'kernel.percpu.cpu.sys', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 16,
@@ -163,7 +178,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'kernel.cpu.util.user', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'kernel.cpu.util.user', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 23,
@@ -180,7 +195,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'kernel.cpu.util.sys', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'kernel.cpu.util.sys', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 6,
     y: 23,
@@ -197,7 +212,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'kernel.cpu.util.intr', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'kernel.cpu.util.intr', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 23,
@@ -214,7 +229,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'kernel.cpu.util.wait', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'kernel.cpu.util.wait', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 18,
     y: 23,
@@ -242,7 +257,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'kernel.all.pswitch', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'kernel.all.pswitch', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 31,
@@ -260,7 +275,7 @@ grafana.dashboard.new(
     staircase=true,
   )
   .addTargets([
-      { expr: 'kernel.all.runnable', format: 'time_series' , legendFormat: '$metric'},
+      { expr: 'kernel.all.runnable', format: 'time_series' , legendFormat: '$metric', url: '$url', hostspec: '$hostspec'},
   ]), gridPos={
     x: 12,
     y: 31,
@@ -288,7 +303,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'mem.util.used', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'mem.util.used', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 39,
@@ -305,7 +320,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'mem.util.cached', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'mem.util.cached', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 8,
     y: 39,
@@ -322,7 +337,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'mem.util.free', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'mem.util.free', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 16,
     y: 39,
@@ -339,7 +354,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'mem.vmstat.pgfault', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'mem.vmstat.pgfault', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 46,
@@ -356,7 +371,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'mem.vmstat.pgmajfault', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'mem.vmstat.pgmajfault', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 46,
@@ -382,7 +397,7 @@ grafana.dashboard.new(
     format='Bps',
   )
   .addTargets([
-      { expr: 'network.interface.in.bytes', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'network.interface.in.bytes', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 54,
@@ -397,7 +412,7 @@ grafana.dashboard.new(
     format='Bps',
   )
   .addTargets([
-      { expr: 'network.interface.out.bytes', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'network.interface.out.bytes', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 54,
@@ -414,7 +429,7 @@ grafana.dashboard.new(
     decimals=0,
   )
   .addTargets([
-      { expr: 'network.interface.in.drops', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'network.interface.in.drops', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 61,
@@ -431,7 +446,7 @@ grafana.dashboard.new(
     decimals=0,
   )
   .addTargets([
-      { expr: 'network.interface.out.drops', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'network.interface.out.drops', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 61,
@@ -448,7 +463,7 @@ grafana.dashboard.new(
     decimals=0,
   )
   .addTargets([
-      { expr: 'network.interface.in.packets', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'network.interface.in.packets', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 68,
@@ -465,7 +480,7 @@ grafana.dashboard.new(
     decimals=0,
   )
   .addTargets([
-      { expr: 'network.interface.out.packets', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'network.interface.out.packets', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 68,
@@ -493,9 +508,9 @@ grafana.dashboard.new(
     stack=true,
   )
   .addTargets([
-      { expr: 'network.tcpconn.time_wait', format: 'time_series', legendFormat: '$metric' },
-      { expr: 'network.tcpconn.established', format: 'time_series', legendFormat: '$metric' },
-      { expr: 'network.tcpconn.close_wait', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'network.tcpconn.time_wait',   format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
+      { expr: 'network.tcpconn.established', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
+      { expr: 'network.tcpconn.close_wait',  format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 76,
@@ -512,7 +527,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'network.tcp.timeouts', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'network.tcp.timeouts', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 83,
@@ -529,7 +544,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'network.tcpconn.close_wait', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'network.tcpconn.close_wait', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 6,
     y: 83,
@@ -546,7 +561,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'network.tcpconn.time_wait', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'network.tcpconn.time_wait', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 83,
@@ -563,7 +578,7 @@ grafana.dashboard.new(
     legend_show=false,
   )
   .addTargets([
-      { expr: 'network.tcpconn.established', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'network.tcpconn.established', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 18,
     y: 83,
@@ -580,8 +595,8 @@ grafana.dashboard.new(
     decimals=0,
   )
   .addTargets([
-      { expr: 'network.tcp.listendrops', format: 'time_series', legendFormat: '$metric' },
-      { expr: 'network.tcp.listenoverflows', format: 'time_series', legendFormat: '$metric' },
+      { expr: 'network.tcp.listendrops',     format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
+      { expr: 'network.tcp.listenoverflows', format: 'time_series', legendFormat: '$metric', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 90,
@@ -598,10 +613,10 @@ grafana.dashboard.new(
     decimals=0,
   )
   .addTargets([
-      { expr: 'network.tcp.retranssegs', format: 'time_series', legendFormat: '$metric0' },
-      { expr: 'network.tcp.fastretrans', format: 'time_series', legendFormat: '$metric0' },
-      { expr: 'network.tcp.slowstartretrans', format: 'time_series', legendFormat: '$metric0' },
-      { expr: 'network.tcp.synretrans', format: 'time_series', legendFormat: '$metric0' },
+      { expr: 'network.tcp.retranssegs',      format: 'time_series', legendFormat: '$metric0', url: '$url', hostspec: '$hostspec' },
+      { expr: 'network.tcp.fastretrans',      format: 'time_series', legendFormat: '$metric0', url: '$url', hostspec: '$hostspec' },
+      { expr: 'network.tcp.slowstartretrans', format: 'time_series', legendFormat: '$metric0', url: '$url', hostspec: '$hostspec' },
+      { expr: 'network.tcp.synretrans',       format: 'time_series', legendFormat: '$metric0', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 90,
@@ -628,8 +643,8 @@ grafana.dashboard.new(
     min=0,
   )
   .addTargets([
-      { expr: 'disk.dev.read_rawactive', legendFormat: 'read $instance', format: 'time_series' },
-      { expr: 'disk.dev.write_rawactive', legendFormat: 'write $instance', format: 'time_series' },
+      { expr: 'disk.dev.read_rawactive',  format: 'time_series', legendFormat: 'read $instance',  url: '$url', hostspec: '$hostspec' },
+      { expr: 'disk.dev.write_rawactive', format: 'time_series', legendFormat: 'write $instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 98,
@@ -645,8 +660,8 @@ grafana.dashboard.new(
     min=0,
   )
   .addTargets([
-      { expr: 'disk.dev.read', legendFormat: 'read $instance', format: 'time_series' },
-      { expr: 'disk.dev.write', legendFormat: 'write $instance', format: 'time_series' },
+      { expr: 'disk.dev.read',  format: 'time_series',  legendFormat: 'read $instance',  url: '$url', hostspec: '$hostspec' },
+      { expr: 'disk.dev.write', format: 'time_series',  legendFormat: 'write $instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 98,
@@ -662,8 +677,8 @@ grafana.dashboard.new(
     min=0,
   )
   .addTargets([
-      { expr: 'disk.dev.read_bytes', legendFormat: 'read $instance', format: 'time_series' },
-      { expr: 'disk.dev.write_bytes', legendFormat: 'write $instance', format: 'time_series' },
+      { expr: 'disk.dev.read_bytes',  format: 'time_series',  legendFormat: 'read $instance',  url: '$url', hostspec: '$hostspec' },
+      { expr: 'disk.dev.write_bytes', format: 'time_series',  legendFormat: 'write $instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 0,
     y: 105,
@@ -680,7 +695,7 @@ grafana.dashboard.new(
     max=1,
   )
   .addTargets([
-      { expr: 'disk.dev.avactive', format: 'time_series', legendFormat: '$instance' },
+      { expr: 'disk.dev.avactive', format: 'time_series', legendFormat: '$instance', url: '$url', hostspec: '$hostspec' },
   ]), gridPos={
     x: 12,
     y: 105,
diff --git a/src/datasources/vector/datasource.test.ts b/src/datasources/vector/datasource.test.ts
index 8e816971..58e9ca89 100644
--- a/src/datasources/vector/datasource.test.ts
+++ b/src/datasources/vector/datasource.test.ts
@@ -12,7 +12,7 @@ jest.mock('@grafana/runtime', () => ({
     ...jest.requireActual<object>('@grafana/runtime'),
     getBackendSrv: () => backendSrvMock,
     getTemplateSrv: () => ({
-        replace: (x: string) => x,
+        replace: (x: string) => x.replace('$empty_dashboard_var', ''),
     }),
 }));
 
@@ -33,8 +33,8 @@ describe('PCP Vector', () => {
     });
 
     it('should poll disk.dev.read, perform rate conversion and return the result', async () => {
-        const queries = [ds.query()];
-        let response = await datasource.query(grafana.dataQueryRequest(queries));
+        const targets = [ds.query()];
+        let response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toEqual({ data: [] });
 
         mockNextResponses([
@@ -57,7 +57,7 @@ describe('PCP Vector', () => {
         ]);
         await datasource.poller.poll();
 
-        response = await datasource.query(grafana.dataQueryRequest(queries));
+        response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect({ fields: response.data[0].fields }).toMatchInlineSnapshot(
             {
                 fields: [{}, { config: { custom: expect.anything() } }, { config: { custom: expect.anything() } }],
@@ -123,7 +123,7 @@ describe('PCP Vector', () => {
             Array [
               Object {
                 "params": Object {
-                  "hostspec": "127.0.0.1",
+                  "hostspec": "pcp://127.0.0.1",
                   "polltimeout": 11,
                 },
                 "url": "http://localhost:1234/pmapi/context",
@@ -267,8 +267,8 @@ describe('PCP Vector', () => {
     });
 
     it.skip('redisBackfill hook should use panel url', async () => {
-        const queries = [ds.query({ expr: 'kernel.all.sysfork', url: 'http://panel_url:1234' })];
-        let response = await datasource.query(grafana.dataQueryRequest(queries));
+        const targets = [ds.query({ expr: 'kernel.all.sysfork', url: 'http://panel_url:1234' })];
+        let response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toEqual({ data: [] });
 
         mockNextResponses([
@@ -281,7 +281,7 @@ describe('PCP Vector', () => {
         ]);
         await datasource.poller.poll();
 
-        response = await datasource.query(grafana.dataQueryRequest(queries));
+        response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect({ fields: response.data[0].fields }).toMatchInlineSnapshot(
             { fields: [{}, { config: { custom: expect.anything() } }] },
 
@@ -325,7 +325,7 @@ describe('PCP Vector', () => {
             Array [
               Object {
                 "params": Object {
-                  "hostspec": "127.0.0.1",
+                  "hostspec": "pcp://127.0.0.1",
                   "polltimeout": 11,
                 },
                 "url": "http://panel_url:1234/pmapi/context",
@@ -380,7 +380,7 @@ describe('PCP Vector: overridden url and hostspec', () => {
         const datasource = new PCPVectorDataSource(instanceSettings as any);
         const targets = [{ refId: 'A', expr: 'mem.util.free', format: TargetFormat.TimeSeries }];
 
-        let response = await datasource.query(grafana.dataQueryRequest(targets));
+        let response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toEqual({ data: [] });
 
         mockNextResponses([
@@ -391,7 +391,7 @@ describe('PCP Vector: overridden url and hostspec', () => {
         ]);
         await datasource.poller.poll();
 
-        response = await datasource.query(grafana.dataQueryRequest(targets));
+        response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toMatchObject({
             data: [{ fields: [{ values: { buffer: [10000] } }, { values: { buffer: [1000] } }] }],
         });
@@ -434,7 +434,7 @@ describe('PCP Vector: overridden url and hostspec', () => {
             { refId: 'A', expr: 'mem.util.free', format: TargetFormat.TimeSeries, url: 'http://panel_host:8080' },
         ];
 
-        let response = await datasource.query(grafana.dataQueryRequest(targets));
+        let response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toEqual({ data: [] });
 
         mockNextResponses([
@@ -445,7 +445,7 @@ describe('PCP Vector: overridden url and hostspec', () => {
         ]);
         await datasource.poller.poll();
 
-        response = await datasource.query(grafana.dataQueryRequest(targets));
+        response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toMatchObject({
             data: [{ fields: [{ values: { buffer: [10000] } }, { values: { buffer: [1000] } }] }],
         });
@@ -493,7 +493,7 @@ describe('PCP Vector: overridden url and hostspec', () => {
             },
         ];
 
-        let response = await datasource.query(grafana.dataQueryRequest(targets));
+        let response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toEqual({ data: [] });
 
         mockNextResponses([
@@ -504,7 +504,7 @@ describe('PCP Vector: overridden url and hostspec', () => {
         ]);
         await datasource.poller.poll();
 
-        response = await datasource.query(grafana.dataQueryRequest(targets));
+        response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toMatchObject({
             data: [{ fields: [{ values: { buffer: [10000] } }, { values: { buffer: [1000] } }] }],
         });
@@ -553,7 +553,7 @@ describe('PCP Vector: overridden url and hostspec', () => {
             },
         ];
 
-        let response = await datasource.query(grafana.dataQueryRequest(targets));
+        let response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toEqual({ data: [] });
 
         mockNextResponses([
@@ -564,7 +564,7 @@ describe('PCP Vector: overridden url and hostspec', () => {
         ]);
         await datasource.poller.poll();
 
-        response = await datasource.query(grafana.dataQueryRequest(targets));
+        response = await datasource.query(grafana.dataQueryRequest({ targets }));
         expect(response).toMatchObject({
             data: [{ fields: [{ values: { buffer: [10000] } }, { values: { buffer: [1000] } }] }],
         });
@@ -594,4 +594,63 @@ describe('PCP Vector: overridden url and hostspec', () => {
             ]
         `);
     });
+
+    it('should use datasource url if overwritten url is blank', async () => {
+        const instanceSettings = {
+            url: 'http://settings_host:1234',
+            jsonData: {
+                hostspec: 'pcp://settings_hostspec:4321',
+            },
+        };
+        const datasource = new PCPVectorDataSource(instanceSettings as any);
+        const targets = [
+            {
+                refId: 'A',
+                expr: 'mem.util.free',
+                format: TargetFormat.TimeSeries,
+                url: '$empty_dashboard_var',
+            },
+        ];
+
+        let response = await datasource.query(grafana.dataQueryRequest({ targets }));
+        expect(response).toEqual({ data: [] });
+
+        mockNextResponses([
+            pmapi.context(),
+            //pmseries.ping(false),
+            pmapi.metric(['mem.util.free']),
+            pmapi.fetch('mem.util.free', 10, [[null, 1000]]),
+        ]);
+        await datasource.poller.poll();
+
+        response = await datasource.query(grafana.dataQueryRequest({ targets }));
+        expect(response).toMatchObject({
+            data: [{ fields: [{ values: { buffer: [10000] } }, { values: { buffer: [1000] } }] }],
+        });
+        expect(backendSrvMock.fetch.mock.calls.map(([{ url, params }]) => ({ url, params }))).toMatchInlineSnapshot(`
+            Array [
+              Object {
+                "params": Object {
+                  "hostspec": "pcp://settings_hostspec:4321",
+                  "polltimeout": 11,
+                },
+                "url": "http://settings_host:1234/pmapi/context",
+              },
+              Object {
+                "params": Object {
+                  "context": 123,
+                  "names": "mem.util.free",
+                },
+                "url": "http://settings_host:1234/pmapi/metric",
+              },
+              Object {
+                "params": Object {
+                  "context": 123,
+                  "names": "mem.util.free",
+                },
+                "url": "http://settings_host:1234/pmapi/fetch",
+              },
+            ]
+        `);
+    });
 });