diff --git a/services/web/app/src/Features/Compile/ClsiCookieManager.js b/services/web/app/src/Features/Compile/ClsiCookieManager.js
index f84526eaea..f7909ad1e5 100644
--- a/services/web/app/src/Features/Compile/ClsiCookieManager.js
+++ b/services/web/app/src/Features/Compile/ClsiCookieManager.js
@@ -39,7 +39,13 @@ module.exports = function (backendGroup) {
       }
     },
 
-    _getServerId(project_id, user_id, compileGroup, callback) {
+    _getServerId(
+      project_id,
+      user_id,
+      compileGroup,
+      compileBackendClass,
+      callback
+    ) {
       if (callback == null) {
         callback = function () {}
       }
@@ -54,6 +60,7 @@ module.exports = function (backendGroup) {
               project_id,
               user_id,
               compileGroup,
+              compileBackendClass,
               callback
             )
           } else {
@@ -63,14 +70,23 @@ module.exports = function (backendGroup) {
       )
     },
 
-    _populateServerIdViaRequest(project_id, user_id, compileGroup, callback) {
+    _populateServerIdViaRequest(
+      project_id,
+      user_id,
+      compileGroup,
+      compileBackendClass,
+      callback
+    ) {
       if (callback == null) {
         callback = function () {}
       }
       const u = new URL(
         `${Settings.apis.clsi.url}/project/${project_id}/status`
       )
-      u.search = new URLSearchParams({ compileGroup }).toString()
+      u.search = new URLSearchParams({
+        compileGroup,
+        compileBackendClass,
+      }).toString()
       request.post(u.href, (err, res, body) => {
         if (err != null) {
           OError.tag(err, 'error getting initial server id for project', {
@@ -82,6 +98,7 @@ module.exports = function (backendGroup) {
           project_id,
           user_id,
           compileGroup,
+          compileBackendClass,
           res,
           null,
           function (err, serverId) {
@@ -106,11 +123,11 @@ module.exports = function (backendGroup) {
       return cookies != null ? cookies[Settings.clsiCookie.key] : undefined
     },
 
-    checkIsLoadSheddingEvent(clsiserverid, compileGroup) {
+    checkIsLoadSheddingEvent(clsiserverid, compileGroup, compileBackendClass) {
       request.get(
         {
           url: `${Settings.apis.clsi.url}/instance-state`,
-          qs: { clsiserverid, compileGroup },
+          qs: { clsiserverid, compileGroup, compileBackendClass },
         },
         (err, res, body) => {
           if (err) {
@@ -139,6 +156,7 @@ module.exports = function (backendGroup) {
       project_id,
       user_id,
       compileGroup,
+      compileBackendClass,
       response,
       previous,
       callback
@@ -162,7 +180,11 @@ module.exports = function (backendGroup) {
         // Initial assignment of a user+project or after clearing cache.
         Metrics.inc('clsi-lb-assign-initial-backend')
       } else {
-        this.checkIsLoadSheddingEvent(previous, compileGroup)
+        this.checkIsLoadSheddingEvent(
+          previous,
+          compileGroup,
+          compileBackendClass
+        )
       }
       if (rclient_secondary != null) {
         this._setServerIdInRedis(
@@ -200,7 +222,13 @@ module.exports = function (backendGroup) {
       return rclient.del(this.buildKey(project_id, user_id), callback)
     },
 
-    getCookieJar(project_id, user_id, compileGroup, callback) {
+    getCookieJar(
+      project_id,
+      user_id,
+      compileGroup,
+      compileBackendClass,
+      callback
+    ) {
       if (callback == null) {
         callback = function () {}
       }
@@ -211,6 +239,7 @@ module.exports = function (backendGroup) {
         project_id,
         user_id,
         compileGroup,
+        compileBackendClass,
         (err, serverId) => {
           if (err != null) {
             OError.tag(err, 'error getting server id', {
diff --git a/services/web/app/src/Features/Compile/ClsiManager.js b/services/web/app/src/Features/Compile/ClsiManager.js
index 549e809ae4..bf3824cf93 100644
--- a/services/web/app/src/Features/Compile/ClsiManager.js
+++ b/services/web/app/src/Features/Compile/ClsiManager.js
@@ -134,7 +134,14 @@ const ClsiManager = {
       url: compilerUrl,
       method: 'POST',
     }
-    ClsiManager._makeRequest(projectId, userId, compileGroup, opts, callback)
+    ClsiManager._makeRequest(
+      projectId,
+      userId,
+      compileGroup,
+      compileBackendClass,
+      opts,
+      callback
+    )
   },
 
   deleteAuxFiles(projectId, userId, options, clsiserverid, callback) {
@@ -156,6 +163,7 @@ const ClsiManager = {
       projectId,
       userId,
       compileGroup,
+      compileBackendClass,
       opts,
       clsiserverid,
       clsiErr => {
@@ -283,13 +291,17 @@ const ClsiManager = {
     projectId,
     userId,
     compileGroup,
+    compileBackendClass,
     opts,
     clsiserverid,
     callback
   ) {
     if (clsiserverid) {
       // ignore cookies and newBackend, go straight to the clsi node
-      opts.qs = Object.assign({ compileGroup, clsiserverid }, opts.qs)
+      opts.qs = Object.assign(
+        { compileGroup, compileBackendClass, clsiserverid },
+        opts.qs
+      )
       request(opts, (err, response, body) => {
         if (err) {
           return callback(
@@ -299,11 +311,25 @@ const ClsiManager = {
         callback(null, response, body)
       })
     } else {
-      ClsiManager._makeRequest(projectId, userId, compileGroup, opts, callback)
+      ClsiManager._makeRequest(
+        projectId,
+        userId,
+        compileGroup,
+        compileBackendClass,
+        opts,
+        callback
+      )
     }
   },
 
-  _makeRequest(projectId, userId, compileGroup, opts, callback) {
+  _makeRequest(
+    projectId,
+    userId,
+    compileGroup,
+    compileBackendClass,
+    opts,
+    callback
+  ) {
     async.series(
       {
         currentBackend(cb) {
@@ -312,6 +338,7 @@ const ClsiManager = {
             projectId,
             userId,
             compileGroup,
+            compileBackendClass,
             (err, jar, clsiServerId) => {
               if (err != null) {
                 return callback(
@@ -338,6 +365,7 @@ const ClsiManager = {
                   projectId,
                   userId,
                   compileGroup,
+                  compileBackendClass,
                   response,
                   clsiServerId,
                   (err, newClsiServerId) => {
@@ -373,6 +401,7 @@ const ClsiManager = {
             projectId,
             userId,
             compileGroup,
+            compileBackendClass,
             opts,
             (err, response, body) => {
               if (err != null) {
@@ -419,7 +448,14 @@ const ClsiManager = {
     )
   },
 
-  _makeNewBackendRequest(projectId, userId, compileGroup, baseOpts, callback) {
+  _makeNewBackendRequest(
+    projectId,
+    userId,
+    compileGroup,
+    compileBackendClass,
+    baseOpts,
+    callback
+  ) {
     if (Settings.apis.clsi_new == null || Settings.apis.clsi_new.url == null) {
       return callback()
     }
@@ -434,6 +470,7 @@ const ClsiManager = {
       projectId,
       userId,
       compileGroup,
+      compileBackendClass,
       (err, jar, clsiServerId) => {
         if (err != null) {
           return callback(
@@ -458,6 +495,7 @@ const ClsiManager = {
             projectId,
             userId,
             compileGroup,
+            compileBackendClass,
             response,
             clsiServerId,
             err => {
@@ -521,6 +559,7 @@ const ClsiManager = {
       projectId,
       userId,
       compileGroup,
+      compileBackendClass,
       opts,
       (err, response, body, clsiServerId) => {
         if (err != null) {
@@ -938,6 +977,7 @@ const ClsiManager = {
         projectId,
         userId,
         compileGroup,
+        compileBackendClass,
         opts,
         clsiserverid,
         (err, response, body) => {
diff --git a/services/web/app/src/Features/Compile/CompileController.js b/services/web/app/src/Features/Compile/CompileController.js
index 82518097ac..5503a94741 100644
--- a/services/web/app/src/Features/Compile/CompileController.js
+++ b/services/web/app/src/Features/Compile/CompileController.js
@@ -644,6 +644,7 @@ function _getPersistenceOptions(
       projectId,
       userId,
       compileGroup,
+      compileBackendClass,
       (err, jar) => {
         callback(err, { jar, qs: { compileGroup, compileBackendClass } })
       }
diff --git a/services/web/test/unit/src/Compile/ClsiCookieManagerTests.js b/services/web/test/unit/src/Compile/ClsiCookieManagerTests.js
index 56705e3252..76f5fcf486 100644
--- a/services/web/test/unit/src/Compile/ClsiCookieManagerTests.js
+++ b/services/web/test/unit/src/Compile/ClsiCookieManagerTests.js
@@ -69,6 +69,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         '',
+        'e2',
         (err, serverId) => {
           this.redis.get
             .calledWith(`clsiserver:${this.project_id}:${this.user_id}`)
@@ -106,6 +107,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         '',
+        'e2',
         (err, serverId) => {
           this.ClsiCookieManager._populateServerIdViaRequest
             .calledWith(this.project_id, this.user_id)
@@ -130,12 +132,14 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         (err, serverId) => {
           const args = this.ClsiCookieManager.setServerId.args[0]
           args[0].should.equal(this.project_id)
           args[1].should.equal(this.user_id)
           args[2].should.equal('standard')
-          args[3].should.deep.equal(this.response)
+          args[3].should.equal('e2')
+          args[4].should.deep.equal(this.response)
           return done()
         }
       )
@@ -146,6 +150,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         '',
+        'e2',
         (err, serverId) => {
           serverId.should.equal('clsi-9')
           return done()
@@ -167,6 +172,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.response,
         null,
         err => {
@@ -190,6 +196,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.response,
         null,
         err => {
@@ -208,6 +215,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.response,
         null,
         (err, serverId) => {
@@ -229,6 +237,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.response,
         null,
         (err, serverId) => {
@@ -246,6 +255,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.response,
         null,
         (err, serverId) => {
@@ -276,6 +286,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.response,
         null,
         (err, serverId) => {
@@ -304,6 +315,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         '',
+        'e2',
         (err, jar) => {
           jar._jar.store.idx['clsi.example.com']['/'][
             this.settings.clsiCookie.key
@@ -328,6 +340,7 @@ describe('ClsiCookieManager', function () {
         this.project_id,
         this.user_id,
         '',
+        'e2',
         (err, jar) => {
           assert.deepEqual(jar, realRequst.jar())
           return done()
diff --git a/services/web/test/unit/src/Compile/ClsiManagerTests.js b/services/web/test/unit/src/Compile/ClsiManagerTests.js
index 078a049959..2042de8b13 100644
--- a/services/web/test/unit/src/Compile/ClsiManagerTests.js
+++ b/services/web/test/unit/src/Compile/ClsiManagerTests.js
@@ -514,6 +514,7 @@ describe('ClsiManager', function () {
             this.project_id,
             this.user_id,
             'standard',
+            'e2',
             {
               method: 'DELETE',
               url: `${this.settings.apis.clsi.url}/project/${this.project_id}/user/${this.user_id}?compileBackendClass=e2&compileGroup=standard`,
@@ -965,7 +966,7 @@ describe('ClsiManager', function () {
       it('should send the request to the CLSI', function () {
         const url = `${this.settings.apis.clsi.url}/project/${this.project_id}/user/${this.user_id}/compile?compileBackendClass=e2&compileGroup=standard`
         this.ClsiManager._makeRequest
-          .calledWith(this.project_id, this.user_id, 'standard', {
+          .calledWith(this.project_id, this.user_id, 'standard', 'e2', {
             method: 'POST',
             url,
             json: this.req,
@@ -1030,6 +1031,7 @@ describe('ClsiManager', function () {
             this.project_id,
             this.user_id,
             'standard',
+            'e2',
             {
               method: 'GET',
               url: `http://clsi.example.com/project/${this.project_id}/user/${this.user_id}/wordcount?compileBackendClass=e2&compileGroup=standard`,
@@ -1067,6 +1069,7 @@ describe('ClsiManager', function () {
             this.project_id,
             this.user_id,
             'standard',
+            'e2',
             {
               method: 'GET',
               url: `http://clsi.example.com/project/${this.project_id}/user/${this.user_id}/wordcount?compileBackendClass=e2&compileGroup=standard`,
@@ -1099,6 +1102,7 @@ describe('ClsiManager', function () {
             this.project_id,
             this.user_id,
             'standard',
+            'e2',
             {
               method: 'GET',
               url: `http://clsi.example.com/project/${this.project_id}/user/${this.user_id}/wordcount?compileBackendClass=e2&compileGroup=standard`,
@@ -1127,6 +1131,7 @@ describe('ClsiManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.opts,
         () => {
           const args = this.request.args[0]
@@ -1143,6 +1148,7 @@ describe('ClsiManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.opts,
         () => {
           this.ClsiCookieManager.setServerId
@@ -1150,6 +1156,7 @@ describe('ClsiManager', function () {
               this.project_id,
               this.user_id,
               'standard',
+              'e2',
               this.response
             )
             .should.equal(true)
@@ -1175,6 +1182,7 @@ describe('ClsiManager', function () {
           this.project_id,
           this.user_id,
           'standard',
+          'e2',
           this.opts,
           undefined,
           err => {
@@ -1194,6 +1202,7 @@ describe('ClsiManager', function () {
           this.project_id,
           this.user_id,
           'standard',
+          'e2',
           this.opts,
           undefined,
           err => {
@@ -1203,6 +1212,7 @@ describe('ClsiManager', function () {
                 this.project_id,
                 this.user_id,
                 'standard',
+                'e2',
                 this.response
               )
               .should.equal(true)
@@ -1218,6 +1228,7 @@ describe('ClsiManager', function () {
           this.project_id,
           this.user_id,
           'standard',
+          'e2',
           this.opts,
           'node-1',
           err => {
@@ -1229,6 +1240,7 @@ describe('ClsiManager', function () {
             expect(requestOpts.qs).to.deep.equal({
               clsiserverid: 'node-1',
               compileGroup: 'standard',
+              compileBackendClass: 'e2',
             })
             done()
           }
@@ -1240,6 +1252,7 @@ describe('ClsiManager', function () {
           this.project_id,
           this.user_id,
           'standard',
+          'e2',
           this.opts,
           'node-1',
           err => {
@@ -1271,6 +1284,7 @@ describe('ClsiManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.opts,
         () => {
           const args = this.request.args[0]
@@ -1288,6 +1302,7 @@ describe('ClsiManager', function () {
         this.project_id,
         this.user_id,
         'standard',
+        'e2',
         this.opts,
         err => {
           expect(err).to.equal(undefined)