Can not mongo from 3.6 to version v4.2 on Splunk 8.1

[ribentrop]

Hello, Splunkers!

I'v just change storageEngine to wiredTiger on my single instance.

[root@splunk-1 opt]# /opt/splunk/bin/splunk version
Splunk 8.1.10.1 (build 8bfab9b850ca)
[root@splunk-1 opt]# /opt/splunk/bin/splunk show kvstore-status --verbose

 This member:
                           backupRestoreStatus : Ready
                                          date : Wed Apr 23 09:56:56 2025
                                       dateSec : 1745391416.331
                                      disabled : 0
                                          guid : 3FA11F27-42E0-400A-BF69-D15F6B534708
                             oplogEndTimestamp : Wed Apr 23 09:56:55 2025
                          oplogEndTimestampSec : 1745391415
                           oplogStartTimestamp : Wed Apr 23 09:50:13 2025
                        oplogStartTimestampSec : 1745391013
                                          port : 8191
                                    replicaSet : 3FA11F27-42E0-400A-BF69-D15F6B534708
                             replicationStatus : KV store captain
                                    standalone : 1
                                        status : ready
                                 storageEngine : wiredTiger

 KV store members:
        127.0.0.1:8191
                                 configVersion : 1
                                  electionDate : Wed Apr 23 09:55:23 2025
                               electionDateSec : 1745391323
                                   hostAndPort : 127.0.0.1:8191
                                    optimeDate : Wed Apr 23 09:56:55 2025
                                 optimeDateSec : 1745391415
                             replicationStatus : KV store captain
                                        uptime : 95

Now I'm trying to upgrade mongo version from 3.6 to version v4.2. According to mongod.log my current version is:

 2025-04-23T06:55:21.374Z I CONTROL  [initandlisten] db version v3.6.17-linux-splunk-v4

Now according to docs I'm trying to migrate to another version of mongo manually but get the following message:

[root@splunk-1 opt]# /opt/splunk/bin/splunk migrate migrate-kvstore
[App Key Value Store migration] Collection data is not available.

Whst Splunk means by that? "Collection data is not available". I have several collections in my Splunk. I haven't found any case in Community. In normal cases Splunk replies in something like "Collection data is not available" .

It seems that I do something wrong in genelal

Thanks

[livehybrid]

Hi @ribentrop 

Based on your kvstore status output it looks like the upgrade has already been completed. I think you would see that message if there no collections to be converted to wiredTiger.

• Are there subdirectories and files in $SPLUNK_HOME/var/lib/splunk/kvstore/mongo?
• Look for .wt files (WiredTiger), or collection*, index* files (old mmapv1).

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[ribentrop]

Hi @livehybrid !

Thank for yuou response.

---

• Are there subdirectories and files in $SPLUNK_HOME/var/lib/splunk/kvstore/mongo?
• Look for .wt files (WiredTiger), or collection*, index* files (old mmapv1).

---

Actually they are:

[root@splunk-1 splunk]# ll /opt/splunk/var/lib/splunk/kvstore/mongo | grep wt | wc -l
54

 But my question is actually about mongo version. Here it is on Splunk 8.1

[root@splunk-1 splunk]# /opt/splunk/bin/splunk cmd mongod --version
db version v3.6.17-linux-splunk-v4

So I want it to upgrade to 4.2 via command /opt/splunk/bin/splunk migrate /opt/splunk/bin/splunk migrate but still no luck and no any error info.

[ribentrop]

Missprint here:

In normal cases Splunk replies in something like "[App Key Value Store migration] Starting migrate-kvstore." .