Hello Team,

I believe I was able to reproduce this issue in my env.
- I added 9 NetApp Share Backends to Manila(Backend details shown in the Session 5th output).
- I am trying to create manila shares continuously in 3 different sessions.
- In an another parallel session I am grepping the logs to see if any Backend is reported as down because of the above bug. -- 4th session
- In an another session I am running "manila service-list | grep ontap | grep down" continuously. -- 5th session

Note : The services were not restarted during this time frame. 
       The services were restarted at least 20 mins before running this activity.

I have captured the data for a 10 second timeframe (Fri Apr 12 06:20:39 EDT 2019) to Fri Apr 12 06:20:48 EDT 2019.
Here is the session output from the 5th session.

################################# Session 5 output #################################
root@25-nareshtwo:/home/stack# date
Fri Apr 12 06:20:39 EDT 2019
root@25-nareshtwo:/home/stack# manila service-list
+----+------------------+----------------------------+---------------+---------+-------+----------------------------+
| Id | Binary           | Host                       | Zone          | Status  | State | Updated_at                 |
+----+------------------+----------------------------+---------------+---------+-------+----------------------------+
| 1  | manila-share     | 25-nareshtwo@london        | manila-zone-0 | enabled | down  | 2019-04-12T09:58:12.000000 |
| 2  | manila-share     | 25-nareshtwo@paris         | manila-zone-1 | enabled | down  | 2019-04-12T09:58:12.000000 |
| 3  | manila-scheduler | 25-nareshtwo               | nova          | enabled | up    | 2019-04-12T10:20:36.000000 |
| 4  | manila-data      | 25-nareshtwo               | nova          | enabled | up    | 2019-04-12T10:20:43.000000 |
| 5  | manila-share     | 25-nareshtwo@ontap2        | nova          | enabled | up    | 2019-04-12T10:20:41.000000 |
| 6  | manila-share     | 25-nareshtwo@ontap6        | nova          | enabled | up    | 2019-04-12T10:20:41.000000 |
| 7  | manila-share     | 25-nareshtwo@ontapreplica6 | nova          | enabled | up    | 2019-04-12T10:20:41.000000 |
| 8  | manila-share     | 25-nareshtwo@ontapreplica2 | nova          | enabled | up    | 2019-04-12T10:20:41.000000 |
| 9  | manila-share     | 25-nareshtwo@ontap33       | nova          | enabled | up    | 2019-04-12T10:20:41.000000 |
| 10 | manila-share     | 25-nareshtwo@ontap3        | nova          | enabled | up    | 2019-04-12T10:20:42.000000 |
| 11 | manila-share     | 25-nareshtwo@ontapreplica3 | nova          | enabled | up    | 2019-04-12T10:20:42.000000 |
| 12 | manila-share     | 25-nareshtwo@ontap4        | nova          | enabled | up    | 2019-04-12T10:20:41.000000 |
| 13 | manila-share     | 25-nareshtwo@ontapreplica4 | nova          | enabled | up    | 2019-04-12T10:20:41.000000 |
+----+------------------+----------------------------+---------------+---------+-------+----------------------------+
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# manila service-list | grep ontap | grep down
root@25-nareshtwo:/home/stack# date
Fri Apr 12 06:20:48 EDT 2019
################################# Session 5 output #################################


Here is the o/p from the session 4.
################################# Session 4 output #################################
root@25-nareshtwo:/home/stack# sudo journalctl -f --unit devstack@m-* | grep "Share service is down"
Apr 12 06:20:38 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-51824e55-b562-4ca0-a678-66a97a850e77 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
Apr 12 06:20:38 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-51824e55-b562-4ca0-a678-66a97a850e77 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@paris).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a5b621b0-506f-47d8-b2fc-fe63d98c37c0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica2).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a5b621b0-506f-47d8-b2fc-fe63d98c37c0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap33).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a5b621b0-506f-47d8-b2fc-fe63d98c37c0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap3).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a5b621b0-506f-47d8-b2fc-fe63d98c37c0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica3).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a5b621b0-506f-47d8-b2fc-fe63d98c37c0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap4).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a5b621b0-506f-47d8-b2fc-fe63d98c37c0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-2ead931c-8825-4328-8802-dd07fd753e96 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica2).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-2ead931c-8825-4328-8802-dd07fd753e96 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap33).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-2ead931c-8825-4328-8802-dd07fd753e96 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap3).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-2ead931c-8825-4328-8802-dd07fd753e96 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica3).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-2ead931c-8825-4328-8802-dd07fd753e96 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap4).#033[00m#033[00m
Apr 12 06:20:40 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-2ead931c-8825-4328-8802-dd07fd753e96 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:41 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-3fd196a0-f7eb-46be-b560-c52cb2b69bb4 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:42 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a736bbb3-04b2-4a45-8345-72a91dbf2ac0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica6).#033[00m#033[00m
Apr 12 06:20:42 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a736bbb3-04b2-4a45-8345-72a91dbf2ac0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica2).#033[00m#033[00m
Apr 12 06:20:42 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a736bbb3-04b2-4a45-8345-72a91dbf2ac0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap33).#033[00m#033[00m
Apr 12 06:20:42 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a736bbb3-04b2-4a45-8345-72a91dbf2ac0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap3).#033[00m#033[00m
Apr 12 06:20:42 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a736bbb3-04b2-4a45-8345-72a91dbf2ac0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica3).#033[00m#033[00m
Apr 12 06:20:42 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a736bbb3-04b2-4a45-8345-72a91dbf2ac0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontap4).#033[00m#033[00m
Apr 12 06:20:42 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-a736bbb3-04b2-4a45-8345-72a91dbf2ac0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:43 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-486fdf2f-3655-4601-aa3e-12cf86039655 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:43 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-0423726b-56be-4fcd-b193-7dc9f9f33bb0 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:47 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-b6fdd2ff-25d6-4c5d-85eb-8172b79eeede #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:49 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-4ed87b98-1ed8-4d92-8465-92e61bbfc0e1 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:49 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-677519f6-c1e0-4ca0-93dd-bfc1fdffd508 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:49 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-92e68701-2072-46ab-a431-7dfbf17c46a4 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
Apr 12 06:20:49 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-92e68701-2072-46ab-a431-7dfbf17c46a4 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@paris).#033[00m#033[00m
Apr 12 06:20:49 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-15528cab-49d9-433a-8866-31a663c7c0c3 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
Apr 12 06:20:49 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-15528cab-49d9-433a-8866-31a663c7c0c3 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@paris).#033[00m#033[00m
Apr 12 06:20:49 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-56b9ad3a-d563-4fa7-8a16-0d9ea1960b96 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
Apr 12 06:20:49 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-56b9ad3a-d563-4fa7-8a16-0d9ea1960b96 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@paris).#033[00m#033[00m
Apr 12 06:20:50 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-fc567199-a9e1-48ec-87df-1a1af066061b #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
Apr 12 06:20:50 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-fc567199-a9e1-48ec-87df-1a1af066061b #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@paris).#033[00m#033[00m
Apr 12 06:20:50 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-c55ae71f-1b95-4d17-b4dc-ef58a938696c #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
Apr 12 06:20:50 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-c55ae71f-1b95-4d17-b4dc-ef58a938696c #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@paris).#033[00m#033[00m
Apr 12 06:20:51 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-6aa61b15-c12c-40b6-bc6a-03c31ac78b17 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
Apr 12 06:20:51 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-6aa61b15-c12c-40b6-bc6a-03c31ac78b17 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@paris).#033[00m#033[00m
Apr 12 06:20:51 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-7a8227da-0d97-4bf9-bc0f-ab2f4904e5bb #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
Apr 12 06:20:51 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-7a8227da-0d97-4bf9-bc0f-ab2f4904e5bb #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@paris).#033[00m#033[00m
Apr 12 06:20:52 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-59dfcdfa-b024-462a-b89e-41ff699af13f #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@ontapreplica4).#033[00m#033[00m
Apr 12 06:20:52 ubuntu manila-scheduler[13685]: #033[01;33mWARNING manila.scheduler.host_manager [#033[01;36mNone req-3b954699-2e9c-4447-8608-ce5a141dbcc4 #033[00;36mNone None#033[01;33m] #033[01;35m#033[01;33mShare service is down. (host: 25-nareshtwo@london).#033[00m#033[00m
################################# Session 4 output ################################# 

From the above tests we can see that Backend Service is reported to be down only in the manila scheduler logs(Session 5) but not in the "manila service-list" command(Session 4).
If you guys are aware of this issue can you please confirm this behavior?

Thanks,
Naresh