High Availability and Distributed Systems

The recommended approach for sharing directories between servers is:

1. Set up a central network attached storage server.
2. Create a directory structure on the storage server that mirrors the directories listed in the table above.
3. Replace the above directories on each server with links to the corresponding directory on the network attached storage server.

I have setup a NAS storage and granted READ write for the nodes in the load balance setup.

Do you know how to properly implement step 3. above? are you mapping each folder directly or using a symbolic link?

Share the following directories across all servers:

• APPIAN_HOME/_admin/accdocs1/
• APPIAN_HOME/_admin/accdocs2/
• APPIAN_HOME/_admin/accdocs3/
• APPIAN_HOME/_admin/mini/
• APPIAN_HOME/_admin/models/
• APPIAN_HOME/_admin/plugins/
• APPIAN_HOME/_admin/process_notes/
• APPIAN_HOME/_admin/shared/
• APPIAN_HOME/server/archived-process/
• APPIAN_HOME/server/channels/gw1/
• APPIAN_HOME/server/collaboration/gw1/
• APPIAN_HOME/server/forums/gw1/
• APPIAN_HOME/server/msg/
• APPIAN_HOME/server/notifications/gw1/
• APPIAN_HOME/server/personalization/gw1/
• APPIAN_HOME/server/portal/gw1/
• APPIAN_HOME/server/process/analytics/0000/gw1/
• APPIAN_HOME/server/process/analytics/0001/gw1/
• APPIAN_HOME/server/process/analytics/0002/gw1/
• APPIAN_HOME/server/process/design/gw1/
• APPIAN_HOME/server/process/exec/00/gw1/
• APPIAN_HOME/server/process/exec/01/gw1/
• APPIAN_HOME/server/process/exec/02/gw1/

A symbolic link should do the job.

A symbolic link should do the job.

if a symbolic link is used; and let's say we are sharing the files across three servers (server1, server2 and server3)

will the link be in the following format?

Ln -s <Server1_File> <Nas_location>

Ln -s <Server2_File> <Nas_location>

Ln -s <Server2_File> <Nas_location>

in All three cases, the files on the servers will be pointing to the Nas location?

Also, since I am doing a new installation of appian on all the servers, folders like - APPIAN_HOME/_admin/accdocs1/, does not exist yet until appian services are started. Do I need to manually create these folders on the  servers?

Any advise will be appreciated.

Thanks

Hi Nicholas,

Yes the syntax of the symbolic link is correct. I assume you are referring to linking directories with the phrase <Server1_File>.
So you are going to point directories on the servers to the NAS which is correct.

Regarding the installation - my advise would be:
a) Install Appian and let the directories being created by Appian
b) Shut the platform down
c) If files already exists in those directories, copy them over to the accordingly directory on the NAS
d) Create the links for all the directories on the servers
e) Restart the Appian Platform and verify everything is working.  

You might also consider to share the logs as documented here:
https://docs.appian.com/suite/help/22.4/High_Availability_and_Distributed_Installations.html#shared-logs

Needless to say that the back-up strategy should also include the residing local files for Kafka, Zookeeper, Search Server and Data Server.