multiple domains on the same server - reindexing issue

[Qahsan]

hello all - i have searched for this issue from the last few days and unable to find anyting. here is the problem, i have two domains abc.com and xyz.com both running on the same server/ip. 

using elastic search, varnish along with httpd. 

when i reindex abc.com(magento2.3.3) from the admin panel OR from the CLI it ruins the reindexing for xyz.com(magento2.4.1) and vice versa. Its like i can have only one domain reindexed at one point. 

i have cleared cahce, regenerated deployed static contents etc etc and no go yet. 

what am i doing wrong? thank you for your time.

[JLHC]

Are the two domains part of the same Magento installation or are they separate? 

Do they share the document root, any files or database?

[Qahsan]

abc.com is production (magento2.3.3)

xyz.com is testing (magento2.4.1)

basically we have installed magento2.4.1 and imported customers, products and orders db from abc to xyz because upgrading from 2.3.3 to 2.4.1 we encountered many issues. right now all is working on xyz.com just that when we reindex, its an issue.

Both are seperate domains. Both are seperate instance.

I am not sure if both are using the same elastic search, varnish and acpache or they are using seperate? they must be sharing the instances and that is why its doing what its doine becaise it wont make sense otherwise. varnish and eleastic search installed on root i believe. Does it automatcially provide local insance to each domain/account?

[Qahsan · Accepted solution]

after testing further i found the Solution:

stores->configurstion->catalog->catalog->catelog Search and add a new prefix in the eleastic search section

Every domain should be using its own prefix.