shared partition taking high memory of 98%, where zrd.out file consuming more data

Well the question would be is the ZRD Debug logging is enabled ? Was it enabled for some troubleshooting activity and missed to disable back.

The ZoneRunner process debug log is located at /var/tmp/zrd.out.

Can you check currently what's the logging level of zrd.

tmsh list /sys db log.zrd.level value

Notice is the default value, if you see it on debug mode, the 28GB file will continue to increase day-by-day. If its set back to notice, it means the debugging is stopped.

Refer article.

On a side note: Do a ls -ltr to know when this file was created, you go back and check what and when was happened.