Thanks once again.

I have changed log backup frequency to every hour and

I was looking log backup size on my backup drive and it shows for each hour after changing:

8 AM 7013 KB

9 AM24897 KB

10 AM45385 KB

11 AM43220 KB

12 PM419318 KB

I have just checked - select name,log_reuse_wait_desc from sys.databases and log_reuse_wait_desc shows Log_backup and also checking to VLfs, total files around 490 and 33 files with status = 2.

Also ran, DBCC SQLPERF(LogSpace):

Log Size (MB) Log Space Used (%) Status

14198.80.17199950