Small Files Backup

Hello Experts,

I was reading that small files backup could hamper backup performance when files are more than 1 Millions.

So my question is when we configure flash backup.

1:-Do we only need to select the flash backup type in policy or we need to do some more configuration?

2:-Pls let me know the requirement and configurations steps?

3:-Pls also let me know why do the small files take lot of time to take backup?

Thanks so much.....