The default reserved blocks percentage for ext filesystems is 5%. On a 4TB data drive this is 200GB which seems excessive to me.
Obviously this can be adjusted with tune2fs:
tune2fs -m <reserved percentage> <device>
however the man page for tune2fs states that one of the reasons for these reserved blocks is to avoid fragmentation.
So given the following (I have tried to be specific to avoid wildly varying opinions):
- ~4TB HDD
- Used to store large files (all >500mb)
- Once full, Very few writes (maybe once a month 1-5 files are replaced)
- Data only (no OS or applications running from the drive)
- Moderate reads (approx 20tb a week and the whole volume read every 3 months)
- HDD wear is of concern and killing a HDD for the sake of saving 20GB is not the desired outcome (Is this even a concern?)
What is the maximum percentage that the drive can be filled to without causing (noticeable from a performance and/or hdd wear perspective) fragmentation?
Are there any other concerns with filling a large data hdd to a high percentage and/or setting the reserved blocks count to say 0.1%?