I have enabled TRIM by adding discard option in /etc/fstab but even after removing it the effect is not going. How to disable it?
In 14.04 there is an automativ weekly trim. You can disable it with:
Disabling trim is very important for legacy servers that pre-date SATA. SSD's can be fitted for power, reliability as well as some speed increase by means of an IDE to SATA bridge or converter. Or a DOM package plugged directly into the MB.
Some of these hang on TRIM. Random writes to the SSD are 3-4 times faster than UDMA so TRIM does not matter, it has time to write twice.
My approach is to comment out /etc/cron.weekly/fstrim (c. Utopic or Trusty LTS)
Of course this will also affect SATA SSD's on a PCI expansion card, but that's something else.