Reduce the stress on SSD

If you have an SSD, you better do some adjustments to increase the lifetime of your harddrive.

1) Mounting your partitions with trim support.

/dev/sda1       /               ext4                  defaults,relatime,noatime,discard            0 1 
/dev/sda2       /               ext4                  defaults,relatime,noatime,discard            0 1 


2) Use your ram for temp files.

tmpfs             /tmp        tmpfs                  noatime,nodiratime,size=6G           0 0 


 3) If you are running gentoo (sabayon) on desktop, many programs, using X windows systems (like: chromium, firefox, skype) are making frequent disk I/O every few seconds to cache. Default cache dir is ~/.cache, which is on hard drive.

Edit 
/etc/env.d/30xdg-data-local and add line: 
XDG_CACHE_HOME="/tmp/.cache" 

Reboot

TEST TRIM

Now it is time to test trim on SSD. As root,

su
dd if=/dev/urandom of=tempfile count=100 bs=512k oflag=direct

Check the starting LBA address of the file:

hdparm --fibmap tempfile

Read the first address of the file, note that you need to put the first LBA in place of [ADDRESS]:

hdparm --read-sector [ADDRESS] /dev/sdX

Now remove the file and synchronize the filesystem:

rm tempfile

sync

Use the same command to re-read the LBA:

hdparm --read-sector [ADDRESS] /dev/sdX

If TRIM is properly working the result of the last command should be a bunch of zeros. If the output is not zeros, then something could be wrong with your kernel/Ext4 configuration and TRIM may not be working.

References
1) https://wiki.gentoo.org/wiki/SSD