====== Using a SSD as Boot Device ====== If you are lucky enough to have a SSD drive available as boot device you'll certainly want to use it.\\ One important fact to know about SSDs is that you need to "clean" them on a regular basis to maintain top performances. This is done using the TRIM command: TRIM allows the OS to "inform a solid-state drive (SSD) which blocks of data are no longer considered in use and can be wiped internally". Without using TRIM, the SSD speed decreases after a while so if you have a solid-state drive that supports TRIM, you should enable it so your SSD remains fast over time. ===== Determine if Your SSD supports TRIM ===== You first need to make sure that your SSD supports the TRIM command, to do that use the following commands: <code> sudo hdparm -I /dev/sda | grep "TRIM" </code> You might have to use another device identifier than// /dev/sda// for you it might be// /dev/sdb// or// /dev/sdc//. To get your disk identifier, use: <code> sudo fdisk -l </code> ===== fstab or cron ? ===== ==== Online discard in fstab ==== Although using online discard (in fstab) seems to be **NOT RECOMMENDED**, in case you really want to use this technique, open /etc/fstab as root with a text editor: <code> sudo nano /etc/fstab </code> And add the "discard" option (separated by a comma and no space!) to the SSD partitions you want to enable TRIM for. Here's an example: <code> <file system> <mount point> <type> <options> <dump> <pass> # / was on /dev/sdb1 during installation UUID=1cd2fc4f-7d99-4c7a-8ea7-6f9a2d5e5960 / ext4 discard,errors=remount-ro 0 1 </code> ==== Using a daily cron job ==== Using a timed cron job, the SSD trimming will occur on a regular basis you decide of (daily is probably a good choice). **This is the recommended way to TRIM your SSD**. To use a daily cron job (so the trimming will occur once a day) for TRIM (fstrim), open /etc/cron.daily/trim as root with a text editor (/etc/cron.daily/trim doesn't exist so this will create the file): <code> sudo nano /etc/cron.daily/trim </code> and paste this: <code> #!/bin/sh LOG=/var/log/trim.log echo "*** $(date -R) ***" >> $LOG fstrim -v / >> $LOG fstrim -v /home >> $LOG </code> The last two commands in the code above perform the actual trimming for the root (/) and home (/home) partition and you need to edit them: here, add the SSD partitions for which you want to enable the daily TRIM job (usually, you must add "/" if the root partition is on the SSD and "/home" if you've set up a separate home partition). Before saving the file, you can check if the fstrim command works: <code> sudo fstrim -v / </code> The output should look similar to this: <code> sudo fstrim -v / /: 8158715904 bytes were trimmed </code> Once you've added your SSD partitions, save the file and make it executable using the following command: <code> sudo chmod +x /etc/cron.daily/trim </code> The system executes the daily cron (using anacron, even if your computer is turned off at that time, the job will still be performed later on) jobs at around 06:25 so each day after that time, you can check the /var/log/trim.log log file to see the fstrim output. reference: [[http://www.webupd8.org/2013/01/enable-trim-on-ssd-solid-state-drives.html]]