If you are one of the lucky owners of a Raspberry Pi and a SSD you might have heard of TRIM - or better the missing TRIM feature. As I learned from this excellent article by Jeff Geerling there is a good chance that it can be enabled with a few commands. You have to look up some numbers and end up with 2 commands specific for your setup (i.e. the combination of SSD plus adapter). They have to be executed after every boot.
Sometimes I have an urge to change components in my setup (like an SSD). Combined with my tendency to forget important dependencies (like hardcoded numbers) I needed a more adaptive solution. The Python script in this repository tries to follow the steps described by Jeff as close as possible. It works for me, but please be careful.
I'm using Ubuntu 20.04 with a Kingston A400 drive connected with a "renkforce USB 3.0 to SATA" adapter:
muhkuh@flashstation01:~$ lsusb
Bus 002 Device 002: ID 174c:55aa ASMedia Technology Inc. Name: ASM1051E SATA 6Gb/s bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge, ASM1153E SATA 6Gb/s bridge
...
And from dmesg:
[ 3.909785] usbcore: registered new interface driver usb-storage
[ 3.931434] scsi host0: uas
[ 3.935473] usbcore: registered new interface driver uas
[ 3.936003] scsi 0:0:0:0: Direct-Access KINGSTON SA400S37480G 0 PQ: 0 ANSI: 6
[ 3.953369] sd 0:0:0:0: Attached scsi generic sg0 type 0
[ 3.953955] sd 0:0:0:0: [sda] 937703088 512-byte logical blocks: (480 GB/447 GiB)
[ 3.966533] sd 0:0:0:0: [sda] Write Protect is off
[ 3.971381] sd 0:0:0:0: [sda] Mode Sense: 43 00 00 00
[ 3.975334] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 3.989386] sd 0:0:0:0: [sda] Optimal transfer size 33553920 bytes
The script has 1 argument, which is the device to activate TRIM for. My SSD appears at /dev/sda, so my device is sda and I run the script like this:
python3 sda
The script first checks if TRIM is not yet active. Then it looks up the values and constructs the commands necessary for the activation:
muhkuh@flashstation01:~$ sudo python3 trim.py sda
TRIM is not enabled for sda.
Set the provisioning mode in /sys/devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb2/2-2/2-2:1.0/host0/target0:0:0/0:0:0:0/scsi_disk/0:0:0:0/provisioning_mode to "unmap".
Setting the maximum number of bytes to discard in /sys/class/block/sda/queue/discard_max_bytes to 2147450880
muhkuh@flashstation01:~$ sudo python3 trim.py sda
TRIM is enabled for sda.
There is also a service file for systemd to automate the start. Replace the ENTER_DEVICE_HERE part in enable_trim.service with your device and copy it to one of the folders with service files, for example /etc/systemd/system. Copy the script trim.py to /usr/local/bin/ and enable the script:
sudo systemctl enable enable_trim.service
After a reboot TRIM should be active. Check it with...
muhkuh@flashstation01:~$ systemctl status enable_trim.service
● enable_trim.service - Activate TRIM for SSD
Loaded: loaded (/etc/systemd/system/enable_trim.service; enabled; vendor preset: enabled)
Active: active (exited) since Thu 2021-07-15 23:42:55 CEST; 45s ago
Process: 1496 ExecStart=/usr/bin/python3 /usr/local/bin/trim.py sda (code=exited, status=0/SUCCESS)
Main PID: 1496 (code=exited, status=0/SUCCESS)
Jul 15 23:42:55 flashstation01 systemd[1]: Starting Activate TRIM for SSD...
Jul 15 23:42:55 flashstation01 python3[1496]: TRIM is not enabled for sda.
Jul 15 23:42:55 flashstation01 python3[1496]: Set the provisioning mode in /sys/devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb2/2-2/2-2:1.0/host0/target0:0:0/0:0:0:0/scsi_di>
Jul 15 23:42:55 flashstation01 python3[1496]: Setting the maximum number of bytes to discard in /sys/class/block/sda/queue/discard_max_bytes to 2147450880
Jul 15 23:42:55 flashstation01 systemd[1]: Finished Activate TRIM for SSD.
Finally a sudo systemctl enable fstrim.timer enables automatic trimming.