SSD/NVMe Tweaks (TRIM/Discard)

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Note, with­in the ex­am­ples in the fol­low­ing sec­tions, /​​​dev/​​​sda refers to a SSD de­vice while /​​​dev/​​​nvme0n1 refers to a NVMe de­vice.

Get Full SSD/​​​NVMe De­vice In­fo

For SSD de­vices use: 

smartctl -x /dev/sda            # -x, --xall; -a, --all

hdparm -I /dev/sda              # doesn't support NVMe

For NVMe de­vices use: 

smartctl -x /dev/nvme0n1        # -x, --xall; -a, --all

nvme smart-log -H /dev/nvme0n1  # apt install nvme-cli

Ref­er­ences

Block Dis­card Op­er­a­tions

[Batch dis­card] TRIM from CLI

fstrim com­mand

sudo fstrim -av             # trim/discardd all mounted devices, verbose output
sudo fstrim -v /            # trim/discardd the root fs, verbose output
sudo fstrim /mount-point    # trim/discardd a device mounted at specific mount point

Prox­moxVE Node

For unpriv­i­leged Lin­ux con­tain­ers use the fol­low­ing com­mand at the Prox­moxVE host side .

pct fstrim 151              # Where 151 is the Id of the container

For priv­i­leged con­tain­ers fstrim could be ex­e­cut­ed al­so from the guest's side. For the vir­tu­al ma­chines – en­able the dis­card and SSD em­u­la­tion op­tions in the stor­age de­vice con­fig­u­ra­tion, use Vir­tIo SC­SI as con­troller and trim at the guest side. Al­so we can use one of the fol­low­ing com­mands at he Prox­moxVE host side.

qm guest cmd 251 fstrim     # Where 251 is the Id of the container

qm agent 251 fstrim         # Where 251 is the Id of the container

Ref­er­ences

[Pe­ri­od­ic Dis­card] Set the TRIM Job to Dai­ly

sudo systemctl enable fstrim.timer

sudo mkdir /etc/systemd/system/fstrim.timer.d
sudo nano /etc/systemd/system/fstrim.timer.d/override.conf

[Timer]
OnCalendar=
OnCalendar=daily

Re­boot the sys­tem or do dae­mon-re­load and check the up­dat­ed val­ue.

sudo systemctl daemon-reload

systemctl cat fstrim.timer

# /lib/systemd/system/fstrim.timer
[Unit]
Description=Discard unused blocks once a week
Documentation=man:fstrim
ConditionVirtualization=!container

[Timer]
OnCalendar=weekly
AccuracySec=1h
Persistent=true

[Install]
WantedBy=timers.target

# /etc/systemd/system/fstrim.timer.d/override.conf
[Timer]
OnCalendar=
OnCalendar=daily

sudo systemctl status fstrim.service
sudo systemctl status fstrim.timer

Un­do the change if you need.

sudo rm -v /etc/systemd/system/fstrim.timer.d/override.conf

Ref­er­ences

[On­line Dis­card] En­able TRIM in /​​​etc/​​​fstab

TRIM (Trim com­mand let an OS know which SSD blocks are not be­ing used and can be cleared).

sudo nano /etc/fstab

#/dev/disk/by-uuid/09e7c8ed-fb55-4a44-8be4-18b1696fc714 / ext4 defaults 0 0
/dev/disk/by-uuid/09e7c8ed-fb55-4a44-8be4-18b1696fc714 / ext4 discard,async,noatime,nodiratime,errors=remount-ro 0 1

Warn­ing: Users need to be cer­tain that their SSD sup­ports TRIM be­fore at­tempt­ing to use it. Da­ta loss can oc­cur oth­er­wise! Tp test whether the SSD de­vice sup­ports TRIM/​​​Discard op­tion you can use ei­ther of the fol­low­ing com­mands. 

sudo hdparm -I /dev/sda | grep TRIM

* Data Set Management TRIM supported (limit 8 blocks)

sudo smartctl --all /dev/sda | grep TRIM

TRIM Command:     Available

To test does an NVMe sup­ports TRIM (phys­i­cal dis­card op­tion) the out­put of the fol­low­ing com­mand must be greater than 0. This ap­proach is ap­plic­a­ble al­so for SSD de­vices.

cat /sys/block/nvme0n1/queue/discard_max_bytes

cat /sys/block/sda/queue/discard_max_bytes

Ref­er­ences

Tweak the AMP val­ue of SSD

Most Lin­ux dis­tri­b­u­tions use Lin­ux Kernel’s “Ad­vanced Pow­er Man­age­ment (APM)” API to han­dle con­fig­u­ra­tion, op­ti­mize per­for­mance, and en­sure sta­bil­i­ty of stor­age de­vices. These de­vices are as­signed an APM val­ue be­tween 1 and 255 to con­trol their pow­er man­age­ment thresh­olds. A val­ue of 254 in­di­cates best per­for­mance, while a val­ue of 1 in­di­cates bet­ter pow­er man­age­ment. As­sign­ing a val­ue of 255 will dis­able APM al­to­geth­er. By de­fault, SS­Ds are as­signed an APM of 254 when the sys­tem is run­ning on ex­ter­nal pow­er. In bat­tery mode, the APM lev­el is set to 128, re­duc­ing the read and write speeds of SS­Ds. This ar­ti­cle ex­plains how to in­crease SSD APM lev­els to 254 when your Lin­ux lap­top is run­ning on bat­tery mode. 

sudo hdparm -B254 /dev/sda

Get the cur­rent AMP val­ue.

sudo hdparm -B /dev/sda

Test the per­for­mance. 

sudo hdparm -tT /dev/sda

Ref­er­ences

See al­so


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