我的 Ubuntu 启动时间太长。以下是详细信息
systemd-analyze critical-chain
The time after the unit is active or started is printed after the "@" character.
The time the unit takes to start is printed after the "+" character.
graphical.target @48.421s
└─multi-user.target @48.421s
└─mysql.service @31.396s +10.665s
└─network.target @31.396s
└─NetworkManager.service @27.448s +3.946s
└─dbus.service @27.050s
└─basic.target @27.027s
└─sockets.target @27.027s
└─snapd.socket @26.954s +72ms
└─sysinit.target @26.953s
└─systemd-timesyncd.service @26.800s +152ms
└─systemd-tmpfiles-setup.service @26.295s +496ms
└─local-fs.target @26.292s
└─run-snapd-ns-canonical\x2dlivepatch.mnt.mount @39.370s
└─run-snapd-ns.mount @37.513s
└─local-fs-pre.target @4.757s
└─keyboard-setup.service @2.515s +2.242s
└─systemd-journald.socket @2.514s
└─system.slice @2.514s
└─-.slice @2.512s
还有一个
systemd-analyze blame
22.760s dev-sda7.device
21.089s systemd-journal-flush.service
17.017s plymouth-quit-wait.service
12.578s systemd-udevd.service
12.280s snap-gnome\x2dcalculator-180.mount
12.259s snap-gnome\x2dcalculator-238.mount
12.040s snap-gnome\x2dcharacters-139.mount
10.665s mysql.service
8.305s plymouth-start.service
5.958s NetworkManager-wait-online.service
3.946s NetworkManager.service
3.375s snapd.service
3.125s udisks2.service
..................
看起来dev-sda7.device正在产生问题。请指导我如何最大限度地缩短启动时间。