我的笔记本电脑上安装了 Ubuntu 16.04，同时还安装了 Windows。systemd-analyze blame名为“dev-sda7.device”的服务耗时太长。如何解决这个问题，或者我应该禁用它吗？
的结果systemd-analyze time
Startup finished in 4.207s (firmware) + 4.576s (loader) + 3.466s (kernel) + 33.899s (userspace) = 46.149s
的结果 systemd-analyze blame
16.326s dev-sda7.device
12.859s ufw.service
11.263s systemd-tmpfiles-setup-dev.service
7.935s NetworkManager-wait-online.service
3.203s keyboard-setup.service
2.736s vboxdrv.service
2.467s accounts-daemon.service
2.349s apache2.service
2.239s NetworkManager.service
2.163s ModemManager.service
1.963s lightdm.service
1.843s nmbd.service
1.749s samba-ad-dc.service
1.599s systemd-fsck@dev-disk-by\x2duuid-B053\x2dA56B.service
1.367s thermald.service
1.127s polkitd.service
1.112s systemd-journald.service
1.066s teamviewerd.service
1.007s udisks2.service
975ms apparmor.service
926ms plymouth-start.service
的结果cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
# / was on /dev/sda7 during installation
UUID=493cc833-193e-435d-840a-b862ca367fba / ext4 errors=remount-ro 0 1
# /boot/efi was on /dev/sda2 during installation
UUID=B053-A56B /boot/efi vfat umask=0077 0 1
# swap was on /dev/sda6 during installation
UUID=a49f56b1-53c3-4eaf-9460-0a221e59957a none swap sw 0 0
答案1
您无法禁用它，因为/dev/sda7这是挂载根分区的地方。在 systemd 中，它在启动时可以处理的所有内容都被放入 systemd 单元中。然后您可以使用它来执行操作（例如，在这种情况下跟踪计时，或依靠它来提供服务）。在设备的情况下，链条如下：
- 内核加载设备并激活它
- systemd 监视此情况并
/dev/sdxy为其创建节点 - 然后 systemd 激活从生成的各种挂载单元
fstab - 然后触发等待文件系统挂载的其他各种服务
- 等等
这确实可以让您识别出磁盘激活速度很慢，但除非您可以获得新磁盘，否则您对此无能为力。
您可以尝试分析关键路径，看看是否还有其他可以修复的问题：
systemd-analyze critical-chain [UNIT...] prints a tree of the
time-critical chain of units (for each of the specified UNITs or for
the default target otherwise). 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. Note that the output might be
misleading as the initialization of one service might depend on socket
activation and because of the parallel execution of units.
例子：
graphical.target @10.868s
└─multi-user.target @10.868s
└─squid-deb-proxy.service @10.816s +51ms
└─network-online.target @10.814s
└─NetworkManager-wait-online.service @2.419s +8.395s
└─NetworkManager.service @2.243s +155ms
└─dbus.service @2.192s
└─basic.target @2.129s
└─sockets.target @2.129s
└─snapd.socket @2.127s +1ms
└─sysinit.target @2.127s
└─swap.target @2.127s
└─dev-disk-by\x2duuid-498d24e5\x2d7755\x2d422f\x2dbe45\x2d1b78d50b44e8.swap @2.119s +7ms
└─dev-disk-by\x2duuid-498d24e5\x2d7755\x2d422f\x2dbe45\x2d1b78d50b44e8.device @2.119s
例如，就我的情况而言，网络启动速度很慢。