系統升級後，ZFS 數據集不再在重新啟動時自動掛載

我有一個 Arch linux ZFS 備份系統，它很長時間沒有更新，因為它執行良好，沒有理由打擾。但是，在最近一次升級之後，我的 ZFS 數據集在我重新啟動時不再自動掛載。不幸的是，這些服務沒有顯示任何錯誤消息，我可以執行

# zfs mount -a

系統啟動後沒有問題。一些細節：

[root@elephant etc]# uname -a
Linux elephant 4.16.11-1-ARCH #1 SMP PREEMPT Tue May 22 21:40:27 UTC 2018 x86_64 GNU/Linux
[root@elephant etc]# pacman -Q | grep spl
spl-dkms 0.7.9-1
spl-utils 0.7.9-1
[root@elephant etc]# pacman -Q | grep zfs
zfs-dkms 0.7.9-1
zfs-utils 0.7.9-1

root@elephant etc]# zfs get mountpoint backup/www
NAME                              PROPERTY    VALUE                              SOURCE
backup/www  mountpoint  /backup/www  default
[root@elephant etc]# zfs get mountpoint backup/data
NAME                               PROPERTY    VALUE                               SOURCE
backup/data  mountpoint  /backup/data  default
[root@elephant etc]# zfs get mountpoint backup/metadata
NAME             PROPERTY    VALUE             SOURCE
backup/metadata  mountpoint  /backup/metadata  default

特別注意 zfs-mount 服務似乎非常滿意：

[root@elephant ~]# systemctl -l status zfs*
● zfs.target - ZFS startup target
  Loaded: loaded (/usr/lib/systemd/system/zfs.target; enabled; vendor preset: enabled)
  Active: active since Mon 2018-05-28 15:30:18 CDT; 1min 32s ago

May 28 15:30:18 elephant systemd[1]: Reached target ZFS startup target.

● zfs-import-cache.service - Import ZFS pools by cache file
  Loaded: loaded (/usr/lib/systemd/system/zfs-import-cache.service; enabled; vendor preset: enabled)
  Active: active (exited) since Mon 2018-05-28 15:30:18 CDT; 1min 32s ago
 Process: 659 ExecStart=/usr/bin/zpool import -c /etc/zfs/zpool.cache -aN (code=exited, status=0/SUCCESS)
 Process: 656 ExecStartPre=/sbin/modprobe zfs (code=exited, status=0/SUCCESS)
Main PID: 659 (code=exited, status=0/SUCCESS)

May 28 15:30:12 elephant systemd[1]: Starting Import ZFS pools by cache file...
May 28 15:30:18 elephant systemd[1]: Started Import ZFS pools by cache file.

● zfs-zed.service - ZFS Event Daemon (zed)
  Loaded: loaded (/usr/lib/systemd/system/zfs-zed.service; enabled; vendor preset: enabled)
  Active: active (running) since Mon 2018-05-28 15:30:18 CDT; 1min 32s ago
    Docs: man:zed(8)
Main PID: 1586 (zed)
   Tasks: 3 (limit: 4915)
  Memory: 5.6M
  CGroup: /system.slice/zfs-zed.service
          └─1586 /usr/bin/zed -F

May 28 15:30:18 elephant systemd[1]: Started ZFS Event Daemon (zed).
May 28 15:30:18 elephant zed[1586]: ZFS Event Daemon 0.7.9-1 (PID 1586)
May 28 15:30:18 elephant zed[1586]: Processing events since eid=0
May 28 15:30:18 elephant zed[1591]: eid=1 class=history_event pool_guid=0x7314E37F1A1C0088
May 28 15:30:18 elephant zed[1593]: eid=2 class=config_sync pool_guid=0x7314E37F1A1C0088
May 28 15:30:18 elephant zed[1595]: eid=3 class=pool_import pool_guid=0x7314E37F1A1C0088
May 28 15:30:18 elephant zed[1618]: eid=5 class=config_sync pool_guid=0x7314E37F1A1C0088

● zfs-mount.service - Mount ZFS filesystems
  Loaded: loaded (/usr/lib/systemd/system/zfs-mount.service; enabled; vendor preset: enabled)
  Active: active (exited) since Mon 2018-05-28 15:30:12 CDT; 1min 38s ago
 Process: 657 ExecStart=/usr/bin/zfs mount -a (code=exited, status=0/SUCCESS)
Main PID: 657 (code=exited, status=0/SUCCESS)

May 28 15:30:12 elephant systemd[1]: Starting Mount ZFS filesystems...
May 28 15:30:12 elephant systemd[1]: Started Mount ZFS filesystems.
[root@elephant ~]#

然而：

[root@elephant ~]# zfs mount
[root@elephant ~]# 
[root@elephant ~]# zfs mount -a
[root@elephant ~]# zfs mount
backup                          /backup
backup/data  /backup/data
backup/metadata                 /backup/metadata
backup/www  /backup/www

我已經沒有時間來處理這個問題了，我只想將所有數據集切換到傳統掛載，但我仍然很好奇為什麼這適用於 zfs 0.6.x 但不適用於 0.7.9 - - 可能是某種系統不兼容？

原來我的問題是我沒有啟用zfs-import.target。當我第一次使用 ZoL 0.6.x 設置這個系統時，我什至不確定這個單元文件是否存在，但無論如何

systemctl enable zfs-import.target

解決了這個問題。ZFS 數據集在啟動時再次正確掛載。

引用自：https://serverfault.com/questions/914173