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使用 lvmvdo 创建 ramdisk 并在重启后持久保留？

tag-icon • tag-icon filesystems lvm rhel8 ramdisk
使用 lvmvdo 创建 ramdisk 并在重启后持久保留？

我正在尝试使用 lvmvdo 和下面的单元文件创建一个持久的 ramdisk，但它似乎不起作用。我--type vdo还没有向 lvcreate 命令添加该选项（这是RHEL9）

[mukesh@server1 ~]$ sudo cat /etc/systemd/system/my_lvm.service 
[Unit]
Description=Create and mount LVM logical volume

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/bin/bash -c 'mknod /dev/ram0 b 1 0; \
  pvcreate /dev/ram0; \
  vgcreate my_vg /dev/ram0; \
  lvcreate -n my_lv -L 100M my_vg; \
  mkfs.ext4 /dev/my_vg/my_lv; \
  mount /dev/my_vg/my_lv /mnt/ramdisk'

[Install]
WantedBy=multi-user.target

好的，我做了一些更改（我使用brd内核模块代替mknod），现在 ExecStart 工作正常，但 ExecStop 不起作用。

[mukesh@server1 ~]$ cat /etc/systemd/system/my_lvm.service 
[Unit]
Description=Create and mount LVM logical volume

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/bin/bash -c 'pvcreate /dev/ram0; \
  vgcreate my_vg /dev/ram0; \
  lvcreate -n my_lv -L 80M my_vg; \
  mkfs.ext4 /dev/my_vg/my_lv; \
  mount /dev/my_vg/my_lv /mnt/ramdisk'

ExecStop=/bin/bash -c 'umount /mnt/ramdisk; \
  lvremove -yff /dev/my_vg/my_lv; \
  vgremove -yff my_vg; \
  wipefs /dev/ram0; \
  pvremove -yff /dev/ram0'

[Install]
WantedBy=multi-user.target

更新错误：输出journalctl -xeu my_lvm.service

Feb 14 15:05:40 server1.example.com bash[2881]:   Logical volume my_vg/my_lv contains a filesystem in use.
Feb 14 15:05:40 server1.example.com bash[2882]:   Logical volume my_vg/my_lv contains a filesystem in use.
Feb 14 15:05:40 server1.example.com bash[2883]: DEVICE OFFSET TYPE        UUID                                   LABEL
Feb 14 15:05:40 server1.example.com bash[2883]: ram0   0x218  LVM2_member nEmZLv-x6eJ-WnQV-JIpq-zbK5-EsXA-fEhFqM
Feb 14 15:05:40 server1.example.com bash[2878]:   WARNING: PV /dev/ram0 is used by VG my_vg.
Feb 14 15:05:40 server1.example.com bash[2878]:   WARNING: Wiping physical volume label from /dev/ram0 of volume group "my_vg".
Feb 14 15:05:40 server1.example.com bash[2878]:   Can't open /dev/ram0 exclusively.  Mounted filesystem?
Feb 14 15:05:40 server1.example.com bash[2878]:   Can't open /dev/ram0 exclusively.  Mounted filesystem?
Feb 14 15:05:40 server1.example.com bash[2878]:   Error opening device /dev/ram0 for reading at 0 length 4096.
Feb 14 15:05:40 server1.example.com bash[2878]:   Cannot use /dev/ram0: device has a signature
Feb 14 15:05:40 server1.example.com systemd[1]: my_lvm.service: Control process exited, code=exited, status=5/NOTINSTALLED
Feb 14 15:05:40 server1.example.com systemd[1]: my_lvm.service: Failed with result 'exit-code'.
Feb 14 15:05:40 server1.example.com systemd[1]: Stopped Create and mount LVM logical volume.

答案1

这似乎满足了我的要求，似乎没有任何问题。除非有更好的方法来做到这一点。

[munish259272@munish259272example ~]$ cat /etc/modules-load.d/brd.conf
brd
[munish259272@munish259272example ~]$ cat /etc/modprobe.d/brd.conf 
options brd rd_nr=1 rd_size=73400320 max_part=1
[munish259272@munish259272example ~]$ lsmod | grep brd
brd                    16384  1
[munish259272@munish259272example ~]$

单元文件：

[Unit]
Description=Create and mount LVM logical volume

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/bin/bash -c 'pvcreate /dev/ram0; \
  vgcreate my_vg /dev/ram0; \
  lvcreate --type vdo -n my_lv -l 17919 -V 700G  --config "allocation/vdo_slab_size_mb=1024" my_vg; \
  mkfs.ext4 -K /dev/my_vg/my_lv; \
  mount /dev/my_vg/my_lv /mnt/ramdisk; \
  lvmdevices -y --deldev /dev/ram0'


[Install]
WantedBy=multi-user.target

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