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当前速读:Linux LVM磁盘分区管理

来源:博客园


【资料图】

源文档地址:https://www.2daygeek.com/create-lvm-storage-logical-volume-manager-in-linux/

1. 创建PV创建前/dev/sdb不能分区,如果已经分区,使用fdisk /dev/sdb 删除分区
[root@O-Friday ~]# pvcreate /dev/sdb /dev/sdc    WARNING: dos signature detected on /dev/sdb at offset 510. Wipe it? [y/n]: y      Wiping dos signature on /dev/sdb.    WARNING: dos signature detected on /dev/sdc at offset 510. Wipe it? [y/n]: y      Wiping dos signature on /dev/sdc.      Physical volume "/dev/sdb" successfully created.      Physical volume "/dev/sdc" successfully created.    [root@O-Friday ~]# pvdisplay      --- Physical volume ---      PV Name               /dev/sda2      VG Name               openeuler      PV Size               <98.00 GiB / not usable 3.00 MiB      Allocatable           yes (but full)      PE Size               4.00 MiB      Total PE              25087      Free PE               0      Allocated PE          25087      PV UUID               Yv3d0c-OjcH-8s93-MsfZ-1JUu-XwU3-NYyPYD          "/dev/sdb" is a new physical volume of "10.00 GiB"      --- NEW Physical volume ---      PV Name               /dev/sdb      VG Name      PV Size               10.00 GiB      Allocatable           NO      PE Size               0      Total PE              0      Free PE               0      Allocated PE          0      PV UUID               AxdYk0-Giiv-kF4Z-QOIj-yA6j-Rsf0-BI7S2o          "/dev/sdc" is a new physical volume of "10.00 GiB"      --- NEW Physical volume ---      PV Name               /dev/sdc      VG Name      PV Size               10.00 GiB      Allocatable           NO      PE Size               0      Total PE              0      Free PE               0      Allocated PE          0      PV UUID               Nz06rK-h4FH-Jy2v-hXuE-hiws-6SRW-PSMQez
2. 创建VGvgname = openeuler是系统安装时自动创建
[root@O-Friday ~]# vgcreate vg01 /dev/sdb /dev/sdc      Volume group "vg01" successfully created    [root@O-Friday ~]# vgdisplay      --- Volume group ---      VG Name               vg01      System ID      Format                lvm2      Metadata Areas        2      Metadata Sequence No  1      VG Access             read/write      VG Status             resizable      MAX LV                0      Cur LV                0      Open LV               0      Max PV                0      Cur PV                2      Act PV                2      VG Size               19.99 GiB      PE Size               4.00 MiB      Total PE              5118      Alloc PE / Size       0 / 0      Free  PE / Size       5118 / 19.99 GiB      VG UUID               oAbeGg-j8U2-kCuO-tcmW-HQWv-MqbT-kQdipr          --- Volume group ---      VG Name               openeuler      System ID      Format                lvm2      Metadata Areas        1      Metadata Sequence No  3      VG Access             read/write      VG Status             resizable      MAX LV                0      Cur LV                2      Open LV               2      Max PV                0      Cur PV                1      Act PV                1      VG Size               <98.00 GiB      PE Size               4.00 MiB      Total PE              25087      Alloc PE / Size       25087 / <98.00 GiB      Free  PE / Size       0 / 0      VG UUID               I7kRIn-4XeX-0agf-OxRq-ehSi-hqJf-nvkmtU    
3. 查看vg
[root@O-Friday ~]# vgs vg01      VG   #PV #LV #SN Attr   VSize  VFree      vg01   2   0   0 wz--n- 19.99g 19.99g
4. 扩展VG
[root@O-Friday ~]# vgextend vg01 /dev/sdd    WARNING: dos signature detected on /dev/sdd at offset 510. Wipe it? [y/n]: y      Wiping dos signature on /dev/sdd.      Physical volume "/dev/sdd" successfully created.      Volume group "vg01" successfully extended    
5. 创建LV/swap 与 /root为安装系统时自动创建
[root@O-Friday ~]# lvcreate -n lv001 -L 15G vg01      Logical volume "lv001" created.    [root@O-Friday ~]# lvdisplay      --- Logical volume ---      LV Path                /dev/vg01/lv001      LV Name                lv001      VG Name                vg01      LV UUID                0TdOKB-PDI3-LWDv-X2nb-lBVV-kfLJ-jVOVBy      LV Write Access        read/write      LV Creation host, time O-Friday, 2023-03-15 14:24:07 +0800      LV Status              available      # open                 0      LV Size                15.00 GiB      Current LE             3840      Segments               2      Allocation             inherit      Read ahead sectors     auto      - currently set to     8192      Block device           253:2          --- Logical volume ---      LV Path                /dev/openeuler/swap      LV Name                swap      VG Name                openeuler      LV UUID                xNBLth-zrQf-HY8L-fSrA-jrrU-qERF-xfDafa      LV Write Access        read/write      LV Creation host, time O-Friday, 2023-03-05 10:52:53 +0800      LV Status              available      # open                 2      LV Size                6.00 GiB      Current LE             1536      Segments               1      Allocation             inherit      Read ahead sectors     auto      - currently set to     8192      Block device           253:1          --- Logical volume ---      LV Path                /dev/openeuler/root      LV Name                root      VG Name                openeuler      LV UUID                i3ZktA-EN9t-HJB3-y1Ok-Or1X-z0uq-3ixcbG      LV Write Access        read/write      LV Creation host, time O-Friday, 2023-03-05 10:52:54 +0800      LV Status              available      # open                 1      LV Size                <92.00 GiB      Current LE             23551      Segments               1      Allocation             inherit      Read ahead sectors     auto      - currently set to     8192      Block device           253:0    
6. 查看lv
[root@O-Friday ~]# lvs /dev/vg01/lv001      LV    VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert      lv001 vg01 -wi-a----- 15.00g    
7. 使用PE size 创建lv
15GB = 15360MB / 4MB (PE Size) = 3840 PEs        lvcreate -n lv001 -l 3840 vg01
8. 使用比例创建
lvcreate -n lv001 -l 100%FREE vg01     
9. 创建File system
mkfs -t ext4 /dev/vg01/lv001    mkfs -t xfs /dev/vg01/lv001        两种文件系统格式创建,下面使用ext4        [root@O-Friday ~]# lvs /dev/vg01/lv001      LV    VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert      lv001 vg01 -wi-a----- 15.00g    [root@O-Friday ~]# mkfs -t ext4 /dev/vg01/lv001    mke2fs 1.46.4 (18-Aug-2021)    Creating filesystem with 3932160 4k blocks and 983040 inodes    Filesystem UUID: 81d59fcc-ebac-430e-8eca-c36ed3155160    Superblock backups stored on blocks:            32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208        Allocating group tables: done    Writing inode tables: done    Creating journal (16384 blocks): done    Writing superblocks and filesystem accounting information: done            
10. 从lvm中移除物理卷 要移除的物理卷,used必须为0,如果要移除/dev/sdd首先通过pvmove将数据移动到其他物理卷 如果没有空闲的空间来移动数据,需要添加新的物理卷后,再移除原物理卷
[root@O-Friday ~]# pvs -o+pv_used       PV         VG        Fmt  Attr PSize   PFree   Used       /dev/sda2  openeuler lvm2 a--  <98.00g      0  <98.00g       /dev/sdb   vg01      lvm2 a--  <10.00g      0  <10.00g       /dev/sdc   vg01      lvm2 a--  <10.00g <10.00g      0       /dev/sdd   vg01      lvm2 a--  <10.00g   4.99g   5.00g            [root@O-Friday ~]# pvmove /dev/sdd       /dev/sdd: Moved: 1.72%       /dev/sdd: Moved: 100.00%     [root@O-Friday ~]# pvs -o+pv_used       PV         VG        Fmt  Attr PSize   PFree   Used       /dev/sda2  openeuler lvm2 a--  <98.00g      0  <98.00g       /dev/sdb   vg01      lvm2 a--  <10.00g      0  <10.00g       /dev/sdc   vg01      lvm2 a--  <10.00g   4.99g   5.00g       /dev/sdd   vg01      lvm2 a--  <10.00g <10.00g      0          [root@O-Friday ~]# pvremove /dev/sdd       PV /dev/sdd is used by VG vg01 so please use vgreduce first.       (If you are certain you need pvremove, then confirm by using --force twice.)       /dev/sdd: physical volume label not removed.          此时依然不能移除,因为pv在vg中已经使用,需要先用vgreduce删除     [root@O-Friday ~]# vgreduce vg01 /dev/sdd       Removed "/dev/sdd" from volume group "vg01"     [root@O-Friday ~]# pvremove /dev/sdd       Labels on physical volume "/dev/sdd" successfully wiped.     
11. 如何删除逻辑卷
如果已经挂载分区先执行umount /data     如果已经/etc/fstab设置了自动挂载, 要先删除          Disable the “lv001” logical volume          执行后查看lv status 已经是 not available状态          [root@O-Friday ~]# lvchange -an /dev/vg01/lv001     [root@O-Friday ~]# lvdisplay       --- Logical volume ---       LV Path                /dev/vg01/lv001       LV Name                lv001       VG Name                vg01       LV UUID                0TdOKB-PDI3-LWDv-X2nb-lBVV-kfLJ-jVOVBy       LV Write Access        read/write       LV Creation host, time O-Friday, 2023-03-15 14:24:07 +0800       LV Status              NOT available       LV Size                15.00 GiB       Current LE             3840       Segments               2       Allocation             inherit       Read ahead sectors     auto            --- Logical volume ---       LV Path                /dev/openeuler/swap       LV Name                swap       VG Name                openeuler       LV UUID                xNBLth-zrQf-HY8L-fSrA-jrrU-qERF-xfDafa       LV Write Access        read/write       LV Creation host, time O-Friday, 2023-03-05 10:52:53 +0800       LV Status              available       # open                 2       LV Size                6.00 GiB       Current LE             1536       Segments               1       Allocation             inherit       Read ahead sectors     auto       - currently set to     8192       Block device           253:1            --- Logical volume ---       LV Path                /dev/openeuler/root       LV Name                root       VG Name                openeuler       LV UUID                i3ZktA-EN9t-HJB3-y1Ok-Or1X-z0uq-3ixcbG       LV Write Access        read/write       LV Creation host, time O-Friday, 2023-03-05 10:52:54 +0800       LV Status              available       # open                 1       LV Size                <92.00 GiB       Current LE             23551       Segments               1       Allocation             inherit       Read ahead sectors     auto       - currently set to     8192       Block device           253:0     
12. 删除VG If there are no logical volumes associated with the volume group(VG) and if the VG is no longer required, then remove that as well.
[root@O-Friday ~]# vgchange -an vg01       0 logical volume(s) in volume group "vg01" now active     [root@O-Friday ~]# vgdisplay       --- Volume group ---       VG Name               vg01       System ID       Format                lvm2       Metadata Areas        2       Metadata Sequence No  11       VG Access             read/write       VG Status             resizable       MAX LV                0       Cur LV                0       Open LV               0       Max PV                0       Cur PV                2       Act PV                2       VG Size               19.99 GiB       PE Size               4.00 MiB       Total PE              5118       Alloc PE / Size       0 / 0       Free  PE / Size       5118 / 19.99 GiB       VG UUID               oAbeGg-j8U2-kCuO-tcmW-HQWv-MqbT-kQdipr            --- Volume group ---       VG Name               openeuler       System ID       Format                lvm2       Metadata Areas        1       Metadata Sequence No  3       VG Access             read/write       VG Status             resizable       MAX LV                0       Cur LV                2       Open LV               2       Max PV                0       Cur PV                1       Act PV                1       VG Size               <98.00 GiB       PE Size               4.00 MiB       Total PE              25087       Alloc PE / Size       25087 / <98.00 GiB       Free  PE / Size       0 / 0       VG UUID               I7kRIn-4XeX-0agf-OxRq-ehSi-hqJf-nvkmtU          [root@O-Friday ~]# vgremove vg01       Volume group "vg01" successfully removed     [root@O-Friday ~]# vgdisplay       --- Volume group ---       VG Name               openeuler       System ID       Format                lvm2       Metadata Areas        1       Metadata Sequence No  3       VG Access             read/write       VG Status             resizable       MAX LV                0       Cur LV                2       Open LV               2       Max PV                0       Cur PV                1       Act PV                1       VG Size               <98.00 GiB       PE Size               4.00 MiB       Total PE              25087       Alloc PE / Size       25087 / <98.00 GiB       Free  PE / Size       0 / 0       VG UUID               I7kRIn-4XeX-0agf-OxRq-ehSi-hqJf-nvkmtU     
13. 删除pv Delete physical volumes used for volume group **“vg01”**:
[root@O-Friday ~]# pvremove /dev/sdb /dev/sdc       Labels on physical volume "/dev/sdb" successfully wiped.       Labels on physical volume "/dev/sdc" successfully wiped.     [root@O-Friday ~]# pvdisplay       --- Physical volume ---       PV Name               /dev/sda2       VG Name               openeuler       PV Size               <98.00 GiB / not usable 3.00 MiB       Allocatable           yes (but full)       PE Size               4.00 MiB       Total PE              25087       Free PE               0       Allocated PE          25087       PV UUID               Yv3d0c-OjcH-8s93-MsfZ-1JUu-XwU3-NYyPYD     
14. 缩减逻辑卷大小 如果已经挂载, 先umount
[root@O-Friday mapper]# resize2fs /dev/mapper/vg01-lv001 20G     resize2fs 1.46.4 (18-Aug-2021)     Please run "e2fsck -f /dev/mapper/vg01-lv001" first.          [root@O-Friday mapper]# e2fsck -f /dev/mapper/vg01-lv001     e2fsck 1.46.4 (18-Aug-2021)     Pass 1: Checking inodes, blocks, and sizes     Pass 2: Checking directory structure     Pass 3: Checking directory connectivity     Pass 4: Checking reference counts     Pass 5: Checking group summary information     /dev/mapper/vg01-lv001: 11/1966080 files (0.0% non-contiguous), 167453/7861248 blocks     [root@O-Friday mapper]# resize2fs /dev/mapper/vg01-lv001 20G     resize2fs 1.46.4 (18-Aug-2021)     Resizing the filesystem on /dev/mapper/vg01-lv001 to 5242880 (4k) blocks.     The filesystem on /dev/mapper/vg01-lv001 is now 5242880 (4k) blocks long.          [root@O-Friday mapper]# lvreduce -L 20G /dev/mapper/vg01-lv001       WARNING: Reducing active logical volume to 20.00 GiB.       THIS MAY DESTROY YOUR DATA (filesystem etc.)     Do you really want to reduce vg01/lv001? [y/n]: y       Size of logical volume vg01/lv001 changed from <29.99 GiB (7677 extents) to 20.00 GiB (5120 extents).       Logical volume vg01/lv001 successfully resized.     [root@O-Friday mapper]# lsblk     NAME               MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS     sda                  8:0    0  100G  0 disk     ├─sda1               8:1    0    2G  0 part /boot     └─sda2               8:2    0   98G  0 part       ├─openeuler-root 253:0    0   92G  0 lvm  /       └─openeuler-swap 253:1    0    6G  0 lvm  [SWAP]     sdb                  8:16   0   10G  0 disk     └─vg01-lv001       253:2    0   20G  0 lvm     sdc                  8:32   0   10G  0 disk     └─vg01-lv001       253:2    0   20G  0 lvm     sdd                  8:48   0   10G  0 disk     └─vg01-lv001       253:2    0   20G  0 lvm     sr0                 11:0    1  3.5G  0 rom     [root@O-Friday mapper]# e2fsck -f /dev/mapper/vg01-lv001     e2fsck 1.46.4 (18-Aug-2021)     Pass 1: Checking inodes, blocks, and sizes     Pass 2: Checking directory structure     Pass 3: Checking directory connectivity     Pass 4: Checking reference counts     Pass 5: Checking group summary information     /dev/mapper/vg01-lv001: 11/1310720 files (0.0% non-contiguous), 126322/5242880 blocks     
15. 扩展逻辑卷大小 与14是相反操作
三种扩展方式     lvextend -l +40%FREE /dev/mapper/vg01-lv002     lvextend -l +2560 /dev/mapper/vg01-lv002     lvextend -L +10G /dev/mapper/vg01-lv002          [root@O-Friday ~]# lvextend -l +100%FREE /dev/mapper/vg01-lv001       Size of logical volume vg01/lv001 changed from 20.00 GiB (5120 extents) to <29.99 GiB (7677 extents).       Logical volume vg01/lv001 successfully resized.          此时,只是扩展了逻辑卷,分区大小并没有变化     扩展分区:     如果是ext4类型     resize2fs /dev/mapper/vg01-lv001     如果是xfs类型     xfs_growfs /dev/mapper/vg01-lv001          [root@O-Friday ~]# resize2fs /dev/mapper/vg01-lv001     resize2fs 1.46.4 (18-Aug-2021)     Please run "e2fsck -f /dev/mapper/vg01-lv001" first.          [root@O-Friday ~]# e2fsck -f /dev/mapper/vg01-lv001     e2fsck 1.46.4 (18-Aug-2021)     Pass 1: Checking inodes, blocks, and sizes     Pass 2: Checking directory structure     Pass 3: Checking directory connectivity     Pass 4: Checking reference counts     Pass 5: Checking group summary information     /dev/mapper/vg01-lv001: 11/1310720 files (0.0% non-contiguous), 126322/5242880 blocks     [root@O-Friday ~]# resize2fs /dev/mapper/vg01-lv001     resize2fs 1.46.4 (18-Aug-2021)     Resizing the filesystem on /dev/mapper/vg01-lv001 to 7861248 (4k) blocks.     The filesystem on /dev/mapper/vg01-lv001 is now 7861248 (4k) blocks long.          重新挂载分区,查看,已经是30G          [root@O-Friday ~]# mount /dev/vg01/lv001 /data     [root@O-Friday ~]# df -h     Filesystem                  Size  Used Avail Use% Mounted on     devtmpfs                    4.0M     0  4.0M   0% /dev     tmpfs                       1.7G   12K  1.7G   1% /dev/shm     tmpfs                       676M  9.2M  667M   2% /run     tmpfs                       4.0M     0  4.0M   0% /sys/fs/cgroup     /dev/mapper/openeuler-root   90G  2.5G   83G   3% /     tmpfs                       1.7G     0  1.7G   0% /tmp     /dev/sda1                   2.0G  251M  1.6G  14% /boot     /dev/mapper/vg01-lv001       30G   24K   28G   1% /data     
16. lvm中添加新磁盘
--查询新增磁盘的名称     fdisk -l           Disk /dev/sde: 10 GiB, 10737418240 bytes, 20971520 sectors     Disk model: VMware Virtual S     Units: sectors of 1 * 512 = 512 bytes     Sector size (logical/physical): 512 bytes / 512 bytes     I/O size (minimum/optimal): 512 bytes / 512 bytes          --将/dev/sde加入到vg中          [root@O-Friday ~]# vgextend vg01 /dev/sde       Physical volume "/dev/sde" successfully created.       Volume group "vg01" successfully extended          --pv中已经添加了 /dev/sde     [root@O-Friday ~]# pvdisplay       --- Physical volume ---       PV Name               /dev/sdb       VG Name               vg01       PV Size               10.00 GiB / not usable 4.00 MiB       Allocatable           yes (but full)       PE Size               4.00 MiB       Total PE              2559       Free PE               0       Allocated PE          2559       PV UUID               G3VQkg-izg2-8hNm-9bw4-Ex5r-a0ec-YBEpPr            --- Physical volume ---       PV Name               /dev/sdc       VG Name               vg01       PV Size               10.00 GiB / not usable 4.00 MiB       Allocatable           yes (but full)       PE Size               4.00 MiB       Total PE              2559       Free PE               0       Allocated PE          2559       PV UUID               16j3C2-lPOn-KdR4-R1By-NoJS-UZ8S-xj9jyy            --- Physical volume ---       PV Name               /dev/sdd       VG Name               vg01       PV Size               10.00 GiB / not usable 4.00 MiB       Allocatable           yes (but full)       PE Size               4.00 MiB       Total PE              2559       Free PE               0       Allocated PE          2559       PV UUID               YHoxPb-fDi5-P8By-dzXh-7LPz-a4BO-j6um2R            --- Physical volume ---       PV Name               /dev/sde       VG Name               vg01       PV Size               10.00 GiB / not usable 4.00 MiB       Allocatable           yes       PE Size               4.00 MiB       Total PE              2559       Free PE               2559       Allocated PE          0       PV UUID               PaMgdp-4VS7-u7Nv-m7Zg-FUPK-uTBA-yDHmkE            --- Physical volume ---       PV Name               /dev/sda2       VG Name               openeuler       PV Size               <98.00 GiB / not usable 3.00 MiB       Allocatable           yes (but full)       PE Size               4.00 MiB       Total PE              25087       Free PE               0       Allocated PE          25087       PV UUID               Yv3d0c-OjcH-8s93-MsfZ-1J          --添加后查看vg, 已有10G free空间     [root@O-Friday ~]# vgdisplay vg01       --- Volume group ---       VG Name               vg01       System ID       Format                lvm2       Metadata Areas        4       Metadata Sequence No  5       VG Access             read/write       VG Status             resizable       MAX LV                0       Cur LV                1       Open LV               0       Max PV                0       Cur PV                4       Act PV                4       VG Size               39.98 GiB       PE Size               4.00 MiB       Total PE              10236       Alloc PE / Size       7677 / <29.99 GiB       Free  PE / Size       2559 / <10.00 GiB       VG UUID               PEANLD-I1ET-hpk1-jN9V-CxZ6-ktRB-veif7v          --扩展lv,扩展所有FREE     [root@O-Friday ~]# lvextend -l +100%FREE /dev/mapper/vg01-lv001       Size of logical volume vg01/lv001 changed from <29.99 GiB (7677 extents) to 39.98 GiB (10236 extents).       Logical volume vg01/lv001 successfully resized.          --扩展分区, 需要先执行e2fsck          [root@O-Friday ~]# resize2fs /dev/mapper/vg01-lv001     resize2fs 1.46.4 (18-Aug-2021)     Please run "e2fsck -f /dev/mapper/vg01-lv001" first.          [root@O-Friday ~]# e2fsck -f /dev/mapper/vg01-lv001     e2fsck 1.46.4 (18-Aug-2021)     Pass 1: Checking inodes, blocks, and sizes     Pass 2: Checking directory structure     Pass 3: Checking directory connectivity     Pass 4: Checking reference counts     Pass 5: Checking group summary information     /dev/mapper/vg01-lv001: 11/1966080 files (0.0% non-contiguous), 167442/7861248 blocks     [root@O-Friday ~]# resize2fs /dev/mapper/vg01-lv001     resize2fs 1.46.4 (18-Aug-2021)     Resizing the filesystem on /dev/mapper/vg01-lv001 to 10481664 (4k) blocks.     The filesystem on /dev/mapper/vg01-lv001 is now 10481664 (4k) blocks long.          --重新挂载分区,查看     [root@O-Friday ~]# mount /dev/vg01/lv001 /data     [root@O-Friday ~]# df -h     Filesystem                  Size  Used Avail Use% Mounted on     devtmpfs                    4.0M     0  4.0M   0% /dev     tmpfs                       1.7G   12K  1.7G   1% /dev/shm     tmpfs                       676M  9.2M  667M   2% /run     tmpfs                       4.0M     0  4.0M   0% /sys/fs/cgroup     /dev/mapper/openeuler-root   90G  2.5G   83G   3% /     tmpfs                       1.7G     0  1.7G   0% /tmp     /dev/sda1                   2.0G  251M  1.6G  14% /boot     /dev/mapper/vg01-lv001       40G   24K   38G   1% /data     
17. /etc/fstab 在Linux系统中,`/etc/fstab`文件用于定义系统挂载文件系统的方式,包括本地磁盘、网络共享、CD-ROM等等。 每一行代表一个文件系统,每个字段用制表符分隔。以下是每个字段的含义: 1. **文件系统**: 这个字段表示要挂载的文件系统的设备名或者UUID。例如:`/dev/sda1`或`UUID=4b5324c4-2b8a-4f06-9b6c-bb5f5d5d5b9a`。也可以用LABEL来指定设备名称,例如:`LABEL=MyDisk`。注意:如果使用UUID或LABEL方式指定设备名称,则不受分区名的影响。 2. **挂载点**: 这个字段指定文件系统的挂载点,即文件系统要挂载到哪个目录下。例如:`/` 或 `/home`。 3. **文件系统类型**: 这个字段指定文件系统的类型。例如:ext4、ntfs、vfat等。如果不知道文件系统类型,可以在终端中使用 `blkid` 命令查看。 4. **选项**: 这个字段指定了文件系统的挂载选项,例如是否允许读写、是否允许执行程序、是否允许设备文件、是否自动挂载等等。多个选项之间用逗号分隔。    - `defaults`:默认选项,包括读取和写入权限、执行权限以及自动挂载。    - `ro`:只读选项,只允许读取文件系统中的内容,禁止修改。    - `noauto`:禁止自动挂载选项,文件系统不会在系统启动时自动挂载。    - `user`:允许普通用户挂载选项,通常只有超级用户才有挂载权限。    - `noexec`:禁止执行选项,防止在文件系统中执行程序和脚本文件。    - `nosuid`:禁止设置用户ID和组ID选项,防止在文件系统中执行 SUID 和 SGID 程序。    - `nodev`:禁止创建设备文件选项,防止在文件系统中创建设备文件。    - `noatime`:禁止更新访问时间选项,不更新最后一次访问时间,以提高性能。    - `nodiratime`:禁止更新目录访问时间选项,不更新目录最后一次访问时间,以提高性能。    - `relatime`:相对更新访问时间选项,只在访问时间落后于修改时间或创建时间时更新访问时间。    - `async`:异步选项,允许异步读取和写入,以提高性能。但是这样可能会导致数据丢失,因为写入操作不会立即写入磁盘。 5. **备份频率**: 这个字段指定了备份频率。在 Linux 中,`0` 表示不备份,`1` 表示每天备份一次,`2` 表示每周备份一次,`3` 表示每月备份一次。如果不需要备份,则可以将此字段设置为 0。 6. **检查顺序**: 这个字段用于指定系统引导时,需要检查哪些文件系统。默认情况下,根文件系统(/)的检查顺序为 1,其他文件系统为 2。可以将此字段设置为 0,表示不进行检查。
[root@O-Friday ~]# cat /etc/fstab          #     # /etc/fstab     # Created by anaconda on Sun Mar  5 02:52:57 2023     #     # Accessible filesystems, by reference, are maintained under "/dev/disk/".     # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info.     #     # After editing this file, run "systemctl daemon-reload" to update systemd     # units generated from this file.     #     /dev/mapper/openeuler-root /                       ext4    defaults        1 1     UUID=3ee8700a-3e9c-4c83-9336-87fa08836b84 /boot                   ext4    defaults        1 2     /dev/mapper/openeuler-swap none                    swap    defaults        0 0     

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