RH134小结（八）LVM增大和减小ext4、xfs分区
在之前 LVM分区无损增减 篇中有提到过LVM分区的无损增大和减小，不同的是，当是只是针对LVM下的ext分区的，在新版的RHEL7/centos7中默认使用的分区格式是xfs ，本篇就针对LVM下ext4和xfs分区的增大和缩小再唠叨下。
一、ext4分区下LVM的动态调整
在使用lvresize调整大小时结常需要注意与resize2fs执行的顺序。缩小空间时，一定要先执行resize2fs再执行lvresize；而增大时一定要先执行lvextend再执行resize2fs 。
1、减小大小
减小LVM分区时，一定要先umount掉挂载点再进行操作。
1[[email protected] ~]# df -H /mnt/
2Filesystem Size Used Avail Use% Mounted on
3/dev/mapper/vg-lvol0 805M 2.7M 760M 1% /mnt
4[[email protected] ~]# umount /mnt/
5[[email protected] ~]# resize2fs -f /dev/vg/lvol0 100M
6resize2fs 1.41.12 (17-May-2010)
7Resizing the filesystem on /dev/vg/lvol0 to 102400 (1k) blocks.
8The filesystem on /dev/vg/lvol0 is now 102400 blocks long.
9[[email protected] ~]# lvresize -L 100M /dev/vg/lvol0
10 WARNING: Reducing active logical volume to 100.00 MiB
11 THIS MAY DESTROY YOUR DATA (filesystem etc.)
12Do you really want to reduce lvol0? [y/n]: y
13 Size of logical volume vg/lvol0 changed from 800.00 MiB (200 extents) to 100.00 MiB (25 extents).
14 Logical volume lvol0 successfully resized
15[[email protected] ~]# mount /dev/vg/lvol0 /mnt/
16[[email protected] ~]# df -H /mnt/
17Filesystem Size Used Avail Use% Mounted on
18/dev/mapper/vg-lvol0 94M 1.6M 87M 2% /mnt
19[[email protected] ~]#
2、增大空间
1[[email protected] ~]# lvextend -L 800M /dev/vg/lvol0
2 Size of logical volume vg/lvol0 changed from 100.00 MiB (25 extents) to 800.00 MiB (200 extents).
3 Logical volume lvol0 successfully resized
4[[email protected] ~]# resize2fs -f /dev/vg/lvol0
5resize2fs 1.41.12 (17-May-2010)
6Filesystem at /dev/vg/lvol0 is mounted on /mnt; on-line resizing required
7old desc_blocks = 1, new_desc_blocks = 4
8Performing an on-line resize of /dev/vg/lvol0 to 819200 (1k) blocks.
9The filesystem on /dev/vg/lvol0 is now 819200 blocks long.
10[[email protected] ~]# df -H /mnt/
11Filesystem Size Used Avail Use% Mounted on
12/dev/mapper/vg-lvol0 805M 2.7M 761M 1% /mnt
3、一个命令搞定增大和减小
一会儿是增大，一会儿是减小，搞不好很容易搞错并造成分区损坏、数据受损，有没有不管增大减小一个命令全搞定的方法？当然有lvresize命令里有一个-r选项，该选项的作用是在执行lvresize命令的时候一并执行resize2fs ，强烈推荐该方法。
1[[email protected] ~]# df -H /mnt/
2Filesystem Size Used Avail Use% Mounted on
3/dev/mapper/vg-lvol0 805M 2.7M 761M 1% /mnt
4[[email protected] ~]# lvresize -L 300M -r /dev/vg/lvol0 -->注意此处的指定，增大时同样使用该指令
5Do you want to unmount "/mnt"? [Y|n] y
6fsck from util-linux-ng 2.17.2
7/dev/mapper/vg-lvol0: 11/203200 files (0.0% non-contiguous), 36387/819200 blocks
8resize2fs 1.41.12 (17-May-2010)
9Resizing the filesystem on /dev/mapper/vg-lvol0 to 307200 (1k) blocks.
10The filesystem on /dev/mapper/vg-lvol0 is now 307200 blocks long.
11 Size of logical volume vg/lvol0 changed from 800.00 MiB (200 extents) to 300.00 MiB (75 extents).
12 Logical volume lvol0 successfully resized
13[[email protected] ~]#
14[[email protected] ~]# df -H /mnt/
15Filesystem Size Used Avail Use% Mounted on
16/dev/mapper/vg-lvol0 297M 2.2M 279M 1% /mnt
上面已经由800M 减小到了300M，而且更神奇的是，减小前我并没有umount分区，它自动提示让我们umount掉。此处使用同样的指令增大到500M 。
1[[email protected] ~]# lvresize -L 500M -r /dev/vg/lvol0
2 Size of logical volume vg/lvol0 changed from 300.00 MiB (75 extents) to 500.00 MiB (125 extents).
3 Logical volume lvol0 successfully resized
4resize2fs 1.41.12 (17-May-2010)
5Filesystem at /dev/mapper/vg-lvol0 is mounted on /mnt; on-line resizing required
6old desc_blocks = 2, new_desc_blocks = 2
7Performing an on-line resize of /dev/mapper/vg-lvol0 to 512000 (1k) blocks.
8The filesystem on /dev/mapper/vg-lvol0 is now 512000 blocks long.
9[[email protected] ~]# df -H /mnt/
10Filesystem Size Used Avail Use% Mounted on
11/dev/mapper/vg-lvol0 500M 2.4M 472M 1% /mnt
见证到奇迹了吧，就是这么任性。
二、XFS分区
xfs分区是不支持减小操作的，这点挺蛋疼。我们先当做不知道该特性，同lvresize -r 指定试下，结果如下：
1# lvresize -L 50M /dev/vg2/xfstest -r
2Phase 1 - find and verify superblock...
3Phase 2 - using internal log
4 - scan filesystem freespace and inode maps...
5 - found root inode chunk
6Phase 3 - for each AG...
7 - scan (but don't clear) agi unlinked lists...
8 - process known inodes and perform inode discovery...
9 - agno = 0
10 - agno = 1
11 - agno = 2
12 - agno = 3
13 - agno = 4
14 - process newly discovered inodes...
15Phase 4 - check for duplicate blocks...
16 - setting up duplicate extent list...
17 - check for inodes claiming duplicate blocks...
18 - agno = 0
19 - agno = 1
20 - agno = 2
21 - agno = 3
22 - agno = 4
23No modify flag set, skipping phase 5
24Phase 6 - check inode connectivity...
25 - traversing filesystem ...
26 - traversal finished ...
27 - moving disconnected inodes to lost+found ...
28Phase 7 - verify link counts...
29No modify flag set, skipping filesystem flush and exiting.
30fsadm: Xfs filesystem shrinking is unsupported -->看到相关信息了，不好意思，xfs不支持
31 fsadm failed: 1
32 Filesystem resize failed.
增大看下：
1# df -Th /mnt
2Filesystem Type Size Used Avail Use% Mounted on
3/dev/mapper/vg2-xfstest xfs 97M 5.3M 92M 6% /mnt
4先使用lvextend增大LVM分区的大小
5# lvextend -L 120M /dev/vg2/xfstest
6 Extending logical volume vo to 120.00 MiB
7 Logical volume vo successfully resized
8再使用xfs_growfs在物理分区上调整
9# xfs_growfs /dev/vg2/xfstest
10meta-data=/dev/mapper/vg2-xfstest isize=256 agcount=5, agsize=5120 blks
11 = sectsz=512 attr=2, projid32bit=1
12 = crc=0
13data = bsize=4096 blocks=25600, imaxpct=25
14 = sunit=0 swidth=0 blks
15naming =version 2 bsize=4096 ascii-ci=0 ftype=0
16log =internal bsize=4096 blocks=853, version=2
17 = sectsz=512 sunit=0 blks, lazy-count=1
18realtime =none extsz=4096 blocks=0, rtextents=0
19data blocks changed from 25600 to 30720
20# df -Th /mnt
21Filesystem Type Size Used Avail Use% Mounted on
22/dev/mapper/vg2-xfstest xfs 117M 5.3M 92M 6% /mnt
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- Author: shisekong
- Link: https://blog.361way.com/lvm-xfs-ext4/4868.html
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