xfs lv 縮小

1. 查看 v7 的檔案系統，家目錄 /home 的分割區為 xfs。
   

   [root@kvm7 ~]# df -Th /home
   Filesystem                 Type  Size  Used Avail Use% Mounted on
   /dev/mapper/vg_kvm7home-vo xfs    97M  5.3M   92M   6% /home
   

2. 先卸載家目錄 /home，家目錄忙錄中無法卸載。
   

   [root@kvm7 ~]# umount /home
   umount: /home: target is busy.
           (In some cases useful info about processes that use
            the device is found by lsof(8) or fuser(1))
   

3. 使用 lsof 查看家目錄 /home 使用狀況，為自動掛載程式掛載在 /home/guests。
   

   [root@kvm7 ~]# lsof | grep /home
   automount 1539         root   16r      DIR               0,37         0      18663 /home/guests
   automount 1539 1540    root   16r      DIR               0,37         0      18663 /home/guests
   automount 1539 1541    root   16r      DIR               0,37         0      18663 /home/guests
   automount 1539 2032    root   16r      DIR               0,37         0      18663 /home/guests
   automount 1539 2068    root   16r      DIR               0,37         0      18663 /home/guests
   automount 1539 2096    root   16r      DIR               0,37         0      18663 /home/guests
   

4. 先關閉自動掛載，再卸載家目錄 /home。
   

   [root@kvm7 ~]# systemctl stop autofs.service 
   [root@kvm7 ~]# umount /home
   

5. 使用 lvresize 將 /dev/vg_kvm7home/vo 由 100M 縮小為 50M，出現 Xfs 檔案系統不支援縮小的訊息，表示 lvm 中 xfs 檔案系統格式的 lv 無法直接縮小，若真有必要縮小，必須建一個新的較小的 lv，將資料移過去後再刪除目前的 lv。
   

   [root@kvm7 ~]# lvresize -L 50M /dev/vg_kvm7home/vo -r
   Phase 1 - find and verify superblock...
   Phase 2 - using internal log
           - scan filesystem freespace and inode maps...
           - found root inode chunk
   Phase 3 - for each AG...
           - scan (but don't clear) agi unlinked lists...
           - process known inodes and perform inode discovery...
           - agno = 0
           - agno = 1
           - agno = 2
           - agno = 3
           - agno = 4
           - process newly discovered inodes...
   Phase 4 - check for duplicate blocks...
           - setting up duplicate extent list...
           - check for inodes claiming duplicate blocks...
           - agno = 0
           - agno = 1
           - agno = 2
           - agno = 3
           - agno = 4
   No modify flag set, skipping phase 5
   Phase 6 - check inode connectivity...
           - traversing filesystem ...
           - traversal finished ...
           - moving disconnected inodes to lost+found ...
   Phase 7 - verify link counts...
   No modify flag set, skipping filesystem flush and exiting.
   fsadm: Xfs filesystem shrinking is unsupported
     fsadm failed: 1
     Filesystem resize failed.