XFS檔案系統是矽谷圖形公司(Silicon Graphics Inc,簡稱SGI)開發的用於IRIX(一個UNIX作業系統)的檔案系統，後將XFS移植到 作業系統上。XFS是高階日誌檔案系統，其特點極具伸縮性，同時也很健壯。2000年5月XFS透過GNU通用公共許可證移植到 Linux系統 上，透過十多年的不斷修改已經成為一款非常成熟的檔案系統。在多項針對XFS的效能測試上，XFS都取得了不俗的成績，高併發環境下甚至已經超過ext4。

一、XFS檔案系統的備份與恢復

XFS檔案系統提供了整個分割槽備份的工具xfsdump供使用者使用，使用者可以在不借助第三方軟體的情況下對XFS檔案系統上的資料實施備份。

建立XFS分割槽及測試檔案

[root@localhost ~]# ls /dev/sd*

/dev/sda /dev/sda1 /dev/sda2 /dev/sdb

[root@localhost ~]# fdisk /dev/sdb

Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.

Be careful before using the write command.

Command (m for help): p

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0x08a5199d

Device Boot Start End Blocks Id System

Command (m for help): n

Partition type:

p primary (0 primary, 0 extended, 4 free)

e extended

Select (default p): p

First sector (2048-41943039, default 2048):

Using default value 2048

Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +1G

Partition 1 of type Linux and of size 1 GiB is set

Command (m for help): p

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0x08a5199d

Device Boot Start End Blocks Id System

/dev/sdb1 2048 2099199 1048576 83 Linux

Command (m for help): w

The partition table has been altered!

Calling ioctl() to re-read partition table.

Syncing disks.

[root@localhost ~]# partprobe

Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0 has been opened read-only.

[root@localhost ~]# ls /dev/sd*

/dev/sda /dev/sda1 /dev/sda2 /dev/sdb /dev/sdb1

[root@localhost ~]# mkfs.xfs -f /dev/sdb1

meta-data=/dev/sdb1 isize=512 agcount=4, agsize=65536 blks

= sectsz=512 attr=2, projid32bit=1

= crc=1 finobt=0, sparse=0

data = bsize=4096 blocks=262144, imaxpct=25

= sunit=0 swidth=0 blks

naming =version 2 bsize=4096 ascii-ci=0 ftype=1

log =internal log bsize=4096 blocks=2560, version=2

= sectsz=512 sunit=0 blks, lazy-count=1

realtime =none extsz=4096 blocks=0, rtextents=0

[root@localhost ~]# blkid /dev/sdb1

/dev/sdb1: UUID="61a5e59d-92d3-458d-ac09-7d945469cda6" TYPE="xfs"

[root@localhost ~]# mkdir /file

[root@localhost ~]# echo "/dev/sdb1 /file xfs defaults 0 0" >> /etc/fstab

[root@localhost ~]# mount -a

[root@localhost ~]# df -h

Filesystem Size Used Avail Use% Mounted on

/dev/mapper/rhel-root 17G 1.9G 16G 12% /

devtmpfs 901M 0 901M 0% /dev

tmpfs 912M 0 912M 0% /dev/shm

tmpfs 912M 8.7M 903M 1% /run

tmpfs 912M 0 912M 0% /sys/fs/cgroup

/dev/sr0 3.8G 3.8G 0 100% /yum

/dev/sda1 1014M 143M 872M 15% /boot

tmpfs 183M 0 183M 0% /run/user/0

/dev/sdb1 1014M 33M 982M 4% /file

[root@localhost ~]# cd /file/

[root@localhost file]# ls

[root@localhost file]# touch file{1..100}

[root@localhost file]# ls

file1 file16 file23 file30 file38 file45 file52 file6 file67 file74 file81 file89 file96

file10 file17 file24 file31 file39 file46 file53 file60 file68 file75 file82 file9 file97

file100 file18 file25 file32 file4 file47 file54 file61 file69 file76 file83 file90 file98

file11 file19 file26 file33 file40 file48 file55 file62 file7 file77 file84 file91 file99

file12 file2 file27 file34 file41 file49 file56 file63 file70 file78 file85 file92

file13 file20 file28 file35 file42 file5 file57 file64 file71 file79 file86 file93

file14 file21 file29 file36 file43 file50 file58 file65 file72 file8 file87 file94

file15 file22 file3 file37 file44 file51 file59 file66 file73 file80 file88 file95

備份XFS分割槽

[root@localhost file]# mkdir /backup

[root@localhost file]# yum install -y xfsdump

[root@localhost file]# xfsdump -f /backup/file.bak /file

# 利用 xfsdump 備份掛載點 /file 對應的分割槽

xfsdump: using file dump (drive_simple) strategy

xfsdump: version 3.1.4 (dump format 3.0) - type ^C for status and control

============================= dump label dialog ==============================

# 輸入 dump 會話標籤

please enter label for this dump session (timeout in 300 sec)

-> file.bak

session label entered: "file.bak"

--------------------------------- end dialog ---------------------------------

xfsdump: level 0 dump of localhost.localdomain:/file

xfsdump: dump date: Thu Oct 31 22:16:02 2019

xfsdump: session id: 02a1445f-5ff3-4518-ab2c-888d9e2a4c44

xfsdump: session label: "file.bak"

xfsdump: ino map phase 1: constructing initial dump list

xfsdump: ino map phase 2: skipping (no pruning necessary)

xfsdump: ino map phase 3: skipping (only one dump stream)

xfsdump: ino map construction complete

xfsdump: estimated dump size: 52800 bytes

============================= media label dialog =============================

# 輸入媒體標籤

please enter label for media in drive 0 (timeout in 300 sec)

-> file

media label entered: "file"

--------------------------------- end dialog ---------------------------------

xfsdump: creating dump session media file 0 (media 0, file 0)

xfsdump: dumping ino map

xfsdump: dumping directories

xfsdump: dumping non-directory files

xfsdump: ending media file

xfsdump: media file size 86544 bytes

xfsdump: dump size (non-dir files) : 0 bytes

xfsdump: dump complete: 27 seconds elapsed

xfsdump: Dump Summary:

xfsdump: stream 0 /backup/file.bak OK (success)

xfsdump: Dump Status: SUCCESS

[root@localhost file]# ls /backup/

# 已經成功建立備份檔案

file.bak

恢復過程