引用http://blog.chinaunix.net/uid-522675-id-4665059.html xfs文件系统使用总结
1.3 xfs相关常用命令
xfs_admin: 调整 xfs 文件系统的各种参数
xfs_copy: 拷贝 xfs 文件系统的内容到一个或多个目标系统（并行方式）
xfs_db: 调试或检测 xfs 文件系统（查看文件系统碎片等）
xfs_check: 检测 xfs 文件系统的完整性
xfs_bmap: 查看一个文件的块映射
xfs_repair: 尝试修复受损的 xfs 文件系统
xfs_fsr: 碎片整理
xfs_quota: 管理 xfs 文件系统的磁盘配额
xfs_metadump: 将 xfs 文件系统的元数据 (metadata) 拷贝到一个文件中
xfs_mdrestore: 从一个文件中将元数据 (metadata) 恢复到 xfs 文件系统
xfs_growfs: 调整一个 xfs 文件系统大小（只能扩展）
xfs_freeze 暂停（-f）和恢复（-u）xfs 文件系统
xfs_logprint: 打印xfs文件系统的日志
xfs_mkfile: 创建xfs文件系统
xfs_info: 查询文件系统详细信息
xfs_ncheck: generate pathnames from i-numbers for XFS
xfs_rtcp: XFS实时拷贝命令
xfs_io: 调试xfs I/O路径
2.2 计算块使用
We want to use mysql on /dev/sda3, but how can we ensure that it is aligned with the RAID stripes? It takes a small amount of math:
Start with your RAID stripe size. Let’s use 64k which is a common default. In this case 64K = 2^16 = 65536 bytes. 默认尺寸是64K
Get your sector size from fdisk. In this case 512 bytes. 扇区大小512b
Calculate how many sectors fit in a RAID stripe. 65536 / 512 = 128 sectors per stripe. 每个条带大小128个扇区。
Get start boundary of our mysql partition from fdisk: 27344896. 查看mysql分区的起始数为27344896
See if the Start boundary for our mysql partition falls on a stripe boundary by dividing the start sector of the partition by the sectors per stripe: 27344896 / 128 = 213632. This is a whole number, so we are good. If it had a remainder, then our partition would not start on a RAID stripe boundary. 查看如果由起始扇区划分的起始边界落到条带的边界，再计算扇区数，得到一个整数。如果有余数，那么我们的分区不会从raid条带边界开始。
Create the Filesystem
XFS requires a little massaging (or a lot). For a standard server, it’s fairly simple. We need to know two things:
RAID stripe size
Number of unique, utilized disks in the RAID. This turns out to be the same as the size formulas I gave above:
RAID 1+0: is a set of mirrored drives, so the number here is num drives / 2.
RAID 5: is striped drives plus one full drive of parity, so the number here is num drives – 1.
In our case, it is RAID 1+0 64k stripe with 8 drives. Since those drives each have a mirror, there are really 4 sets of unique drives that are striped over the top. Using these numbers, we set the ‘su’ and ‘sw’ options in mkfs.xfs with those two values respectively.
2.3 格式化文件系统
通过以上实例总结执行命令 mkfs.xfs -d su=64k,sw=4 /dev/sda3
3. xfs文件系统的创建
3.1 默认方法
#mkfs.xfs /dev/sdc1
meta-data=/dev/sdc1 isize=256 agcount=18, agsize=1048576 blks
data = bsize=4096 blocks=17921788, imaxpct=25
= sunit=0 swidth=0 blks, unwritten=0
naming =version 2 bsize=4096
log =internal log bsize=4096 blocks=2187, version=1
= sunit=0 blks
realtime =none extsz=65536 blocks=0, rtextents=0
3.2 指定块和内部log大小
# mkfs.xfs -b size=1k -l size=10m /dev/sdc1
meta-data=/dev/sdc1 isize=256 agcount=18, agsize=4194304 blks
data = bsize=1024 blocks=71687152, imaxpct=25
= sunit=0 swidth=0 blks, unwritten=0
naming =version 2 bsize=4096
log =internal log bsize=1024 blocks=10240, version=1
= sunit=0 blks
realtime =none extsz=65536 blocks=0, rtextents=0
3.3 使用逻辑卷做为外部日志的卷
# mkfs.xfs -l logdev=/dev/sdh,size=65536b /dev/sdc1
meta-data=/dev/sdc1 isize=256 agcount=4, agsize=76433916
blks
= sectsz=512 attr=2
data = bsize=4096 blocks=305735663,
imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =/dev/sdh bsize=4096 blocks=65536, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
3.3 目录块
# mkfs.xfs -b size=2k -n size=4k /dev/sdc1
meta-data=/dev/sdc1 isize=256 agcount=4,
agsize=152867832 blks
= sectsz=512 attr=2
data = bsize=2048 blocks=611471327,
imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=2048 blocks=298569, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
3.4 扩展文件系统
新增的空间不会使原有文件系统上的文件不会被改动，而且被增加的空间变成可用的附加的文件存储
XVM支持xfs系统的扩展
# xfs_growfs /mnt
meta-data=/mnt isize=256 agcount=30, agsize=262144 blks
data = bsize=4096 blocks=7680000, imaxpct=25
= sunit=0 swidth=0 blks, unwritten=0
naming =version 2 bsize=4096
log =internal bsize=4096 blocks=1200 version=1
= sunit=0 blks
realtime =none extsz=65536 blocks=0, rtextents=0
data blocks changed from 7680000 to 17921788
4. 文件系统的维护
4.1 碎片的整理
查看文件块状况: xfs_bmap -v file.tar.bz2
查看磁盘碎片状况: xfs_db -c frag -r /dev/sda1
整理碎片: xfs_fsr /dev/sda1
mountpoint与device要区别
挂载点
[[email protected] ~]# xfs_info /root
meta-data=/dev/mapper/centos-root isize=256 agcount=4, agsize=3110656 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=12442624, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal bsize=4096 blocks=6075, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
设备名，（下面输出比较多）
[[email protected] ~]# xfs_logprint /dev/mapper/centos-root|more
[[email protected] ~]# xfs_bmap /var/log/messages
/var/log/messages:
0: [0..119]: 6304..6423
1: [120..127]: 6440..6447
2: [128..135]: 6464..6471
[[email protected] ~]# xfs_bmap /var/log/secure
/var/log/secure:
0: [0..7]: 6424..6431
1: [8..15]: 6456..6463
2: [16..23]: 6592..6599
[[email protected] ~]# xfs_bmap -v /var/log/messages
/var/log/messages:
EXT: FILE-OFFSET BLOCK-RANGE AG AG-OFFSET TOTAL
0: [0..119]: 6304..6423 0 (6304..6423) 120
1: [120..127]: 6440..6447 0 (6440..6447) 8
2: [128..135]: 6464..6471 0 (6464..6471) 8
[[email protected] ~]# xfs_db -c frag -r /dev/xvda1
actual 326, ideal 324, fragmentation factor 0.61%
[[email protected] ~]# xfs_db -c frag -r /dev/xvda2
xfs_db: /dev/xvda2 is not a valid XFS filesystem (unexpected SB magic number 0x00000000)
Use -F to force a read attempt.
因为/dev/xvda2是一个pv,它没有包含文件系统
[[email protected] ~]# xfs_db -c frag -r /dev/mapper/centos-root
actual 20226, ideal 20092, fragmentation factor 0.66%
[root[email protected] ~]# xfs_db -c frag -r /dev/centos/root
actual 20239, ideal 20103, fragmentation factor 0.67%
[[email protected] ~]# xfs_db -c frag -r /dev/dm-0
actual 20239, ideal 20103, fragmentation factor 0.67%