公司新購了台存儲，24塊SATA盤，每塊2T，用22塊做了兩組RAID6，剩余兩塊為熱備；兩組RAID6的物理卷放進了一個邏輯卷，由此這個邏輯卷直達32T。
OS版本：centos 6.3
# lvdisplay
--- Logical volume ---
LV Path /dev/VolGroup01/LogVol00
LV Name LogVol00
VG Name VolGroup01
LV UUID Ts6MOq-etKx-GDPU-0AHF-jIMi-pqrz-cssj7v
LV Write Access read/write
LV Creation host, time ,
LV Status available
# open 0
LV Size 32.70 TiB
Current LE 8570874
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2
以前從來沒格式化過這么大空間的卷，嘗試用ext4，做了好多遍都沒能成功；改用
xfs，終於搞定，在此記一筆。
1、修改yum配置文件，找到centosplus將enabled=0改為1
#vim /etc/yum.repos.d/CentOS-Base.repo
[centosplus]
enabled=1
2、添加xfs需要的用戶組
#useradd mockbuild
3、安裝xfs相關包，掛載xfs內核
# yum install xfsprogs kmod-xfs xfsdump xfsprogs-devel
# modprobe xfs
# lsmod |grep xfs
xfs 1042331 0
exportfs 4236 1 xfs
4、看看mkfs.xfs的參數選項
# mkfs.xfs --help
mkfs.xfs: invalid option -- '-'
unknown option --
Usage: mkfs.xfs
/* blocksize */ [-b log=n|size=num]
/* data subvol */ [-d agcount=n,agsize=n,file,name=xxx,size=num,
(sunit=value,swidth=value|su=num,sw=num),
sectlog=n|sectsize=num
/* inode size */ [-i log=n|perblock=n|size=num,maxpct=n,attr=0|1|2,
projid32bit=0|1]
/* log subvol */ [-l agnum=n,internal,size=num,logdev=xxx,version=n
sunit=value|su=num,sectlog=n|sectsize=num,
lazy-count=0|1]
/* label */ [-L label (maximum 12 characters)]
/* naming */ [-n log=n|size=num,version=2|ci]
/* prototype file */ [-p fname]
/* quiet */ [-q]
/* realtime subvol */ [-r extsize=num,size=num,rtdev=xxx]
/* sectorsize */ [-s log=n|size=num]
/* version */ [-V]
devicename
<devicename> is required unless -d name=xxx is given.
<num> is xxx (bytes), xxxs (sectors), xxxb (fs blocks), xxxk (xxx KiB),
xxxm (xxx MiB), xxxg (xxx GiB), xxxt (xxx TiB) or xxxp (xxx PiB).
<value> is xxx (512 byte blocks).
5、開始格式化
# mkfs.xfs -f -i size=512 -l size=128m,lazy-count=1 -d agcount=16 /dev/VolGroup01/LogVol00
agsize (548535936 blocks) too big, maximum is 268435455 blocks
提示agsize太大了，增大agcount到32試試
# mkfs.xfs -f -b size=16384 -i size=512 -l size=128m,lazy-count=1 -d agcount=32 /dev/VolGroup01/LogVol00
agsize (68566992 blocks) too big, maximum is 67108863 blocks
還是提示agsize太大，不過68566992 blocks已經不比maximum值大多少了，再增大agcount一倍試試
# mkfs.xfs -f -i size=512 -l size=128m,lazy-count=1 -d agcount=64 /dev/VolGroup01/LogVol00
meta-data=/dev/VolGroup01/LogVol00 isize=512 agcount=64, agsize=137133984 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=8776574976, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=32768, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
以上顯示已經格式化成功，塊大小是默認大小4K；下面mount到/data下，掛載成功！
# mount -t xfs /dev/VolGroup01/LogVol00 /data
期間嘗試過將塊大小設大一點，比如16K，格式化可以完成，但掛載時總是報錯；
# mkfs.xfs -f -b size=16384 -i size=512 -l size=128m,lazy-count=1 -d agcount=64 /dev/VolGroup01/LogVol00
meta-data=/dev/VolGroup01/LogVol00 isize=512 agcount=64, agsize=34283496 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=16384 blocks=2194143744, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=16384 ascii-ci=0
log =internal log bsize=16384 blocks=8192, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=16384 blocks=0, rtextents=0
# mount -t xfs /dev/VolGroup01/LogVol00 /data
mount: Function not implemented
# pagesize
4096
在XFS官網文檔里貌似找到了答案：
mkfs - Allocation Block Size
Specify the fundamental allocation block size of the filesystem.
The default value is 4KB, the minimum is 512 bytes, and the maximum is 64KB
XFS on Linux currently only supports pagesize or smaller blocks.
To create a filesystem with a block size of 2048 bytes you would use:
mkfs.xfs -b size=2048 device
Smaller block sizes reduce wasted space for lots of small files.
就是說格式化的時候塊大小要小於等於操作系統pagesize