本經驗均在CentOSrelease6.7(Final)下操作,如知識有欠缺之處 歡迎批評指正。
linux 的inode及block的相關知識:
1> Linux系統分區格式化文件系統之後,系統會分為Inode及Block兩部分:
1)Inode為系統文件的屬性信息(ls -l的結果)及指向文件實體的指針,但是沒有存放文件名,一般在上級目錄裡的Block。
2)Block為存放數據的,ext3/ext4一般為1k,2k,4k,一般默認4k
3)一個文件不論多大至少占用一個Inode和一個Block,一個Block只能存放一個文件的內容,block的數量大於Inode的數量,多個文件可以占用同一個 inode(硬鏈接) 。
4)訪問文件, 通過文件-->inode(驗證權限)--->blocks.
5)inode 一般情況默認256B,block大小1k,2k,4k,默認4k,注意,引導分區等特殊分區除外。
6)通過df -i 查看inode的數量及使用情況,dumpe2fs /dev/sda1 查看inode及block的大小和數量。
7)一個block只能 被一個文件使用 ,如果一個文件很小block太大,剩余空間浪費,無法繼續被其他文件使用。
8)block不是越大越好,根據業務的文件大小進行選擇,一般就是默認 4k。
9)可以在格式化的時候改變inode及block的大小,使用mkfs.ext4 -b 2048 -I 1024 /dev/sdb2
2>Linux中df命令的功能是用來檢查linux服務器的文件系統的磁盤空間占用情況。可以利用該命令來獲取硬盤被占用了多少空間,目前還剩下多少空間等信息。
1.命令格式:
df [選項] [文件]
2.參數 :
df -i 查看參數多少 個
[root@techW~]
#df-i
FilesystemInodesIUsedIFreeIUse%Mountedon
/dev/mapper/vg_techw-lv_root
11528165584610969705%/
tmpfs12559611255951%
/dev/shm
/dev/sda1
128016381279781%
/boot
df -h 查看磁盤大小:
[root@techW~]
#df-h
FilesystemSizeUsedAvailUse%Mountedon
/dev/mapper/vg_techw-lv_root
18G1.5G15G9%/
tmpfs491M0491M0%
/dev/shm
/dev/sda1
477M36M416M8%
/boot
查看當前系統分區的Inode及Block的總量及使用量:
[root@techW~]
#dumpe2fs/dev/sda1|grep-i"blocksize"
dumpe2fs1.41.12(17-May-2010)
Blocksize:1024
[root@techW~]
#
[root@techW~]
#
[root@techW~]
#dumpe2fs/dev/sda1|grep-i"inodesize"
dumpe2fs1.41.12(17-May-2010)
Inodesize:128
###boot分區為128,常規分區為256
[root@techW~]
#
[root@techW~]
#
[root@techW~]
#dumpe2fs/dev/sda1|grep-i"inodecount"
dumpe2fs1.41.12(17-May-2010)
Inodecount:128016
[root@techW~]
#
[root@techW~]
#dumpe2fs/dev/sda1|grep-i"blockcount"
dumpe2fs1.41.12(17-May-2010)
Blockcount:512000
Reservedblockcount:25600
3>添加一塊磁盤,格式化,改變Inode及 Block的大小,掛載查看硬盤的Inode及Block數量:
1)添加一塊5G的磁盤,為方便區分設置為/dev/sdb,fdisk分區,然後mkfs.ext4格式化
(虛擬機增加一塊5G的硬盤,分區,格式化)
[root@techW~]
#fdisk/dev/sdb
DevicecontainsneitheravalidDOSpartitiontable,norSun,SGIorOSFdisklabel
BuildinganewDOSdisklabelwithdiskidentifier0x2d37eabe.
Changeswillremain
in
memoryonly,
until
youdecidetowritethem.
Afterthat,ofcourse,thepreviouscontentwon'tberecoverable.
Warning:invalidflag0x0000ofpartitiontable4willbecorrectedbyw(rite)
WARNING:DOS-compatiblemodeisdeprecated.It'sstronglyrecommendedto
switchoffthemode(
command
'c'
)andchangedisplay
units
to
sectors(
command
'u'
).
Command(m
for
help):n
###addanewpartition
Commandaction
eextended
pprimarypartition(1-4)
p
Partitionnumber(1-4):2
###為做區分,選擇2
Firstcylinder(1-652,default1):
Usingdefaultvalue1
Lastcylinder,+cylindersor+size{K,M,G}(1-652,default652):
Usingdefaultvalue652
Command(m
for
help):w
###writetabletodiskandexit
Thepartitiontablehasbeenaltered!
Callingioctl()tore-
read
partitiontable.
Syncingdisks.
分區時的參數命令:
atoggleabootableflag
beditbsddisklabel
ctogglethedoscompatibilityflag
ddeleteapartition
llistknownpartitiontypes
mprintthismenu
naddanewpartition
ocreateanewemptyDOSpartitiontable
pprintthepartitiontable
qquitwithoutsavingchanges
screateanewemptySundisklabel
tchangeapartition'ssystem
id
uchangedisplay
/entry
units
v
verifythepartitiontable
wwritetabletodiskand
exit
xextrafunctionality(expertsonly)
[root@techW~]
#mkfs.ext4/dev/sdb2
mke2fs1.41.12(17-May-2010)
Filesystemlabel=
OS
type
:Linux
Blocksize=4096(log=2)
###默認的Block的大小為4096
Fragmentsize=4096(log=2)
Stride=0blocks,Stripewidth=0blocks
327680inodes,1309289blocks
65464blocks(5.00%)reserved
for
thesuperuser
Firstdatablock=0
Maximumfilesystemblocks=1342177280
40block
groups
32768blockspergroup,32768fragmentspergroup
8192inodespergroup
Superblockbackupsstoredonblocks:
32768,98304,163840,229376,294912,819200,884736
Writinginodetables:
done
Creatingjournal(32768blocks):
done
Writingsuperblocksandfilesystemaccountinginformation:
done
Thisfilesystemwillbeautomaticallycheckedevery26mountsor
180days,whichevercomesfirst.Usetune2fs-cor-itooverride.
2)###inode的大小范圍為128-2048,block的大小范圍為1024-4096####
3)將Block和Inode的大小都改為2048:
[root@techW~]
#mkfs.ext4-b2048-I2048/dev/sdb2
mke2fs1.41.12(17-May-2010)
Filesystemlabel=
OS
type
:Linux
Blocksize=2048(log=1)
Fragmentsize=2048(log=1)
Stride=0blocks,Stripewidth=0blocks
326400inodes,2618578blocks
130928blocks(5.00%)reserved
for
thesuperuser
Firstdatablock=0
Maximumfilesystemblocks=540016640
160block
groups
16384blockspergroup,16384fragmentspergroup
2040inodespergroup
Superblockbackupsstoredonblocks:
16384,49152,81920,114688,147456,409600,442368,802816,1327104,
2048000
Writinginodetables:
done
Creatingjournal(32768blocks):
done
Writingsuperblocksandfilesystemaccountinginformation:
done
Thisfilesystemwillbeautomaticallycheckedevery30mountsor
180days,whichevercomesfirst.Usetune2fs-cor-itooverride.
4)使用dumpe2fs命令查詢Inode和Block的大小:
[root@techW~]
#dumpe2fs/dev/sdb2|grep"Inodesize"
dumpe2fs1.41.12(17-May-2010)
Inodesize:2048
###大小更改成功
[root@techW~]
#
s
/dev/sdb2
|
grep
"Blocksize"
dumpe2fs1.41.12(17-May-2010)
Blocksize:2048
###大小更改成功
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