這篇文章給大家介紹Centos中Inode和Block的作用是什么,內(nèi)容非常詳細(xì),感興趣的小伙伴們可以參考借鑒,希望對(duì)大家能有所幫助。
linux 的inode及block的相關(guān)知識(shí):
1> Linux系統(tǒng)分區(qū)格式化文件系統(tǒng)之后,系統(tǒng)會(huì)分為Inode及Block兩部分:
1)Inode為系統(tǒng)文件的屬性信息(ls -l的結(jié)果)及指向文件實(shí)體的指針,但是沒有存放文件名,一般在上級(jí)目錄里的Block。
2)Block為存放數(shù)據(jù)的,ext3/ext4一般為1k,2k,4k,一般默認(rèn)4k
3)一個(gè)文件不論多大至少占用一個(gè)Inode和一個(gè)Block,一個(gè)Block只能存放一個(gè)文件的內(nèi)容,block的數(shù)量大于Inode的數(shù)量,多個(gè)文件可以占用同一個(gè) inode(硬鏈接) 。
4)訪問(wèn)文件, 通過(guò)文件-->inode(驗(yàn)證權(quán)限)--->blocks.
5)inode 一般情況默認(rèn)256B,block大小1k,2k,4k,默認(rèn)4k,注意,引導(dǎo)分區(qū)等特殊分區(qū)除外。
6)通過(guò)df -i 查看inode的數(shù)量及使用情況,dumpe2fs /dev/sda1 查看inode及block的大小和數(shù)量。
7)一個(gè)block只能 被一個(gè)文件使用 ,如果一個(gè)文件很小block太大,剩余空間浪費(fèi),無(wú)法繼續(xù)被其他文件使用。
8)block不是越大越好,根據(jù)業(yè)務(wù)的文件大小進(jìn)行選擇,一般就是默認(rèn) 4k。
9)可以在格式化的時(shí)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(lái)檢查linux服務(wù)器的文件系統(tǒng)的磁盤空間占用情況??梢岳迷撁顏?lái)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(xiàng)] [文件]
2.參數(shù) :
df -i 查看參數(shù)多少個(gè)
[root@techW ~]# df -i Filesystem Inodes IUsed IFree IUse% Mounted on /dev/mapper/vg_techw-lv_root 1152816 55846 1096970 5% / tmpfs 125596 1 125595 1% /dev/shm /dev/sda1 128016 38 127978 1% /boot
df -h 查看磁盤大?。?/p>
[root@techW ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_techw-lv_root 18G 1.5G 15G 9% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 477M 36M 416M 8% /boot
查看當(dāng)前系統(tǒng)分區(qū)的Inode及Block的總量及使用量:
[root@techW ~]# dumpe2fs /dev/sda1 | grep -i "block size" dumpe2fs 1.41.12 (17-May-2010) Block size: 1024 [root@techW ~]# [root@techW ~]# [root@techW ~]# dumpe2fs /dev/sda1 | grep -i "inode size" dumpe2fs 1.41.12 (17-May-2010) Inode size: 128 ###boot分區(qū)為128,常規(guī)分區(qū)為256 [root@techW ~]# [root@techW ~]# [root@techW ~]# dumpe2fs /dev/sda1 | grep -i "inode count" dumpe2fs 1.41.12 (17-May-2010) Inode count: 128016 [root@techW ~]# [root@techW ~]# dumpe2fs /dev/sda1 | grep -i "block count" dumpe2fs 1.41.12 (17-May-2010) Block count: 512000 Reserved block count: 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(shù)量:
1)添加一塊5G的磁盤,為方便區(qū)分設(shè)置為/dev/sdb,fdisk分區(qū),然后mkfs.ext4格式化
(虛擬機(jī)增加一塊5G的硬盤,分區(qū),格式化)
[root@techW ~]# fdisk /dev/sdb Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel Building a new DOS disklabel with disk identifier 0x2d37eabe. Changes will remain in memory only, until you decide to write them. After that, of course, the previous content won't be recoverable. Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) WARNING: DOS-compatible mode is deprecated. It's strongly recommended to switch off the mode (command 'c') and change display units to sectors (command 'u'). Command (m for help): n ### add a new partition Command action e extended p primary partition (1-4) p Partition number (1-4): 2 ### 為做區(qū)分,選擇2 First cylinder (1-652, default 1): Using default value 1 Last cylinder, +cylinders or +size{K,M,G} (1-652, default 652): Using default value 652 Command (m for help): w ### write table to disk and exit The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
分區(qū)時(shí)的參數(shù)命令:
a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition l list known partition types m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition's system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only)
[root@techW ~]# mkfs.ext4 /dev/sdb2 mke2fs 1.41.12 (17-May-2010) Filesystem label= OS type: Linux Block size=4096 (log=2) ###默認(rèn)的Block的大小為4096 Fragment size=4096 (log=2) Stride=0 blocks, Stripe width=0 blocks 327680 inodes, 1309289 blocks 65464 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=1342177280 40 block groups 32768 blocks per group, 32768 fragments per group 8192 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 26 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
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 -b 2048 -I 2048 /dev/sdb2 mke2fs 1.41.12 (17-May-2010) Filesystem label= OS type: Linux Block size=2048 (log=1) Fragment size=2048 (log=1) Stride=0 blocks, Stripe width=0 blocks 326400 inodes, 2618578 blocks 130928 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=540016640 160 block groups 16384 blocks per group, 16384 fragments per group 2040 inodes per group Superblock backups stored on blocks: 16384, 49152, 81920, 114688, 147456, 409600, 442368, 802816, 1327104, 2048000 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 30 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
4)使用dumpe2fs命令查詢Inode和Block的大?。?/p>
[root@techW ~]# dumpe2fs /dev/sdb2 | grep "Inode size" dumpe2fs 1.41.12 (17-May-2010) Inode size: 2048 ###大小更改成功 [root@techW ~]# s /dev/sdb2 | grep "Block size" dumpe2fs 1.41.12 (17-May-2010) Block size: 2048 ###大小更改成功
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