系统运输
thisissecondpartofunderstandingunix/Linux文件系统，partiishere.letustakeanexampleof 20gb hard disk.theentirediskspacesube
UNIX/Linux文件系统块
theblocksusedfortwodifferentpurpose :
mostblocksstoresuserdataakafiles (用户数据)。
someblocksineveryfilesystemstorethefilesystem\\ s metadata.sowhatthehellisametadata？
insimplewordsmetadatadescribesthestructureofthefilesystem.mostcommonmetadatastructurearesuperblock，inodeanddirectories.fories
超级拦网
eachfilesystemisdifferentandtheyhavetypelikeext 2，ext3 etc.furthereachfilesystemhassizelike 5gb， 10gbandstatussuchasmountstatus.inshorteachfilesystemhasasuperblock，whichcontainsinformationaboutfilesystemsuchas :
文件系统类型
大小
状态
信息性boutothermetadatastructures
If this information lost，youareintrouble (数据丢失) )。 olinuxmaintainsmultipleredundantcopiesofthesuperblockineveryfilesystem.thisisveryimportantinmanyemergencysituation、 forexampleyoucanusebackupcopiestorestoredamagedprimarysuperblock.followingcommanddisplaysprimaryandbackupsuperblocklocationonocation
# dumpe2fs/dev/sda1| grep-isuperblock
Output :
主super block at 0，Group descriptors at 1-7
Backup superblock at 32768，Group descriptors at 32769-32775
Backup superblock at 98304，Group descriptors at 98305-98311
Backup superblock at 163840，groupdescriptorsat 163841-163847
Backup superblock at 229376，groupdescriptorsat 229377-229383
Backup superblock at 294912，groupdescriptorsat 294913-294919
Backup superblock at 819200，groupdescriptorsat 819201-819207
Backup superblock at 884736，groupdescriptorsat 884737-884743
Backup superblock at 1605632、groupdescriptorsat 1605633-1605639
Backup superblock at 2654208、groupdescriptorsat 2654209-2654215
Backup superblock at 4096000，groupdescriptorsat 4096001-4096007
Backup superblock at 7962624，groupdescriptorsat 7962625-7962631
Backup superblock at 11239424，groupdescriptorsat 11239425-11239431
Backup superblock at 20480000、groupdescriptorsat 20480001-20480007
Backup superblock at 23887872、groupdescriptorsat 23887873-23887879
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