linux btrfs文件系統(tǒng)及管理
什么是btrfs?
Btrfs(B-tree文件系統(tǒng),通常念成Butter FS,Better FS或B-tree FS),linux文件系統(tǒng),具有寫時(shí)復(fù)制COW(copy-on-write),改善ext3文件系統(tǒng)單文件大小限制,并加入其他特性,如可寫快照,快照的快照,內(nèi)建RAID,子卷(subvloume),專注于容錯(cuò),修復(fù)和易于管理。單文件可達(dá)16EB,最大文件數(shù)量2^64,最大卷容量16EB,等。
btrfs功能特性
1,COW:寫時(shí)復(fù)制,每次寫入數(shù)據(jù)時(shí),先將數(shù)據(jù)寫入到新的block,寫入成功后,更改舊數(shù)據(jù)塊指針到新數(shù)據(jù)塊,而非更改本身。
2,多物理卷支持,btrfs內(nèi)建raid,可在線增刪磁盤設(shè)備,可在線擴(kuò)展和縮減磁盤空間。
3,數(shù)據(jù)和元數(shù)據(jù)校驗(yàn)碼,checksum
4,子卷,可單獨(dú)掛載子卷
5,可寫快照,快照的快照,單個(gè)文件快照。
6,透明壓縮
7,ext3/4和btrfs無痛互轉(zhuǎn)
btrfs 基本用法:
- [root@localhost~]#btrfs--help#查看幫助可以看到btrfs有很多子命令,用法也很多,這里只舉例常用選項(xiàng)。
- usage:btrfs[--help][--version]<group>[<group>...]<command>[<args>]
- btrfssubvolumecreate[-i<qgroupid>][<dest>/]<name>#創(chuàng)建子卷
- Createasubvolume
- btrfssubvolumedelete[options]<subvolume>[<subvolume>...]#刪除子卷
- Deletesubvolume(s)
- btrfssubvolumelist[options][-G[+|-]value][-C[+|-]value][--sort=gen,ogen,rootid,path]<path>#顯示子卷列表
- Listsubvolumes(andsnapshots)
- btrfssubvolumesnapshot[-r][-i<qgroupid>]<source><dest>|[<dest>/]<name>#創(chuàng)建子卷快照
- Createasnapshotofthesubvolume
- btrfssubvolumeget-default<path>#獲取子卷默認(rèn)的文件系統(tǒng)
- Getthedefaultsubvolumeofafilesystem
- btrfssubvolumeset-default<subvolid><path>#設(shè)置默認(rèn)系統(tǒng)給子卷
- Setthedefaultsubvolumeofafilesystem
- btrfssubvolumefind-new<path><lastgen>#列出btrfs文件系統(tǒng)中最近修改的文件,結(jié)合find命令
- Listtherecentlymodifiedfilesinafilesystem
- btrfssubvolumeshow<subvol-path>#顯示更多的子卷信息
- Showmoreinformationofthesubvolume
- btrfssubvolumesync<path>[<subvol-id>...]#子卷同步,類似mount同步模式,內(nèi)存數(shù)據(jù)同步到磁盤,有待查證。
- Waituntilgivensubvolume(s)arecompletelyremovedfromthefilesystem.
- btrfsfilesystemdf[options]<path>#顯示掛載的文件系統(tǒng)詳細(xì)信息。
- Showspaceusageinformationforamountpoint
- btrfsfilesystemshow[options][<path>|<uuid>|<device>|label]#顯示創(chuàng)建文件系統(tǒng)的磁盤信息。
- Showthestructureofafilesystem
- btrfsfilesystemsync<path>#強(qiáng)制文件系統(tǒng)同步,
- Forceasynconafilesystem
- btrfsfilesystemdefragment[options]<file>|<dir>[<file>|<dir>...]#碎片整理
- Defragmentafileoradirectory
- btrfsfilesystemresize[devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max<path>#btrfs文件系統(tǒng)在線擴(kuò)展和縮減空間
- Resizeafilesystem
- btrfsfilesystemlabel[<device>|<mount_point>][<newlabel>]#改變btrfs文件系統(tǒng)卷標(biāo)
- Getorchangethelabelofafilesystem
- btrfsfilesystemusage[options]<path>[<path>..]#顯示文件系統(tǒng)當(dāng)前的使用信息。
- Showdetailedinformationaboutinternalfilesystemusage.
- btrfsbalancestart[options]<path>#改變磁盤chunk,在線改數(shù)據(jù)和元數(shù)據(jù)存儲(chǔ)方式,單盤改raid,前提滿足raid要求。
- Balancechunksacrossthedevices
- btrfsbalancepause<path>#暫停chunk更改,數(shù)據(jù)量較大,轉(zhuǎn)換時(shí)間較長時(shí),先暫停。
- Pauserunningbalance
- btrfsbalancecancel<path>#取消chunk更改,如上
- Cancelrunningorpausedbalance
- btrfsbalanceresume<path>#中斷balance的操作,如上
- Resumeinterruptedbalance
- btrfsbalancestatus[-v]<path>#顯示balance操作狀態(tài)如上
- Showstatusofrunningorpausedbalance
- btrfsdeviceadd[options]<device>[<device>...]<path>#文件系統(tǒng)增加磁盤
- Addadevicetoafilesystem
- btrfsdevicedelete<device>[<device>...]<path>#文件系統(tǒng)刪除磁盤
- Removeadevicefromafilesystem
- btrfsdevicescan[(-d|--all-devices)|<device>[<device>...]]#文件系統(tǒng)磁盤掃描
- Scandevicesforabtrfsfilesystem
- btrfsdeviceready<device>#猜測是檢測加入的設(shè)備有沒有被掛載
- Checkdevicetoseeifithasallofitsdevicesincacheformounting
- btrfsdevicestats[-z]<path>|<device>#顯示文件系統(tǒng)的設(shè)備狀態(tài)
- ShowcurrentdeviceIOstats.-ztoresetstatsafterwards.
- btrfsdeviceusage[options]<path>[<path>..]#顯示文件系統(tǒng)內(nèi)部設(shè)備詳細(xì)使用信息
- Showdetailedinformationaboutinternalallocationsindevices.
btrfs文件系統(tǒng)管理
為分區(qū)創(chuàng)建btrfs文件系統(tǒng)
- [root@localhost~]#fdisk-l|grep"^Disk/dev/sd[a-z]"#準(zhǔn)備sd{b,c,d,e}4塊20G磁盤,未做任何分區(qū)。
- Disk/dev/sda:107.4GB,107374182400bytes,209715200sectors
- Disk/dev/sdb:21.5GB,21474836480bytes,41943040sectors
- Disk/dev/sdc:21.5GB,21474836480bytes,41943040sectors
- Disk/dev/sde:21.5GB,21474836480bytes,41943040sectors
- Disk/dev/sdd:21.5GB,21474836480bytes,41943040sectors
創(chuàng)建單分區(qū)btrfs并查看
- [root@localhost~]#mkfs.btrfs-L'btrfs'/dev/sdb
- btrfs-progsv3.19.1
- Seehttp://btrfs.wiki.kernel.orgformoreinformation.
- TurningONincompatfeature'extref':increasedhardlinklimitperfileto65536
- TurningONincompatfeature'skinny-metadata':reduced-sizemetadataextentrefs
- fscreatedlabelbtrfson/dev/sdb
- nodesize16384leafsize16384sectorsize4096size20.00GiB
- [root@localhost~]#btrfsfilesystemshow
- Label:'btrfs'uuid:2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Totaldevices1FSbytesused112.00KiB
- devid1size20.00GiBused2.04GiBpath/dev/sdb
- btrfs-progsv3.19.1
- [root@localhost~]#mount-ocompress=lzo-Lbtrfs/btrfs/掛載時(shí)可以設(shè)定透明壓縮機(jī)制。
- [root@localhost~]#btrfsfilesystemdf/btrfs
- Data,single:total=8.00MiB,used=256.00KiB
- System,DUP:total=8.00MiB,used=16.00KiB
- System,single:total=4.00MiB,used=0.00B
- Metadata,DUP:total=1.00GiB,used=112.00KiB
- Metadata,single:total=8.00MiB,used=0.00B
- GlobalReserve,single:total=16.00MiB,used=0.00B
再添加一塊磁盤
- [root@localhost~]#btrfsdeviceadd/dev/sdc/btrfs#添加磁盤,刪除用btrfsdevicedelete/dev/sdc/btrfs
- [root@localhost~]#btrfsfish
- Label:'btrfs'uuid:2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Totaldevices2FSbytesused384.00KiB
- devid1size20.00GiBused2.04GiBpath/dev/sdb
- devid2size20.00GiBused0.00Bpath/dev/sdc
- btrfs-progsv3.19.1
- [root@localhost~]#
在線增加或縮減空間,在線改變空間,可以讓lvm坐冷板凳了。
- [root@localhost~]#btrfsfiresize-10G/btrfs/#在線縮減空間
- Resize'/btrfs/'of'-10G'
- [root@localhost~]#btrfsfish
- Label:'btrfs'uuid:2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Totaldevices2FSbytesused384.00KiB
- devid1size10.00GiBused2.04GiBpath/dev/sdb
- devid2size20.00GiBused0.00Bpath/dev/sdc
- btrfs-progsv3.19.1
- [root@localhost~]#btrfsfiresize+7G/btrfs/#在線增加空間
- Resize'/btrfs/'of'+7G'
- [root@localhost~]#btrfsfish
- Label:'btrfs'uuid:2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Totaldevices2FSbytesused384.00KiB
- devid1size17.00GiBused2.04GiBpath/dev/sdb
- devid2size20.00GiBused0.00Bpath/dev/sdc
- btrfs-progsv3.19.1
- [root@localhost~]#
在線更改數(shù)據(jù)和元數(shù)據(jù)的結(jié)構(gòu)
- [root@localhost~]#btrfsfidf/btrfs/
- Data,single:total=8.00MiB,used=256.00KiB
- System,DUP:total=8.00MiB,used=16.00KiB
- System,single:total=4.00MiB,used=0.00B
- Metadata,DUP:total=1.00GiB,used=112.00KiB
- Metadata,single:total=8.00MiB,used=0.00B
- GlobalReserve,single:total=16.00MiB,used=0.00B
- [root@localhost~]#btrfsbalancestart-mconvert=raid1/btrfs/#-mconvert為改變metadata元數(shù)據(jù)區(qū)的存儲(chǔ)結(jié)構(gòu)
- Done,hadtorelocate4outof5chunks
- [root@localhost~]#btrfsfish
- Label:'btrfs'uuid:2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Totaldevices2FSbytesused192.00KiB
- devid1size17.00GiBused296.00MiBpath/dev/sdb
- devid2size20.00GiBused288.00MiBpath/dev/sdc
- btrfs-progsv3.19.1
- [root@localhost~]#btrfsfidf/btrfs/
- Data,single:total=8.00MiB,used=64.00KiB
- System,RAID1:total=32.00MiB,used=16.00KiB
- Metadata,RAID1:total=256.00MiB,used=112.00KiB#對(duì)比上改為了raid1
- GlobalReserve,single:total=16.00MiB,used=0.00B
- [root@localhost~]#btrfsbalancestart-dconvert=raid1/btrfs/#-dconvert為改變data數(shù)據(jù)區(qū)的存儲(chǔ)結(jié)構(gòu)
- Done,hadtorelocate1outof3chunks
- [root@localhost~]#btrfsfidf/btrfs/
- Data,RAID1:total=1.00GiB,used=320.00KiB#對(duì)比上面改為了raid1
- System,RAID1:total=32.00MiB,used=16.00KiB
- Metadata,RAID1:total=256.00MiB,used=112.00KiB
- GlobalReserve,single:total=16.00MiB,used=0.00B
- [root@localhost~]#
顯示當(dāng)前文件系統(tǒng)使用信息
- [root@localhostbtrfs]#btrfsfiusage/btrfs/
- Overall:
- Devicesize:37.00GiB#總的空間
- Deviceallocated:2.56GiB#分給元數(shù)據(jù)管理區(qū)的空間
- Deviceunallocated:34.44GiB#未分出去的
- Devicemissing:0.00B
- Used:896.00KiB#使用了的空間
- Free(estimated):18.22GiB(min:18.22GiB)#可用空間,這里因是raid1鏡像卷
- Dataratio:2.00
- Metadataratio:2.00
- Globalreserve:16.00MiB(used:0.00B)
- Data,RAID1:Size:1.00GiB,Used:320.00KiB
- /dev/sdb1.00GiB
- /dev/sdc1.00GiB
- Metadata,RAID1:Size:256.00MiB,Used:112.00KiB
- /dev/sdb256.00MiB
- /dev/sdc256.00MiB
- System,RAID1:Size:32.00MiB,Used:16.00KiB
- /dev/sdb32.00MiB
- /dev/sdc32.00MiB
- Unallocated:
- /dev/sdb15.72GiB#這里2各磁盤分配的空間不同,可以說明btrfs的內(nèi)建raid1不是按物理盤劃分的,而是按chunk,
- /dev/sdc18.72GiB#可以看到具體某塊磁盤的使用狀況。
- [root@localhostbtrfs]#btrfsdevicestats/btrfs/#查看磁盤錯(cuò)誤信息
- [/dev/sdb].write_io_errs0
- [/dev/sdb].read_io_errs0
- [/dev/sdb].flush_io_errs0
- [/dev/sdb].corruption_errs0
- [/dev/sdb].generation_errs0
- [/dev/sdc].write_io_errs0
- [/dev/sdc].read_io_errs0
- [/dev/sdc].flush_io_errs0
- [/dev/sdc].corruption_errs0
- [/dev/sdc].generation_errs0
- [root@localhostbtrfs]#btrfsdeviceusage/btrfs/#磁盤的空間使用狀態(tài)
- /dev/sdb,ID:1
- Devicesize:20.00GiB
- Data,RAID1:1.00GiB
- Metadata,RAID1:256.00MiB
- System,RAID1:32.00MiB
- Unallocated:15.72GiB
- /dev/sdc,ID:2
- Devicesize:20.00GiB
- Data,RAID1:1.00GiB
- Metadata,RAID1:256.00MiB
- System,RAID1:32.00MiB
- Unallocated:18.72GiB
- 壓縮測試
- [root@localhostbtrfs22]#du-sh/btrfs/btrfs22
- 5.1G/btrfs
- 5.1G/btrfs22
- [root@localhostbtrfs22]#btrfsfishow
- Label:'btrfs'uuid:2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Totaldevices2FSbytesused178.63MiB#btrfs掛載采用lzo壓縮,空間被壓縮,因是文本文檔壓縮效果很明顯。
- devid1size17.00GiBused1.28GiBpath/dev/sdb
- devid2size20.00GiBused1.28GiBpath/dev/sdc
- Label:'btrfs22'uuid:d4da4497-b82e-4846-b51c-cd7127ff5c74
- Totaldevices2FSbytesused5.01GiB#btrfs22掛載沒有啟用壓縮功能。
- devid1size20.00GiBused4.04GiBpath/dev/sdd
- devid2size20.00GiBused4.00GiBpath/dev/sde
- btrfs-progsv3.19.1
子卷和快照的管理
- btrfssubvolume
- [root@localhostbtrfs22]#btrfssubvolumecreate/btrfs/btrfs.sub#創(chuàng)建子卷
- Createsubvolume'/btrfs/btrfs.sub'
- [root@localhostbtrfs22]#btrfssubvolumelist/btrfs#顯示子卷
- ID259gen43toplevel5pathbtrfs.sub
- [root@localhostbtrfs22]#umount/btrfs
- [root@localhost~]#mount-osubvol=btrfs.sub/dev/sdc/btrfs.sub/#單獨(dú)掛載子卷
- [root@localhost~]#btrfssubvolumeshow/btrfs.sub/
- /btrfs.sub
- Name:btrfs.sub
- uuid:811deb2f-764f-6440-899c-cddb2b9867e2
- Parentuuid:-
- Creationtime:2016-05-1108:43:51
- ObjectID:259
- Generation(Gen):43
- Genatcreation:43
- Parent:5
- TopLevel:5
- Flags:-
- Snapshot(s):
子卷刪除
- [root@localhost~]#umount/btrfs.sub/#卸卸載子卷
- [root@localhost~]#btrfssubvolumedelete/btrfs/btrfs.sub
- #執(zhí)行刪除命令
- [root@localhost~]#btrfssubvolumelist/btrfs
- #查看已經(jīng)被刪除
- ID260gen45toplevel5pathbtrfs.sub22
子卷快照,類似創(chuàng)建子卷
- [root@localhost~]#btrfssubvolumelist/btrfs
- ID260gen45toplevel5pathbtrfs.sub22
- [root@localhost~]#btrfssubvolumesnapshot/btrfs/btrfs.sub22//btrfs/btrfs.sub22_snapshot
- Createasnapshotof'/btrfs/btrfs.sub22/'in'/btrfs/btrfs.sub22_snapshot'
- [root@localhost~]#btrfssubvolumelist/btrfs
- ID260gen50toplevel5pathbtrfs.sub22
- ID262gen50toplevel5pathbtrfs.sub22_snapshot
單個(gè)文件快照
- [root@localhostbtrfs]#cp--relinkhostnamehostname_snap
- cp:unrecognizedoption'--relink'
- Try'cp--help'formoreinformation.
- [root@localhostbtrfs]#cp--reflinkhostnamehostname_snap
- [root@localhostbtrfs]#cp--reflinkhostnamehostname_snap^C
- [root@localhostbtrfs]#echo"magedu.com">>hostname
- [root@localhostbtrfs]#cathostname
- localhost.localdomain
- magedu.com
- [root@localhostbtrfs]#cathostname_snap
- localhost.localdomain
- [root@localhostbtrfs]#
ext文件系統(tǒng)轉(zhuǎn)換為btrfs
- [root@localhost~]#cp-r/tmp/*/sdf/
- [root@localhost~]#cd/sdf/
- [root@localhostsdf]#ls
- ks-script-OqV4Gblost+foundyum.log
- [root@localhost~]#umount/sdf/#第一步,先卸載需要轉(zhuǎn)換的ext分區(qū)
- [root@localhost~]#fsck-f/dev/sdf#第二步,強(qiáng)制檢測磁盤
- fsckfromutil-linux2.23.2
- e2fsck1.42.9(28-Dec-2013)
- Pass1:Checkinginodes,blocks,andsizes
- Pass2:Checkingdirectorystructure
- Pass3:Checkingdirectoryconnectivity
- Pass4:Checkingreferencecounts
- Pass5:Checkinggroupsummaryinformation
- /dev/sdf:13/1310720files(0.0%non-contiguous),126323/5242880blocks
- [root@localhost~]#btrfs-convert/dev/sdf#第三步,執(zhí)行轉(zhuǎn)換命令
- creatingbtrfsmetadata.
- copyinodes[o][0/13]
- creatingext2fsimagefile.
- cleaningupsystemchunk.
- conversioncomplete.
- [root@localhost~]#mount/dev/sdf/sdf/
- [root@localhost~]#cd/sdf/
- [root@localhostsdf]#ls
- ext2_savedks-script-OqV4Gblost+foundyum.log#轉(zhuǎn)換產(chǎn)生的ext2_saved,不可刪除,刪除就無法轉(zhuǎn)回ext文件系統(tǒng)
- [root@localhostsdf]#catks-script-OqV4Gb#轉(zhuǎn)換后查看文件正常。
- restorecon-ir/etc/sysconfig/network-scripts/var/lib/etc/lvm\
- /dev/etc/iscsi/var/lib/iscsi/root/var/lock/var/log\
- /etc/modprobe.d/etc/sysconfig/var/cache/yum
- #AlsorelabeltheOSTreevariantsofthenormalmounts(iftheyexist)
- restorecon-ir/var/roothome/var/home/var/opt/var/srv/var/media/var/mnt
- restorecon-i/etc/rpm/macros/etc/dasd.conf/etc/zfcp.conf/lib64/usr/lib64\
- /etc/blkid.tab*/etc/mtab/etc/fstab/etc/resolv.conf\
- /etc/modprobe.conf*/var/log/*tmp/etc/crypttab\
- /etc/mdadm.conf/etc/sysconfig/network/root/install.log*\
- /etc/*shadow*/etc/dhcp/dhclient-*.conf/etc/localtime\
- /etc/hostname/root/install.log*
- if[-e/etc/zipl.conf];then
- restorecon-i/etc/zipl.conf
- fi
- [root@localhostsdf]#blkid/dev/sdf
- /dev/sdf:UUID="20bd2176-28d9-49fb-88e9-b746f5ea2736"UUID_SUB="9076e700-22a2-420e-81df-feb79449ab7c"TYPE="btrfs"#查看文件系統(tǒng),已經(jīng)變?yōu)閎trfs
- btrfs轉(zhuǎn)回ext3
- [root@localhost~]#umount/sdf/#第一步,卸載
- [root@localhost~]#btrfs-convert-r/dev/sdf#第二步,執(zhí)行轉(zhuǎn)換命令
- rollbackcomplete.
- [root@localhost~]#blkid/dev/sdf
- /dev/sdf:UUID="8d6c4b81-9602-428a-a340-f01b176fa82b"SEC_TYPE="ext2"TYPE="ext3"#查看轉(zhuǎn)換結(jié)果,已經(jīng)變?yōu)閑tx3格式。
- [root@localhost~]#
總結(jié):初步了解btrfs,首先,擴(kuò)展性基于B-tree架構(gòu),單個(gè)文件,磁盤,文件個(gè)數(shù),大大超過現(xiàn)在對(duì)擴(kuò)展性的要求,其次,數(shù)據(jù)一致性,基于COW和checksum確保數(shù)據(jù)正常(btrfs的數(shù)據(jù)檢測,修復(fù),恢復(fù)相關(guān)的命令操作后面補(bǔ)充),再次,設(shè)備管理功能強(qiáng)大,內(nèi)建raid,聯(lián)機(jī)raid調(diào)整,聯(lián)機(jī)空間擴(kuò)展和縮減,聯(lián)機(jī)物理卷增刪,快照,子卷,可脫離raid和lvm.
以上個(gè)人總結(jié),不足之處歡迎指正,謝謝。
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