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,修復(fù)和易于管理。單文件可達16EB,最大文件數(shù)量2^64,最大卷容量16EB,等。
btrfs功能特性
1,COW:寫時復(fù)制,每次寫入數(shù)據(jù)時,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,可在線擴展和縮減磁盤空間。
3,數(shù)據(jù)和元數(shù)據(jù)校驗碼,checksum
4,子卷,可單獨掛載子卷
5,可寫快照,快照的快照,單個文件快照。
6,透明壓縮
7,ext3/4和btrfs無痛互轉(zhuǎn)
btrfs 基本用法:
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- usage: btrfs [--help] [--version] group> [group>...] command> [args>]
- btrfs subvolume create [-i qgroupid>] [dest>/]name>
- Create a subvolume
- btrfs subvolume delete [options] subvolume> [subvolume>...]
- Delete subvolume(s)
- btrfs subvolume list [options] [-G [+|-]value] [-C [+|-]value] [--sort=gen,ogen,rootid,path] path>
- List subvolumes (and snapshots)
- btrfs subvolume snapshot [-r] [-i qgroupid>] source> dest>|[dest>/]name>
- Create a snapshot of the subvolume
- btrfs subvolume get-default path>
- Get the default subvolume of a filesystem
- btrfs subvolume set-default subvolid> path>
- Set the default subvolume of a filesystem
- btrfs subvolume find-new path> lastgen>
- List the recently modified files in a filesystem
- btrfs subvolume show subvol-path>
- Show more information of the subvolume
- btrfs subvolume sync path> [subvol-id>...]
- Wait until given subvolume(s) are completely removed from the filesystem.
- btrfs filesystem df [options] path>
- Show space usage information for a mount point
- btrfs filesystem show [options] [path>|uuid>|device>|label]
- Show the structure of a filesystem
- btrfs filesystem sync path>
- Force a sync on a filesystem
- btrfs filesystem defragment [options] file>|dir> [file>|dir>...]
- Defragment a file or a directory
- btrfs filesystem resize [devid:][+/-]newsize>[kKmMgGtTpPeE]|[devid:]max path>
- Resize a filesystem
- btrfs filesystem label [device>|mount_point>] [newlabel>]
- Get or change the label of a filesystem
- btrfs filesystem usage [options] path> [path>..]
- Show detailed information about internal filesystem usage .
- btrfs balance start [options] path>
- Balance chunks across the devices
- btrfs balance pause path>
- Pause running balance
- btrfs balance cancel path>
- Cancel running or paused balance
- btrfs balance resume path>
- Resume interrupted balance
- btrfs balance status [-v] path>
- Show status of running or paused balance
- btrfs device add [options] device> [device>...] path>
- Add a device to a filesystem
- btrfs device delete device> [device>...] path>
- Remove a device from a filesystem
- btrfs device scan [(-d|--all-devices)|device> [device>...]]
- Scan devices for a btrfs filesystem
- btrfs device ready device>
- Check device to see if it has all of its devices in cache for mounting
- btrfs device stats [-z] path>|device>
- Show current device IO stats. -z to reset stats afterwards.
- btrfs device usage [options] path> [path>..]
- Show detailed information about internal allocations in devices.
btrfs文件系統(tǒng)管理
為分區(qū)創(chuàng)建btrfs文件系統(tǒng)
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 sectors
- Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
- Disk /dev/sdc: 21.5 GB, 21474836480 bytes, 41943040 sectors
- Disk /dev/sde: 21.5 GB, 21474836480 bytes, 41943040 sectors
- Disk /dev/sdd: 21.5 GB, 21474836480 bytes, 41943040 sectors
創(chuàng)建單分區(qū)btrfs并查看
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- btrfs-progs v3.19.1
- See http://btrfs.wiki.kernel.org for more information.
- Turning ON incompat feature 'extref': increased hardlink limit per file to 65536
- Turning ON incompat feature 'skinny-metadata': reduced-size metadata extent refs
- fs created label btrfs on /dev/sdb
- nodesize 16384 leafsize 16384 sectorsize 4096 size 20.00GiB
- [root@localhost ~]
- Label: 'btrfs' uuid: 2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Total devices 1 FS bytes used 112.00KiB
- devid 1 size 20.00GiB used 2.04GiB path /dev/sdb
- btrfs-progs v3.19.1
- [root@localhost ~]
- [root@localhost ~]
- 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
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- [root@localhost ~]
- Label: 'btrfs' uuid: 2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Total devices 2 FS bytes used 384.00KiB
- devid 1 size 20.00GiB used 2.04GiB path /dev/sdb
- devid 2 size 20.00GiB used 0.00B path /dev/sdc
- btrfs-progs v3.19.1
- [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。
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- Resize '/btrfs/' of '-10G'
- [root@localhost ~]
- Label: 'btrfs' uuid: 2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Total devices 2 FS bytes used 384.00KiB
- devid 1 size 10.00GiB used 2.04GiB path /dev/sdb
- devid 2 size 20.00GiB used 0.00B path /dev/sdc
- btrfs-progs v3.19.1
- [root@localhost ~]
- Resize '/btrfs/' of '+7G'
- [root@localhost ~]
- Label: 'btrfs' uuid: 2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Total devices 2 FS bytes used 384.00KiB
- devid 1 size 17.00GiB used 2.04GiB path /dev/sdb
- devid 2 size 20.00GiB used 0.00B path /dev/sdc
- btrfs-progs v3.19.1
- [root@localhost ~]
在線更改數(shù)據(jù)和元數(shù)據(jù)的結(jié)構(gòu)
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- 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 ~]
- Done, had to relocate 4 out of 5 chunks
- [root@localhost ~]
- Label: 'btrfs' uuid: 2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Total devices 2 FS bytes used 192.00KiB
- devid 1 size 17.00GiB used 296.00MiB path /dev/sdb
- devid 2 size 20.00GiB used 288.00MiB path /dev/sdc
- btrfs-progs v3.19.1
- [root@localhost ~]
- Data, single: total=8.00MiB, used=64.00KiB
- 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 ~]
- Done, had to relocate 1 out of 3 chunks
- [root@localhost ~]
- Data, RAID1: total=1.00GiB, used=320.00KiB
- 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
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost btrfs]
- Overall:
- Device size: 37.00GiB
- Device allocated: 2.56GiB
- Device unallocated: 34.44GiB
- Device missing: 0.00B
- Used: 896.00KiB
- Free (estimated): 18.22GiB(min: 18.22GiB)
- Data ratio: 2.00
- Metadata ratio: 2.00
- Global reserve: 16.00MiB(used: 0.00B)
- Data,RAID1: Size:1.00GiB, Used:320.00KiB
- /dev/sdb 1.00GiB
- /dev/sdc 1.00GiB
- Metadata,RAID1: Size:256.00MiB, Used:112.00KiB
- /dev/sdb 256.00MiB
- /dev/sdc 256.00MiB
- System,RAID1: Size:32.00MiB, Used:16.00KiB
- /dev/sdb 32.00MiB
- /dev/sdc 32.00MiB
- Unallocated:
- /dev/sdb 15.72GiB
- /dev/sdc 18.72GiB
- [root@localhost btrfs]
- [/dev/sdb].write_io_errs 0
- [/dev/sdb].read_io_errs 0
- [/dev/sdb].flush_io_errs 0
- [/dev/sdb].corruption_errs 0
- [/dev/sdb].generation_errs 0
- [/dev/sdc].write_io_errs 0
- [/dev/sdc].read_io_errs 0
- [/dev/sdc].flush_io_errs 0
- [/dev/sdc].corruption_errs 0
- [/dev/sdc].generation_errs 0
- [root@localhost btrfs]
- /dev/sdb, ID: 1
- Device size: 20.00GiB
- Data,RAID1: 1.00GiB
- Metadata,RAID1: 256.00MiB
- System,RAID1: 32.00MiB
- Unallocated: 15.72GiB
- /dev/sdc, ID: 2
- Device size: 20.00GiB
- Data,RAID1: 1.00GiB
- Metadata,RAID1: 256.00MiB
- System,RAID1: 32.00MiB
- Unallocated: 18.72GiB
- 壓縮測試
- [root@localhost btrfs22]
- 5.1G/btrfs
- 5.1G/btrfs22
- [root@localhost btrfs22]
- Label: 'btrfs' uuid: 2a9f0d3d-f8a0-4757-9f4e-d1efa04a683a
- Total devices 2 FS bytes used 178.63MiB
- devid 1 size 17.00GiB used 1.28GiB path /dev/sdb
- devid 2 size 20.00GiB used 1.28GiB path /dev/sdc
- Label: 'btrfs22' uuid: d4da4497-b82e-4846-b51c-cd7127ff5c74
- Total devices 2 FS bytes used 5.01GiB
- devid 1 size 20.00GiB used 4.04GiB path /dev/sdd
- devid 2 size 20.00GiB used 4.00GiB path /dev/sde
- btrfs-progs v3.19.1
子卷和快照的管理
bash/shell Code復(fù)制內(nèi)容到剪貼板
- btrfs subvolume
- [root@localhost btrfs22]
- Create subvolume '/btrfs/btrfs.sub'
- [root@localhost btrfs22]
- ID 259 gen 43 top level 5 path btrfs.sub
- [root@localhost btrfs22]
- [root@localhost ~]
- [root@localhost ~]
- /btrfs.sub
- Name: btrfs.sub
- uuid: 811deb2f-764f-6440-899c-cddb2b9867e2
- Parent uuid: -
- Creation time: 2016-05-11 08:43:51
- Object ID: 259
- Generation (Gen): 43
- Gen at creation: 43
- Parent: 5
- Top Level: 5
- Flags: -
- Snapshot(s):
子卷刪除
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- [root@localhost ~]
-
-
- [root@localhost ~]
-
- ID 260 gen 45 top level 5 path btrfs.sub22
子卷快照,類似創(chuàng)建子卷
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- ID 260 gen 45 top level 5 path btrfs.sub22
- [root@localhost ~]
- Create a snapshot of '/btrfs/btrfs.sub22/' in '/btrfs/btrfs.sub22_snapshot'
- [root@localhost ~]
- ID 260 gen 50 top level 5 path btrfs.sub22
- ID 262 gen 50 top level 5 path btrfs.sub22_snapshot
單個文件快照
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost btrfs]
- cp: unrecognized option '--relink'
- Try 'cp --help' more information.
- [root@localhost btrfs]
- [root@localhost btrfs]
- [root@localhost btrfs]
- [root@localhost btrfs]
- localhost.localdomain
- magedu.com
- [root@localhost btrfs]
- localhost.localdomain
- [root@localhost btrfs]
ext文件系統(tǒng)轉(zhuǎn)換為btrfs
bash/shell Code復(fù)制內(nèi)容到剪貼板
- [root@localhost ~]
- [root@localhost ~]
- [root@localhost sdf]
- ks-script-OqV4Gb lost+found yum.log
- [root@localhost ~]
- [root@localhost ~]
- fsck from util-linux 2.23.2
- e2fsck 1.42.9 (28-Dec-2013)
- Pass 1: Checking inodes, blocks, and sizes
- Pass 2: Checking directory structure
- Pass 3: Checking directory connectivity
- Pass 4: Checking reference counts
- Pass 5: Checking group summary information
- /dev/sdf: 13/1310720 files (0.0% non-contiguous), 126323/5242880 blocks
- [root@localhost ~]
- creating btrfs metadata.
- copy inodes [o] [ 0/ 13]
- creating ext2fs image file.
- cleaning up system chunk.
- conversion complete.
- [root@localhost ~]
- [root@localhost ~]
- [root@localhost sdf]
- ext2_saved ks-script-OqV4Gb lost+found yum.log
- [root@localhost sdf]
- 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
-
- 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@localhost sdf]
- /dev/sdf: UUID="20bd2176-28d9-49fb-88e9-b746f5ea2736" UUID_SUB="9076e700-22a2-420e-81df-feb79449ab7c" TYPE="btrfs"
- btrfs轉(zhuǎn)回ext3
- [root@localhost ~]
- [root@localhost ~]
- rollback complete.
- [root@localhost ~]
- /dev/sdf: UUID="8d6c4b81-9602-428a-a340-f01b176fa82b" SEC_TYPE="ext2" TYPE="ext3"
- [root@localhost ~]
總結(jié):初步了解btrfs,首先,擴展性基于B-tree架構(gòu),單個文件,磁盤,文件個數(shù),大大超過現(xiàn)在對擴展性的要求,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)的命令操作后面補充),再次,設(shè)備管理功能強大,內(nèi)建raid,聯(lián)機raid調(diào)整,聯(lián)機空間擴展和縮減,聯(lián)機物理卷增刪,快照,子卷,可脫離raid和lvm.
以上個人總結(jié),不足之處歡迎指正,謝謝。