About btrfs file system
btrfs file system: Technology Preview (Centos7)
Btrfs (B-Tree, Butter FS, of Better FS), the GPL licensed, Orale2007 is proposed to replace your Ext file system
core features:
1, and more physical volumes support: supports multiple underlying physical devices are organized into a single file system, similar to VG, btrfs may be more underlying physical volumes, support for RAID, in order to achieve the physical volume of online "add, remove, modify,"
2, write copy update mechanism (CoW): copy, update and replace pointer, rather than "in-place update"
when not modify files, copy files without file content, data pointer still points to the original file
when you modify a file, do not modify the source file immediately, but will a copy of the source file, copy the file to the newly generated modified, and then copy the file to the file name points to the new generation of source files to retain, easy data recovery.
replication features (Cow) write
cp --reflink (only btrfs using the file system)
3, check code data and metadata mechanism: when each file is stored, the metadata file checksum and the check code data, property extension files saved by the access. When files by scanning the check code, can quickly determine whether a file damaged, once damaged, automatically tries to fix maximum reliability to ensure data
4, support for sub-volume (sub_volume): create a lot of volume on a sub roll, each sub volume can be achieved using the mount alone and
5, a snapshot: write-based replication mechanism than a snapshot lvm, increasing the difference (incremental) snapshots, you can take a snapshot of a snapshot after snapshot file complete change again snapshot.
6, the transparent compression scheme: In this document we want to save storage space partition, any data stream can be sent to the file system btrfs, automatically store data compression cycle is completed, the user can not perceive, but are automatically uncompressed read consume. the cpu clock cycle
btrfs file system:
volume Creation:
mkfs.btrfs [Options] <Device> [<Device> ...]
-L 'the label' set volume label
-d <data-profile> specifies the type of data store {raid0 , raid1, raid5, raid6, raid10 , single ( single file), dup (redundant)}
-m <metadata-Profile> specifies the type of the metadata stored RAID0 {, RAID1, RAID5, RAID6, RAID10, sINGLE, DUP}
-O <feature> specifies opened when formatting features
-O list-all feature lists all the supported
attributes View:
btrfs filesystem show here in the following commands are in btrfs
list the current file system, btrfs, and displays information
plus a <dEVICE> displays information about the specified device
mount:
Mount [-t btrfs] / dev / sdb MOUNT_POINT
-t is optional alternative
to / dev / sdb exemplary system do btrfs
transparent compression schemes:
explanation: automatically writing compression, decompression automatically read;[Un] compress process hidden from the user
-o = {LZO the compress Mount |} zlib the DEVICE MOUNT_POINT
LZO, zlib compression algorithm
btrfs command, subcommand, sub subcommand:
btrfs filesystem
Show View all system information btrfs
df <MOUNT_POINT> See mounted particular space usage
resize <MOUNT_POINT > online / online change the size, reduce the capacity to modify risk, operations need to be cautious
btrfs Device
btrfs the Add Device <NEW_DEVCIE> <MOUNT_POINT> add a disk to mount point
btrfs device delete <OLD_DEVCIE> <MOUNT_POINT > delete to mount a disk point
btrfs-balance load balancing
btrfs balance start <MOUNT_POINT> to start the process of balancing the load
state to see balanced progress
pause pause
resume continues to
cancel canceled
load balancing system performance will consume a large part of the operation it is only recommended when not busy; can use pause pause ;
Btrfs Balance Start -mconvert = <Profile> <MOUNT_POINT> modified raid level
<Profile>: RAID0, RAID1, RAID10, RAID5, RAID6, DUP, SINGLE
-dconvert data area Blocks Data
-mconvert metadata area of chunks are Metadata
-sconvert system area of chunks are System (The requires -f)
Btrfs subvolume sub-volume
mount subvolume :
Mount -o subvol = '' / dev / MOUNT_POIN the DEVICE
# to be mounted to view the subvolume ID
# Btrfs subvolume list / mnt / BTRF
ID Gen. 9 Top Level 256 SU path. 5
or may be mounted through a path
list show all subvolume
create create a sub-volume
delete delete sub-volume
Note: delete sub-volume will not actually delete the data on the physical volume, such as the need to use -c
Snapshot
btrfs subvolume Snapshot / MOUNT_POINT / sUB / MOUNT_POINT / SUB_snapsho
btrfs-convert For conversion to other formats Btrfs
Btrfs-convert </ dev / the DEVICE> fs to convert other Btrfs
-R & lt rollback to the original fs
Command Note:
Btrfs command to mount the operation target point after loading, the non-operating device file / dev / sd [az]
About btrfs file system
btrfs file system: Technology Preview (Centos7)
Btrfs (B-Tree, Butter FS, of Better FS), the GPL licensed, Orale2007 is proposed to replace your Ext file system
core features:
1, and more physical volumes support: supports multiple underlying physical devices are organized into a single file system, similar to VG, btrfs may be more underlying physical volumes, support for RAID, in order to achieve the physical volume of online "add, remove, modify,"
2, write copy update mechanism (CoW): copy, update and replace pointer, rather than "in-place update"
when not modify files, copy files without file content, data pointer still points to the original file
when you modify a file, do not modify the source file immediately, but will a copy of the source file, copy the file to the newly generated modified, and then copy the file to the file name points to the new generation of source files to retain, easy data recovery.
replication features (Cow) write
cp --reflink (only btrfs using the file system)
3, check code data and metadata mechanism: when each file is stored, the metadata file checksum and the check code data, property extension files saved by the access. When files by scanning the check code, can quickly determine whether a file damaged, once damaged, automatically tries to fix maximum reliability to ensure data
4, support for sub-volume (sub_volume): create a lot of volume on a sub roll, each sub volume can be achieved using the mount alone and
5, a snapshot: write-based replication mechanism than a snapshot lvm, increasing the difference (incremental) snapshots, you can take a snapshot of a snapshot after snapshot file complete change again snapshot.
6, the transparent compression scheme: In this document we want to save storage space partition, any data stream can be sent to the file system btrfs, automatically store data compression cycle is completed, the user can not perceive, but are automatically uncompressed read consume. the cpu clock cycle
btrfs file system:
volume Creation:
mkfs.btrfs [Options] <Device> [<Device> ...]
-L 'the label' set volume label
-d <data-profile> specifies the type of data store {raid0 , raid1, raid5, raid6, raid10 , single ( single file), dup (redundant)}
-m <metadata-Profile> specifies the type of the metadata stored RAID0 {, RAID1, RAID5, RAID6, RAID10, sINGLE, DUP}
-O <feature> specifies opened when formatting features
-O list-all feature lists all the supported
attributes View:
btrfs filesystem show here in the following commands are in btrfs
list the current file system, btrfs, and displays information
plus a <dEVICE> displays information about the specified device
mount:
Mount [-t btrfs] / dev / sdb MOUNT_POINT
-t is optional alternative
to / dev / sdb exemplary system do btrfs
transparent compression schemes:
explanation: automatically writing compression, decompression automatically read;[Un] compress process hidden from the user
-o = {LZO the compress Mount |} zlib the DEVICE MOUNT_POINT
LZO, zlib compression algorithm
btrfs command, subcommand, sub subcommand:
btrfs filesystem
Show View all system information btrfs
df <MOUNT_POINT> See mounted particular space usage
resize <MOUNT_POINT > online / online change the size, reduce the capacity to modify risk, operations need to be cautious
btrfs Device
btrfs the Add Device <NEW_DEVCIE> <MOUNT_POINT> add a disk to mount point
btrfs device delete <OLD_DEVCIE> <MOUNT_POINT > delete to mount a disk point
btrfs-balance load balancing
btrfs balance start <MOUNT_POINT> to start the process of balancing the load
state to see balanced progress
pause pause
resume continues to
cancel canceled
load balancing system performance will consume a large part of the operation it is only recommended when not busy; can use pause pause ;
Btrfs Balance Start -mconvert = <Profile> <MOUNT_POINT> modified raid level
<Profile>: RAID0, RAID1, RAID10, RAID5, RAID6, DUP, SINGLE
-dconvert data area Blocks Data
-mconvert metadata area of chunks are Metadata
-sconvert system area of chunks are System (The requires -f)
Btrfs subvolume sub-volume
mount subvolume :
Mount -o subvol = '' / dev / MOUNT_POIN the DEVICE
# to be mounted to view the subvolume ID
# Btrfs subvolume list / mnt / BTRF
ID Gen. 9 Top Level 256 SU path. 5
or may be mounted through a path
list show all subvolume
create create a sub-volume
delete delete sub-volume
Note: delete sub-volume will not actually delete the data on the physical volume, such as the need to use -c
Snapshot
btrfs subvolume Snapshot / MOUNT_POINT / sUB / MOUNT_POINT / SUB_snapsho
btrfs-convert For conversion to other formats Btrfs
Btrfs-convert </ dev / the DEVICE> fs to convert other Btrfs
-R & lt rollback to the original fs
Command Note:
Btrfs command to mount the operation target point after loading, the non-operating device file / dev / sd [az]