{"id":3195,"date":"2022-12-20T16:43:46","date_gmt":"2022-12-20T19:43:46","guid":{"rendered":"http:\/\/lode.uno\/linux-man\/index.php\/2022\/12\/20\/btrfsconvert-man8\/"},"modified":"2022-12-20T16:43:46","modified_gmt":"2022-12-20T19:43:46","slug":"btrfsconvert-man8","status":"publish","type":"post","link":"https:\/\/lode.uno\/linux-man\/2022\/12\/20\/btrfsconvert-man8\/","title":{"rendered":"BTRFS−CONVERT (man8)"},"content":{"rendered":"

BTRFS\u2212CONVERT<\/h1>\n

NAME<\/a>
SYNOPSIS<\/a>
DESCRIPTION<\/a>
OPTIONS<\/a>
EXIT STATUS<\/a>
SEE ALSO<\/a> <\/p>\n

\n

NAME <\/a> <\/h2>\n

btrfs-convert \u2212 convert from ext2\/3\/4 or reiserfs filesystem to btrfs in\u2212place<\/p>\n

SYNOPSIS <\/a> <\/h2>\n

btrfs\u2212convert<\/b> [options] <\/i><\/p>\n

DESCRIPTION <\/a> <\/h2>\n

btrfs\u2212convert<\/b><\/i> is used to convert existing source filesystem image to a btrfs filesystem in\u2212place. The original filesystem image is accessible in subvolume named like ext2_saved<\/i> as file image<\/i>.<\/p>\n

Supported filesystems:<\/p>\n

\u2022 ext2, ext3, ext4 \u2014 original feature, always built in<\/p>\n

\u2022 reiserfs \u2014 since version 4.13, optionally built, requires libreiserfscore 3.6.27<\/p>\n

\u2022 ntfs \u2014 external tool https:\/\/github.com\/maharmstone\/ntfs2btrfs<\/font><\/b><\/p>\n

The list of supported source filesystem by a given binary is listed at the end of help (option \u2212\u2212help<\/i>).<\/font><\/p>\n

Warning<\/big><\/b>
If you are going to perform rollback to the original filesystem, you should not execute btrfs balance<\/b> command on the converted filesystem. This will change the extent layout and make btrfs\u2212convert<\/b> unable to rollback.<\/font><\/p>\n

The conversion utilizes free space of the original filesystem. The exact estimate of the required space cannot be foretold. The final btrfs metadata might occupy several gigabytes on a hundreds\u2212gigabyte filesystem.<\/font><\/p>\n

If the ability to rollback is no longer important, the it is recommended to perform a few more steps to transition the btrfs filesystem to a more compact layout. This is because the conversion inherits the original data blocks’ fragmentation, and also because the metadata blocks are bound to the original free space layout.<\/font><\/p>\n

Due to different constraints, it is only possible to convert filesystems that have a supported data block size (ie. the same that would be valid for mkfs.btrfs<\/i>). This is typically the system page size (4KiB on x86_64 machines).<\/font><\/p>\n

BEFORE YOU START<\/b><\/font><\/p>\n

The source filesystem must be clean, eg. no journal to replay or no repairs needed. The respective fsck<\/i> utility must be run on the source filesytem prior to conversion. Please refer to the manual pages in case you encounter problems.<\/font><\/p>\n

For ext2\/3\/4:<\/font><\/p>\n

# e2fsck \u2212fvy \/dev\/sdx<\/font><\/p>\n

For reiserfs:<\/font><\/p>\n

# reiserfsck \u2212fy \/dev\/sdx<\/font><\/p>\n

Skipping that step could lead to incorrect results on the target filesystem, but it may work.<\/font><\/p>\n

REMOVE THE ORIGINAL FILESYSTEM METADATA<\/b><\/font><\/p>\n

By removing the subvolume named like ext2_saved<\/i> or reiserfs_saved<\/i>, all metadata of the original filesystem will be removed:<\/font><\/p>\n

# btrfs subvolume delete \/mnt\/ext2_saved<\/font><\/p>\n

At this point it is not possible to do a rollback. The filesystem is usable but may be impacted by the fragmentation inherited from the original filesystem.<\/font><\/p>\n

MAKE FILE DATA MORE CONTIGUOUS<\/b><\/font><\/p>\n

An optional but recommended step is to run defragmentation on the entire filesystem. This will attempt to make file extents more contiguous.<\/font><\/p>\n

# btrfs filesystem defrag \u2212v \u2212r \u2212f \u2212t 32M \/mnt\/btrfs<\/font><\/p>\n

Verbose recursive defragmentation (\u2212v<\/i>, \u2212r<\/i>), flush data per\u2212file (\u2212f<\/i>) with target extent size 32MiB (\u2212t<\/i>).<\/font><\/p>\n

ATTEMPT TO MAKE BTRFS METADATA MORE COMPACT<\/b><\/font><\/p>\n

Optional but recommended step.<\/font><\/p>\n

The metadata block groups after conversion may be smaller than the default size (256MiB or 1GiB). Running a balance will attempt to merge the block groups. This depends on the free space layout (and fragmentation) and may fail due to lack of enough work space. This is a soft error leaving the filesystem usable but the block group layout may remain unchanged.<\/font><\/p>\n

Note that balance operation takes a lot of time, please see also btrfs\u2212balance<\/b>(8).<\/font><\/p>\n

# btrfs balance start \u2212m \/mnt\/btrfs<\/font><\/p>\n

OPTIONS <\/a> <\/h2>\n

\u2212\u2212csum <\/i>, \u2212\u2212checksum <\/i><\/big><\/font><\/p>\n

Specify the checksum algorithm. Default is crc32c<\/i>. Valid values are crc32c<\/i>, xxhash<\/i>, sha256<\/i> or blake2<\/i>. To mount such filesystem kernel must support the checksums as well.<\/big><\/font><\/p>\n

\u2212d|\u2212\u2212no\u2212datasum<\/big><\/font><\/p>\n

disable data checksum calculations and set the NODATASUM file flag, this can speed up the conversion<\/big><\/font><\/p>\n

\u2212i|\u2212\u2212no\u2212xattr<\/big><\/font><\/p>\n

ignore xattrs and ACLs of files<\/big><\/font><\/p>\n

\u2212n|\u2212\u2212no\u2212inline<\/big><\/font><\/p>\n

disable inlining of small files to metadata blocks, this will decrease the metadata consumption and may help to convert a filesystem with low free space<\/big><\/font><\/p>\n

\u2212N|\u2212\u2212nodesize <\/i><\/big><\/font><\/p>\n

set filesystem nodesize, the tree block size in which btrfs stores its metadata. The default value is 16KB (16384) or the page size, whichever is bigger. Must be a multiple of the sectorsize, but not larger than 65536. See mkfs.btrfs<\/b>(8) for more details.<\/big><\/font><\/p>\n

\u2212r|\u2212\u2212rollback<\/big><\/font><\/p>\n

rollback to the original ext2\/3\/4 filesystem if possible<\/big><\/font><\/p>\n

\u2212l|\u2212\u2212label

set filesystem label during conversion<\/big><\/font><\/p>\n

\u2212L|\u2212\u2212copy\u2212label<\/big><\/font><\/p>\n

use label from the converted filesystem<\/big><\/font><\/p>\n

\u2212O|\u2212\u2212features <\/i>[,<\/i>…]<\/big><\/font><\/p>\n

A list of filesystem features enabled the at time of conversion. Not all features are supported by old kernels. To disable a feature, prefix it with ^<\/i>. Description of the features is in section FILESYSTEM FEATURES<\/i> of mkfs.btrfs<\/b>(8).<\/big><\/font><\/p>\n

To see all available features that btrfs\u2212convert supports run:<\/big><\/font><\/p>\n

btrfs\u2212convert \u2212O list\u2212all<\/b><\/big><\/font><\/p>\n

\u2212p|\u2212\u2212progress<\/big><\/font><\/p>\n

show progress of conversion (a heartbeat indicator and number of inodes processed), on by default<\/big><\/font><\/p>\n

\u2212\u2212no\u2212progress<\/big><\/font><\/p>\n

disable progress and show only the main phases of conversion<\/big><\/font><\/p>\n

\u2212\u2212uuid <\/i><\/big><\/font><\/p>\n

set the FSID of the new filesystem based on SPEC<\/i>:<\/big><\/font><\/p>\n

\u2022 new<\/i> \u2212 (default) generate UUID for the FSID of btrfs<\/big><\/font><\/p>\n

\u2022 copy<\/i> \u2212 copy UUID from the source filesystem<\/big><\/font><\/p>\n

\u2022 UUID<\/i> \u2212 a conforming UUID value, the 36 byte string representation<\/big><\/font><\/p>\n

EXIT STATUS <\/a> <\/h2>\n

btrfs\u2212convert<\/b> will return 0 if no error happened. If any problems happened, 1 will be returned.<\/big><\/font><\/p>\n

SEE ALSO <\/a> <\/h2>\n

mkfs.btrfs<\/b>(8)<\/big><\/font><\/p>\n

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btrfs-convert \u2212 convert from ext2\/3\/4 or reiserfs filesystem to btrfs in\u2212place <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[5,52,337,4],"class_list":["post-3195","post","type-post","status-publish","format-standard","hentry","category-8-administracion-del-sistema","tag-5","tag-administracion","tag-btrfs-convert","tag-man8"],"gutentor_comment":0,"_links":{"self":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts\/3195","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/comments?post=3195"}],"version-history":[{"count":0,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts\/3195\/revisions"}],"wp:attachment":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/media?parent=3195"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/categories?post=3195"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/tags?post=3195"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}