lfs-mirror-split(1)

NAME

lfs-mirror-split - split a specified mirror from an existing mirrored file

SYNOPSIS

DESCRIPTION

This command splits a mirror with mirror ID MIRROR_ID or containing a component with COMP_ID or containing a component on POOL out of a mirrored file specified by the path name MIRRORED_FILE. By default, the layout of the split mirror will be stored into a new file named MIRRORED_FILE.mirror~MIRROR_ID. If -f NEW_FILE option is specified, then the layout of the split mirror will be stored into the named file.

If MIRRORED_FILE has only one mirror existing after split, it will be converted to a regular non-mirrored file.

If the split target is a data mirror that has an associated erasure coding (EC) parity mirror, the MDS will atomically split (or destroy) the parity mirror along with the data mirror in a single operation. Splitting the last data mirror out of MIRRORED_FILE is refused, since a file left holding parity mirrors alone cannot be read; so is a split that would remove every mirror. A lone data and parity mirror pair therefore cannot be taken apart by splitting the data mirror; destroy the parity mirror instead, with -d or lfs mirror delete, to turn the file back into a plain data file. A parity mirror can only be destroyed, never moved to a file of its own: both a plain --mirror-id MIRROR_ID split and one with -f NEW_FILE are refused, since a file holding only a parity mirror cannot be read. Destroying a parity mirror prints a warning when it takes away the last redundant copy of the file, since the data mirror it protected is then left alone. No warning is printed while another data mirror remains, and --no-warn suppresses it entirely.

If the original MIRRORED_FILE is not a mirrored file, then the command will return an error.

OPTIONS

--mirror-id MIRROR_ID

The numerical unique identifier for a mirror. The mirror ID is unique within a mirrored file and is automatically assigned at file creation or extension time. It can be fetched by lfs getstripe command (see lfs(1)).

--comp-id COMP_ID

The numerical unique identifier for a component contained within a mirror.

--pool POOL

The pool storing a component contained within a mirror.

-d, --destroy

This option indicates the split mirror will be destroyed.

This option is mandatory on encrypted files when the encryption key is not available. Otherwise operation results in -ENOKEY.

--no-warn

Do not print the warning issued when the operation removes the last redundant copy of the file.

-f NEW_FILE

This option indicates the layout of the split mirror will be stored into NEW_FILE. If the split mirror is an EC data mirror, both the data and its associated parity mirror will be moved to NEW_FILE. This option is refused for an EC parity mirror, since NEW_FILE would then hold only parity and could not be read; use -d or lfs mirror delete to remove it instead.

This option cannot be used on encrypted files when the encryption key is not available. It will result in -ENOKEY.

EXAMPLES

Split a mirror with ID 1 out of /mnt/lustre/file1 and store it into /mnt/lustre/file1.mirror~1:

# lfs mirror split --mirror-id 1 /mnt/lustre/file1

Split a mirror with ID 2 out of /mnt/lustre/file1 and destroy it:

# lfs mirror split --mirror-id 2 -d /mnt/lustre/file1

Split a mirror with ID 3 out of /mnt/lustre/file1 and store it into /mnt/lustre/file2:

# lfs mirror split --mirror-id 3 -f /mnt/lustre/file2 /mnt/lustre/file1

Split a mirror containing the component with ID 65537 out of /mnt/lustre/file1 and destroy it:

# lfs mirror split --comp-id 65537 -d /mnt/lustre/file1

Split a mirror on pool lustre-nvme out of /mnt/lustre/file1 and destroy it:

# lfs mirror split --pool lustre-nvme -d /mnt/lustre/file1

Split the data mirror with ID 1 out of an EC mirrored file that has another data mirror as well, and destroy it. The parity mirror associated with mirror 1 is also destroyed automatically:

# lfs mirror split --mirror-id 1 -d /mnt/lustre/ecfile

Destroy the parity mirror with ID 2 of an EC mirrored file. A warning is printed if this leaves its data mirror without a redundant copy; pass --no-warn to suppress it:

# lfs mirror split --mirror-id 2 -d /mnt/lustre/ecfile

AVAILABILITY

The lfs mirror split command is part of the lustre(7) filesystem package since release 2.11.0

SEE ALSO

lfs(1), lfs-mirror-create(1), lfs-mirror-delete(1), lfs-mirror-extend(1), lfs-mirror-resync(1), lfs-mirror-verify(1), lfs-setstripe(1)