LFS-MIRROR-EXTEND(1)

NAME
lfs-mirror-extend - add mirror(s) to an existing file

SYNOPSIS
lfs mirror extend [--bandwidth|--bandwidth-limit|-W BANDWIDTH_MB[MG]] [--fid|-F [--lustre-dir=LUSTRE_MOUNT_POINT]] [--mirror-count|-N[[=]MIRROR_COUNT]] [--no-verify] [--non-direct|-D] [--stats|--stats-interval=SECONDS] [SETSTRIPE_OPTIONS | -f VICTIM_FILE] FILES_FROM

DESCRIPTION
This command adds mirror(s) to existing file(s) specified by FILES_FROM.

The file(s) to be extended can already be a mirrored file, or just a regular non-mirrored file. If it's a non-mirrored file, then the command will convert it to a mirrored file.

FILES_FROM may be:

FILENAME [FILENAME ...]
    File names are listed on command line. Multiple file names are separated by space char.

-0, --null
    Read file names from stdin by default. Each file name is followed by a NUL char. Usually is used after a pipeline from lfs find --print0 command.

--files-from=LIST_FILE
    Read file names from file LIST_FILE. One line for each file name. If LIST_FILE is '-', read from stdin. If --null is specified at the same time, file names are separated by a NUL char.

SETSTRIPE_OPTIONS
    specify the specific layout for the mirror. These are the same options that are used by lfs-setstripe(1). If SETSTRIPE_OPTIONS are not specified, then the stripe options inherited from the previous component will be used. If VICTIM_FILE is specified and exists, then the command will merge the layout from that file as a mirror added to the mirrored file. After the command is finished, the victim file will be removed.

OPTIONS

--chunk-size=SIZE_MB
    The buffer chunk size in MB used to transfer data. It is 1 (MB) by default. But if --aio-tasks=0, the default value is 64 (MB).

-F, --fid
    FID(s) are provided from command line/stdin/LIST_FILE instead of file path(s). Option --lustre-dir= LUSTRE_MOUNT_POINT must be specified at the same time.

-f, --file VICTIM_FILE
    First, the contents of VICTIM_FILE will be verified to be the same as FILENAME. If they are, the layout of VICTIM_FILE will be merged as a mirror added to the mirrored file. Otherwise the layout of VICTIM_FILE will be unchanged. However, --no-verify can be specified to override this check. Once the command is complete VICTIM_FILE will be removed. This option cannot be specified with SETSTRIPE_OPTIONS.

-N, --mirror-count[[=]MIRROR_COUNT]
    Specifies that the next MIRROR_COUNT mirrors will have the following layout. This option can be repeated multiple times to separate mirrors that have different layouts. The MIRROR_COUNT argument is optional and will default to 1 if not specified. This lets a single mirror be specified easily with -N. The --mirror-count|-N option itself is also optional, and if not specified only 1 mirror will be created. The MIRROR_COUNT can be specified with a preceding '=' to indicate the number of total mirrors desired for the layout, such as --mirror-count==TOTAL_MIRROR_COUNT or -N= TOTAL_MIRROR_COUNT. This will create mirrors until the total number of mirrors in the layout is at least TOTAL_MIRROR_COUNT. This also means that if there are already at least TOTAL_MIRROR_COUNT mirrors in the layout then no new mirrors will be created.

--no-verify
    This option indicates not to verify the mirror(s) from victim file(s) in case the victim file(s) contains the same data as the original mirrored file. This option can save siginificant time on file comparison if the file size is large, but it should only be used when the file contents are known to be the same.

--non-direct,-D
    Use buffered, not O_DIRECT, read and write operations when migrating a file. This adds CPU and memory overhead for the data copy between kernel and userspace buffers, but avoids synchronous read and write operations that may slow down small file operations.
    This option cannot be used on encrypted files when the encryption key is not available. It will result in -ENOKEY being returned.

--stats
    This option enables progress updates every 5 seconds, in YAML format.

--stats-interval=STATS_INTERVAL
    This option enables progress updates every STATS_INTERVAL seconds, in YAML format.

-W, --bandwidth BANDWIDTH_MB[MG]
    Limit the read and write bandwidth a mirror extend consumes to no more than BANDWIDTH_MB MiB/s. An optional suffix can be used to specify units in Mebibytes or Gibibytes per second.

EXAMPLES
Add 2 mirrors to /mnt/lustre/file1. If file1 is a non-mirrored file, then the command will convert it to a mirrored file first and then add mirrors. Each mirror has the same default striping pattern with STRIPE_COUNT and STRIPE_SIZE inherited from filesystem-wide default values, and OST POOL_NAME inherited from parent directory:
        # lfs mirror extend -N2 /mnt/lustre/file1

Add 3 PFL mirrors to /mnt/lustre/file1. Each mirror has the same specified PFL layout:
        # lfs mirror extend -N3 -E 1M -c 1 -E 32M -c 4 -S 16M -E eof -c -1 /mnt/lustre/file1

Add 3 plain layout mirrors to /mnt/lustre/file1. The first mirror has a single stripe and 4MB stripe size. The second mirror has two stripes and locates on OSTs with indices 2 and 3 allocated from the flash OST pool. It also has 4MB stripe size inherited from the first mirror. The third mirror has two stripes and 4MB stripe size inherited from the previous mirror, and also has inherited OST POOL_NAME from parent directory:
        # lfs mirror extend -N -c 1 -S 4M -N -c 2 -o 2,3 -p flash -N -p none /mnt/lustre/file1

Add 5 PFL mirrors to /mnt/lustre/file1. The first and second mirrors have the same PFL layout. All of the components are allocated from the flash OST pool. The last three mirrors have the same PFL layout. All of these components have a stripe size of 16MB and use OSTs in the archive pool:
        # lfs mirror extend -N2 -E 4M -c 2 --pool flash -E eof -c 4 -N3 -E 16M -c 4 -S 16M --pool archive -E eof -c -1 /mnt/lustre/file1

Merge the layouts from /mnt/lustre/file2 and /mnt/lustre/file3, which contain the same data as /mnt/lustre/file1, use the layouts as mirrors and add them to /mnt/lustre/file1 without verification:
        # lfs mirror extend --no-verify -N -f /mnt/lustre/file2 -N -f /mnt/lustre/file3 /mnt/lustre/file1

AVAILABILITY
The lfs mirror extend 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-resync(1), lfs-mirror-split(1), lfs-mirror-verify(1), lfs-setstripe(1)