# phpman > man > era_invalidate(8)

[era_invalidate(8)](https://www.chedong.com/phpMan.php/man/erainvalidate/8/markdown)                      System Manager's Manual                     [era_invalidate(8)](https://www.chedong.com/phpMan.php/man/erainvalidate/8/markdown)



## NAME
       **era**___**invalidate** - Provide a list of blocks that have changed since a particular era.

## SYNOPSIS
       **era**___**invalidate** [_options_] {device|file}

## DESCRIPTION
       **era**___**invalidate**  examines  era  metadata  and lists blocks that may have changed since a given
       era.

       This tool cannot be run on live metadata unless the **--metadata-snap** option is used.

## OPTIONS
### -h, --help
              Print help and exit.

### -V, --version
              Print version information and exit.

### -o {output file}
              Write output to a file rather than stdout.

### --metadata-snapshot
              Use the metadata snapshot rather than the current superblock.

### --written-since {era nr}
              Blocks written since the given era will be listed.

## EXAMPLE
       List the blocks that may have been written since the beginning of era 13 on the metadata  de‐
       vice /dev/vg/metadata:

           $ era_invalidate --written-since 13 /dev/vg/metadata

       The device may not be actively used by the target when running.

## DIAGNOSTICS
       **era**___**invalidate**  returns  an  exit  code of 0 for success or 1 for error (eg, metadata corrup‐
       tion).

## SEE ALSO
       **era**___**[check**(8)](https://www.chedong.com/phpMan.php/man/check/8/markdown), **era**___**[dump**(8)](https://www.chedong.com/phpMan.php/man/dump/8/markdown), **era**___**[restore**(8)](https://www.chedong.com/phpMan.php/man/restore/8/markdown)

## AUTHOR
       Joe Thornber <<ejt@redhat.com>>



System Manager's Manual                  Device Mapper Tools                       [era_invalidate(8)](https://www.chedong.com/phpMan.php/man/erainvalidate/8/markdown)