pmempool-sync man page

pmempool-sync — Synchronize replicas or their parts within a pool set.

Synopsis

pmempool sync [options] <poolset_file>

NOTE: Only the pool set file used to create the pool should be used for syncing the pool.

Description

The pmempool sync command synchronizes data between replicas within a pool set. It checks if metadata of all replicas in a pool set are consistent, i.e. all parts are healthy, and if any of them is not, the corrupted or missing parts are recreated and filled with data from one of the healthy replicas. Currently synchronizing data is allowed only for pmemobj pools (see libpmemobj(7)).

If a pool set has the option SINGLEHDR or NOHDRS (see poolset(5)), pmempool sync command has limited capability of checking its metadata. This is due to limited or no, respectively, internal metadata at the beginning of pool set parts in every replica when either of the options is used. In that cases, only missing parts or the ones which cannot be opened are recreated.

Available options

-b--bad-blocks

Fix bad blocks - it causes creating or reading special recovery files. When bad blocks are detected, special recovery files have to be created in order to fix them safely. A separate recovery file is created for each part of the pool. The recovery files are created in the same directory where the poolset file is located using the following name pattern: <poolset-file-name> _r <replica-number> _p <part-number> _badblocks.txt These recovery files are automatically removed if the sync operation finishes successfully.

If the last sync operation was interrupted and not finished correctly (eg. the application crashed) and the bad blocks fixing procedure was in progress, the bad block recovery files may be left over. In such case bad blocks might have been cleared and zeroed, but the correct data from these blocks was not recovered (not copied from a healthy replica), so the recovery files MUST NOT be deleted manually, because it would cause a data loss. Pmempool-sync should be run again with the `-b' option set. It will finish the previously interrupted sync operation and copy correct data to zeroed bad blocks using the left-over bad block recovery files (the bad blocks will be read from the saved recovery files). Pmempool will delete the recovery files automatically at the end of the sync operation.

Using this option may have limitations depending on the operating system. For details see description of the CHECK_BAD_BLOCKS feature in pmempool-feature(1).

-d--dry-run

Enable dry run mode. In this mode no changes are applied, only check for viability of synchronization.

-v--verbose

Increase verbosity level.

-h--help

Display help message and exit.

See Also

pmempool(1), libpmemblk(7), libpmemlog(7), libpmempool(7) and <http://pmem.io>

Referenced By

pmempool(1), poolset(5).

2019-07-10 PMDK - pmem Tools version 1.4 PMDK Programmer's Manual