NAME

       pmempool_check_init(), pmempool_check(), pmempool_check_end() - checks pmempool health

SYNOPSIS

              #include <libpmempool.h>

              PMEMpoolcheck *pmempool_check_init(struct pmempool_check_args *args,
                  size_t args_size);
              struct pmempool_check_status *pmempool_check(PMEMpoolcheck *ppc);
              enum pmempool_check_result pmempool_check_end(PMEMpoolcheck *ppc);

DESCRIPTION

       To  perform  the checks provided by libpmempool, a check context must first be initialized
       using the pmempool_check_init() function described in this section.  Once initialized, the
       check  context  is represented by an opaque handle of type PMEMpoolcheck*, which is passed
       to all of the other functions available in libpmempool

       To execute checks, pmempool_check() must be called iteratively.  Each call generates a new
       check  status,  represented  by a struct pmempool_check_status structure.  Status messages
       are described later below.

       When the checks are completed, pmempool_check() returns NULL.  The check must be finalized
       using  pmempool_check_end(),  which  returns  an enum pmempool_check_result describing the
       results of the entire check.

       pmempool_check_init() initializes the check context.  args  describes  parameters  of  the
       check  context.   args_size should be equal to the size of the struct pmempool_check_args.
       struct pmempool_check_args is defined as follows:

              struct pmempool_check_args
              {
                  /* path to the pool to check */
                  const char *path;

                  /* optional backup path */
                  const char *backup_path;

                  /* type of the pool */
                  enum pmempool_pool_type pool_type;

                  /* parameters */
                  int flags;
              };

       The flags argument accepts any combination of the following values (ORed):

       • PMEMPOOL_CHECK_REPAIR - perform repairs

       • PMEMPOOL_CHECK_DRY_RUN - emulate repairs, not supported on Device DAX

       • PMEMPOOL_CHECK_ADVANCED - perform hazardous repairs

       • PMEMPOOL_CHECK_ALWAYS_YES - do not ask before repairs

       • PMEMPOOL_CHECK_VERBOSE - generate info statuses

       • PMEMPOOL_CHECK_FORMAT_STR - generate string format statuses

       pool_type must match the type of the pool being processed.  Pool  type  detection  may  be
       enabled  by setting pool_type to PMEMPOOL_POOL_TYPE_DETECT.  A pool type detection failure
       ends the check.

       backup_path may be:

       • NULL.  No backup will be performed.

       • a non-existent file: backup_path will be created and backup  will  be  performed.   path
         must be a single file pool.

       • an  existing  pool set file: Backup will be performed as defined by the backup_path pool
         set.  path must be a pool set, and backup_path must have the same  structure  (the  same
         number of parts with exactly the same size) as the path pool set.

       Backup is supported only if the source pool set has no defined replicas.

       The pmempool_check() function starts or resumes the check indicated by ppc.  When the next
       status is generated, the check is paused and pmempool_check() returns  a  pointer  to  the
       struct pmempool_check_status structure:

              struct pmempool_check_status
              {
                  enum pmempool_check_msg_type type; /* type of the status */
                  struct
                  {
                      const char *msg; /* status message string */
                      const char *answer; /* answer to message if applicable */
                  } str;
              };

       This structure can describe three types of statuses:

       • PMEMPOOL_CHECK_MSG_TYPE_INFO  - detailed information about the check.  Generated only if
         a PMEMPOOL_CHECK_VERBOSE flag was set.

       • PMEMPOOL_CHECK_MSG_TYPE_ERROR - An error was encountered.

       • PMEMPOOL_CHECK_MSG_TYPE_QUESTION    -    question.      Generated     only     if     an
         PMEMPOOL_CHECK_ALWAYS_YES  flag  was  not set.  It requires answer to be set to “yes” or
         “no” before continuing.

       After calling pmempool_check() again, the previously provided struct pmempool_check_status
       pointer must be considered invalid.

       The  pmempool_check_end() function finalizes the check and releases all related resources.
       ppc is invalid after calling pmempool_check_end().

RETURN VALUE

       pmempool_check_init() returns an opaque handle of type PMEMpoolcheck*.   If  the  provided
       parameters  are invalid or the initialization process fails, pmempool_check_init() returns
       NULL and sets errno appropriately.

       Each call  to  pmempool_check()  returns  a  pointer  to  a  struct  pmempool_check_status
       structure  when a status is generated.  When the check completes, pmempool_check() returns
       NULL.

       The pmempool_check_end() function returns an enum  pmempool_check_result  summarizing  the
       results  of  the  finalized  check.   pmempool_check_end() can return one of the following
       values:

       • PMEMPOOL_CHECK_RESULT_CONSISTENT - the pool is consistent

       • PMEMPOOL_CHECK_RESULT_NOT_CONSISTENT - the pool is not consistent

       • PMEMPOOL_CHECK_RESULT_REPAIRED - the pool has issues  but  all  repair  steps  completed
         successfully

       • PMEMPOOL_CHECK_RESULT_CANNOT_REPAIR - the pool has issues which can not be repaired

       • PMEMPOOL_CHECK_RESULT_ERROR - the pool has errors or the check encountered an issue

       • PMEMPOOL_CHECK_RESULT_SYNC_REQ  - the pool has single healthy replica.  To fix remaining
         issues use pmempool_sync(3).

EXAMPLE

       This is an example of a check context initialization:

              struct pmempool_check_args args =
              {
                  .path = "/path/to/blk.pool",
                  .backup_path = NULL,
                  .pool_type = PMEMPOOL_POOL_TYPE_BLK,
                  .flags = PMEMPOOL_CHECK_REPAIR | PMEMPOOL_CHECK_DRY_RUN |
                      PMEMPOOL_CHECK_VERBOSE | PMEMPOOL_CHECK_FORMAT_STR
              };

              PMEMpoolcheck *ppc = pmempool_check_init(&args, sizeof(args));

       The check will  process  a  pool  of  type  PMEMPOOL_POOL_TYPE_BLK  located  in  the  path
       /path/to/blk.pool.   Before the check it will not create a backup of the pool (backup_path
       ==  NULL).   If  the  check  finds  any  issues  it  will  try  to  perform  repair  steps
       (PMEMPOOL_CHECK_REPAIR),    but   it   will   not   make   any   changes   to   the   pool
       (PMEMPOOL_CHECK_DRY_RUN)  and  it  will  not  perform  any  dangerous  repair  steps   (no
       PMEMPOOL_CHECK_ADVANCED).   The  check  will  ask  before  performing any repair steps (no
       PMEMPOOL_CHECK_ALWAYS_YES).  It will also generate detailed information  about  the  check
       (PMEMPOOL_CHECK_VERBOSE).   The  PMEMPOOL_CHECK_FORMAT_STR  flag  indicates  string format
       statuses (struct pmempool_check_status).  Currently this  is  the  only  supported  status
       format so this flag is required.

NOTES

       Currently, checking the consistency of a pmemobj pool is not supported.

SEE ALSO

       libpmemlog(7), libpmemobj(7) and <https://pmem.io>