pmempool-feature1

Usage

Overview

The pmempool feature command enables / disables or queries pool set features.

Available pool feature-names are:

•

SINGLEHDR - only the first part in each replica contains the pool part internal metadata. This value can be used only with -q. It can not be enabled or disabled. For details see poolset(5).

•

CHECKSUM_2K - only the first 2KiB of pool part internal metadata is checksummed. Other features may depend on this one to store additional metadata in otherwise unused second 2KiB part of a header. When CHECKSUM_2K is disabled whole 4KiB is checksummed.

•

SHUTDOWN_STATE - enables additional check performed during pool open which verifies pool consistency in the presence of dirty shutdown. CHECKSUM_2K has to be enabled prior to SHUTDOWN_STATE otherwise enabling SHUTDOWN_STATE will fail.

•

CHECK_BAD_BLOCKS - enables checking bad blocks performed during opening a pool and fixing bad blocks performed by pmempool-sync during syncing a pool. Currently (Linux kernel v4.19, libndctl v62) checking and fixing bad blocks require read access to the following resource files (containing physical addresses) of NVDIMM devices which only root can read by default:

/sys/bus/nd/devices/ndbus*/region*/resource
/sys/bus/nd/devices/ndbus*/region*/dax*/resource
/sys/bus/nd/devices/ndbus*/region*/pfn*/resource
/sys/bus/nd/devices/ndbus*/region*/namespace*/resource

It is possible to use poolset as file argument.

Compatibility

Poolsets with features not defined in this document (e.g. enabled by the newer software version) are not supported.

Disclaimer

pmempool feature command is not fail safe.

Examples

$ pmempool feature --enable CHECKSUM_2K pool.set

Enables POOL_FEAT_CKSUM_2K incompat feature flag.

$ pmempool feature --disable CHECKSUM_2K pool.set

Disables POOL_FEAT_CKSUM_2K incompat feature flag.

$ pmempool feature --query CHECKSUM_2K pool.set
0

Prints POOL_FEAT_CKSUM_2K incompat feature flag value.