bionic (1) ndctl-destroy-namespace.1.gz

Provided by: ndctl_61.2-0ubuntu1~18.04.1_amd64 bug

NAME
       ndctl-destroy-namespace - destroy the given namespace(s)


SYNOPSIS
       ndctl destroy-namespace <namespace> [<options>]


THEORY OF OPERATION
       The capacity of an NVDIMM REGION (contiguous span of persistent memory) is accessed via one or more
       NAMESPACE devices. REGION is the Linux term for what ACPI and UEFI call a DIMM-interleave-set, or a
       system-physical-address-range that is striped (by the memory controller) across one or more memory
       modules.

       The UEFI specification defines the NVDIMM Label Protocol as the combination of label area access methods
       and a data format for provisioning one or more NAMESPACE objects from a REGION. Note that label support
       is optional and if Linux does not detect the label capability it will automatically instantiate a
       "label-less" namespace per region. Examples of label-less namespaces are the ones created by the kernel’s
       memmap=ss!nn command line option (see the nvdimm wiki on kernel.org), or NVDIMMs without a valid
       namespace index in their label area.

       A namespace can be provisioned to operate in one of 4 modes, fsdax, devdax, sector, and raw. Here are the
       expected usage models for these modes: - fsdax: Filesystem-DAX mode is the default mode of a namespace
       when specifying ndctl create-namespace with no options. It creates a block device (/dev/pmemX[.Y]) that
       supports the DAX capabilities of Linux filesystems (xfs and ext4 to date). DAX removes the page cache
       from the I/O path and allows mmap(2) to establish direct mappings to persistent memory media. The DAX
       capability enables workloads / working-sets that would exceed the capacity of the page cache to scale up
       to the capacity of persistent memory. Workloads that fit in page cache or perform bulk data transfers may
       not see benefit from DAX. When in doubt, pick this mode.

       •   devdax: Device-DAX mode enables similar mmap(2) DAX mapping capabilities as Filesystem-DAX. However,
           instead of a block-device that can support a DAX-enabled filesystem, this mode emits a single
           character device file (/dev/daxX.Y). Use this mode to assign persistent memory to a virtual-machine,
           register persistent memory for RDMA, or when gigantic mappings are needed.

       •   sector: Use this mode to host legacy filesystems that do not checksum metadata or applications that
           are not prepared for torn sectors after a crash. Expected usage for this mode is for small boot
           volumes. This mode is compatible with other operating systems.

       •   raw: Raw mode is effectively just a memory disk that does not support DAX. Typically this indicates a
           namespace that was created by tooling or another operating system that did not know how to create a
           Linux fsdax or devdax mode namespace. This mode is compatible with other operating systems, but
           again, does not support DAX operation.


OPTIONS
       <namespace>
           A namespaceX.Y device name. The keyword all can be specified to carry out the operation on every
           namespace in the system, optionally filtered by region (see --region=option)

       -r, --region=

               A 'regionX' device name, or a region id number. The keyword 'all' can
               be specified to carry out the operation on every region in the system,
               optionally filtered by bus id (see --bus= option).

       -b, --bus=
           Enforce that the operation only be carried on devices that are attached to the given bus. Where bus
           can be a provider name or a bus id number.

       -v, --verbose
           Emit debug messages for the namespace operation

       -f, --force
           Unless this option is specified the destroy namespace operation will fail if the namespace is
           presently active. Specifying --force causes the namespace to be disabled before the operation is
           attempted. However, if the namespace is mounted then the disable namespace and destroy namespace
           operations will be aborted. The namespace must be unmounted before being destroyed.


       Copyright (c) 2016 - 2018, Intel Corporation. License GPLv2: GNU GPL version 2
       http://gnu.org/licenses/gpl.html. This is free software: you are free to change and redistribute it.
       There is NO WARRANTY, to the extent permitted by law.


SEE ALSO
       ndctl-create-namespace(1)