* [ndctl PATCH v2] Documentation/namespace-description: Clarify label-less restrictions
@ 2019-08-08 17:57 Vishal Verma
2019-08-08 18:13 ` Jeff Moyer
0 siblings, 1 reply; 2+ messages in thread
From: Vishal Verma @ 2019-08-08 17:57 UTC (permalink / raw)
To: linux-nvdimm
In the ndctl-create-namespace (and related) man pages, add a
clarification note regarding some of the restrictions a user may see
when operating on label-less namespaces.
Link: https://github.com/pmem/ndctl/issues/52
Reported-by: Jane Chu <jane.chu@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
v2:
- Remove the part about an address abstraction mechanism; It didn't add
any value (Jeff)
- Add an additional sentence about space reclamation semantics (Dan)
Documentation/ndctl/namespace-description.txt | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/Documentation/ndctl/namespace-description.txt b/Documentation/ndctl/namespace-description.txt
index 94999e5..c59fbef 100644
--- a/Documentation/ndctl/namespace-description.txt
+++ b/Documentation/ndctl/namespace-description.txt
@@ -18,6 +18,15 @@ 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.
+NOTE: Label-less namespaces lack many of the features of their label-rich
+cousins. For example, their size cannot be modified, or they cannot be
+fully 'destroyed' (i.e. the space reclaimed). A destroy operation will
+zero any mode-specific metadata. Finally, for create-namespace operations
+on label-less namespaces, ndctl bypasses the region capacity availability
+checks, and always satisfies the request using the full region capacity.
+The only reconfiguration operation supported on a label-less namespace
+is changing its 'mode'.
+
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:
--
2.20.1
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Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [ndctl PATCH v2] Documentation/namespace-description: Clarify label-less restrictions
2019-08-08 17:57 [ndctl PATCH v2] Documentation/namespace-description: Clarify label-less restrictions Vishal Verma
@ 2019-08-08 18:13 ` Jeff Moyer
0 siblings, 0 replies; 2+ messages in thread
From: Jeff Moyer @ 2019-08-08 18:13 UTC (permalink / raw)
To: Vishal Verma; +Cc: linux-nvdimm
Vishal Verma <vishal.l.verma@intel.com> writes:
> In the ndctl-create-namespace (and related) man pages, add a
> clarification note regarding some of the restrictions a user may see
> when operating on label-less namespaces.
>
> Link: https://github.com/pmem/ndctl/issues/52
> Reported-by: Jane Chu <jane.chu@oracle.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
>
> v2:
> - Remove the part about an address abstraction mechanism; It didn't add
> any value (Jeff)
> - Add an additional sentence about space reclamation semantics (Dan)
LGTM
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
-Jeff
>
> Documentation/ndctl/namespace-description.txt | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/Documentation/ndctl/namespace-description.txt b/Documentation/ndctl/namespace-description.txt
> index 94999e5..c59fbef 100644
> --- a/Documentation/ndctl/namespace-description.txt
> +++ b/Documentation/ndctl/namespace-description.txt
> @@ -18,6 +18,15 @@ 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.
>
> +NOTE: Label-less namespaces lack many of the features of their label-rich
> +cousins. For example, their size cannot be modified, or they cannot be
> +fully 'destroyed' (i.e. the space reclaimed). A destroy operation will
> +zero any mode-specific metadata. Finally, for create-namespace operations
> +on label-less namespaces, ndctl bypasses the region capacity availability
> +checks, and always satisfies the request using the full region capacity.
> +The only reconfiguration operation supported on a label-less namespace
> +is changing its 'mode'.
> +
> 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:
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
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