lvmd-protocol.md

Protocol Documentation

Table of Contents

• lvmd/proto/lvmd.proto

  • CreateLVRequest

  • CreateLVResponse

  • Empty

  • GetFreeBytesRequest

  • GetFreeBytesResponse

  • GetLVListRequest

  • GetLVListResponse

  • LogicalVolume

  • RemoveLVRequest

  • ResizeLVRequest

  • WatchItem

  • WatchResponse

  • LVService

  • VGService

• Scalar Value Types

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lvmd/proto/lvmd.proto

LVMd manages logical volumes of an LVM volume group.

The protocol consists of two services:

• VGService provides information of the volume group.
• LVService provides management functions for logical volumes on the volume group.

CreateLVRequest

Represents the input for CreateLV.

Field	Type	Label	Description
name	string		The logical volume name.
size_gb	uint64		Volume size in GiB.
tags	string	repeated	Tags to add to the volume during creation
device_class	string

CreateLVResponse

Represents the response of CreateLV.

Field	Type	Label	Description
volume	LogicalVolume		Information of the created volume.

Empty

GetFreeBytesRequest

Field	Type	Label	Description
device_class	string

GetFreeBytesResponse

Represents the response of GetFreeBytes.

Field	Type	Label	Description
free_bytes	uint64		Free space of the volume group in bytes.

GetLVListRequest

Field	Type	Label	Description
device_class	string

GetLVListResponse

Represents the response of GetLVList.

Field	Type	Label	Description
volumes	LogicalVolume	repeated	Information of volumes.

LogicalVolume

Represents a logical volume.

Field	Type	Label	Description
name	string		The logical volume name.
size_gb	uint64		Volume size in GiB.
dev_major	uint32		Device major number.
dev_minor	uint32		Device minor number.
tags	string	repeated	Tags to add to the volume during creation

RemoveLVRequest

Represents the input for RemoveLV.

Field	Type	Label	Description
name	string		The logical volume name.
device_class	string

ResizeLVRequest

Represents the input for ResizeLV.

The volume must already exist. The volume size will be set to exactly "size_gb".

Field	Type	Label	Description
name	string		The logical volume name.
size_gb	uint64		Volume size in GiB.
device_class	string

WatchItem

Field	Type	Label	Description
free_bytes	uint64		Free space of the volume group in bytes.
device_class	string

WatchResponse

Represents the stream output from Watch.

Field	Type	Label	Description
free_bytes	uint64		Free space of the default volume group in bytes.
items	WatchItem	repeated

LVService

Service to manage logical volumes of the volume group.

Method Name	Request Type	Response Type	Description
CreateLV	CreateLVRequest	CreateLVResponse	Create a logical volume.
RemoveLV	RemoveLVRequest	Empty	Remove a logical volume.
ResizeLV	ResizeLVRequest	Empty	Resize a logical volume.

VGService

Service to retrieve information of the volume group.

Method Name	Request Type	Response Type	Description
GetLVList	GetLVListRequest	GetLVListResponse	Get the list of logical volumes in the volume group.
GetFreeBytes	GetFreeBytesRequest	GetFreeBytesResponse	Get the free space of the volume group in bytes.
Watch	Empty	WatchResponse stream	Stream the volume group metrics.

Scalar Value Types

.proto Type	Notes	C++	Java	Python	Go	C#	PHP	Ruby
double		double	double	float	float64	double	float	Float
float		float	float	float	float32	float	float	Float
int32	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint32 instead.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
int64	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint64 instead.	int64	long	int/long	int64	long	integer/string	Bignum
uint32	Uses variable-length encoding.	uint32	int	int/long	uint32	uint	integer	Bignum or Fixnum (as required)
uint64	Uses variable-length encoding.	uint64	long	int/long	uint64	ulong	integer/string	Bignum or Fixnum (as required)
sint32	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int32s.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
sint64	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int64s.	int64	long	int/long	int64	long	integer/string	Bignum
fixed32	Always four bytes. More efficient than uint32 if values are often greater than 2^28.	uint32	int	int	uint32	uint	integer	Bignum or Fixnum (as required)
fixed64	Always eight bytes. More efficient than uint64 if values are often greater than 2^56.	uint64	long	int/long	uint64	ulong	integer/string	Bignum
sfixed32	Always four bytes.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
sfixed64	Always eight bytes.	int64	long	int/long	int64	long	integer/string	Bignum
bool		bool	boolean	boolean	bool	bool	boolean	TrueClass/FalseClass
string	A string must always contain UTF-8 encoded or 7-bit ASCII text.	string	String	str/unicode	string	string	string	String (UTF-8)
bytes	May contain any arbitrary sequence of bytes.	string	ByteString	str	[]byte	ByteString	string	String (ASCII-8BIT)