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Chapter 20. Extended Attributes

Extended Attributes (XATTRs) are an important aspect in your configuration. Some file systems have limits on the number of bytes stored in XATTRS. Additionally, in some cases, the filesystem may not be as fast as an alternative method of storing XATTRs. The following settings may help improve performance by using a method of storing XATTRs that is extrinsic to the underlying filesystem.

Ceph XATTRs are stored as inline xattr, using the XATTRs provided by the underlying file system, if it does not impose a size limit. If there is a size limit ( 4KB total on ext4, for instance ), some Ceph XATTRs will be stored in an key/value database ( aka omap ) when the filestore max inline xattr size or filestore max inline xattrs threshold are reached.

filestore_xattr_use_omap

Description
Use object map for XATTRS. Set to true for ext4 file systems.
Type
Boolean
Required
No
Default
false

filestore_omap_header_cache_size

Description
Determines the size of the LRU used to cache object omap headers. Larger values use more memory but may reduce lookups on omap. (Experts only).
Type
Integer
Default
1024

filestore_omap_backend

Description
Used to determine which backend is used for the omap. Can be set to "leveldb" or "rocksdb". (Experts only. rocksdb is experimental.)
Type
String
Default
"leveldb"

filestore_debug_omap_check

Description
Debugging check on synchronization. Expensive. For debugging only.
Type
Boolean
Required
No
Default
0

filestore_max_inline_xattr_size

Description
The maximimum size of an XATTR stored in the filesystem (i.e., XFS, btrfs, ext4, etc.) per object. Should not be larger than the filesytem can handle.
Type
Unsigned 32-bit Integer
Required
No
Default
512

filestore_max_inline_xattrs

Description
The maximum number of XATTRs stored in the fileystem per object.
Type
32-bit Integer
Required
No
Default
2

filestore_max_inline_xattr_size_xfs

Description
The maximimum size of an XATTR stored in the filesystem for XFS filesystems per object. Should not be larger than the filesytem can handle.
Type
Unsigned 32-bit Integer
Default
65536

filestore_max_inline_xattr_size_btrfs

Description
The maximimum size of an XATTR stored in the filesystem for btrfs per object. Should not be larger than the filesytem can handle.
Type
Unsigned 32-bit Integer
Default
2048

filestore_max_inline_xattr_size_other

Description
The maximimum size of an XATTR stored in the filesystem for filesystems other than btrfs or XFS (i.e., ext3, ext4, etc.) per object. Should not be larger than the filesystem can handle.
Type
Unsigned 32-bit Integer
Default
512

filestore_max_inline_xattrs

Description
The maximum number of XATTRs stored in the fileystem per object. Overrides fine-grained settings.
Type
Unsigned 32-bit Integer
Default
0

filestore_max_inline_xattrs_xfs

Description
The maximum number of XATTRs stored in an XFS fileystem per object.
Type
Unsigned 32-bit Integer
Default
10

filestore_max_inline_xattrs_btrfs

Description
The maximum number of XATTRs stored in a btrfs fileystem per object.
Type
Unsigned 32-bit Integer
Default
10

filestore_max_inline_xattrs_other

Description
The maximum number of XATTRs stored in filesystems other than btrfs or XFS (i.e., ext3, ext4, etc.) per object.
Type
Unsigned 32-bit Integer
Default
2
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