Lustre 1.6 Operations Manual

Completion Callback
Configlog
Configuration Lock
An RPC made by an OST or MDT to another system, usually a client, to
indicate that the lock request is now granted.
An llog file used in a node, or retrieved from a management server over the
network with configuration instructions for Lustre systems at startup time.
A lock held by every node in the cluster to control configuration changes.
When callbacks are received, the nodes quiesce their traffic, cancel the lock and
await configuration changes after which they reacquire the lock before
resuming normal operation.
D
Default stripe pattern
Direct I/O
Directory stripe
descriptor
Information in the LOV descriptor that describes the default stripe count used
for new files in a file system. This can be amended by using a directory stripe
descriptor or a per-file stripe descriptor.
A mechanism which can be used during read and write system calls. It
bypasses the kernel. I/O cache to memory copy of data between kernel and
application memory address spaces.
An extended attribute that describes the default stripe pattern for files
underneath that directory.
E
EA
Eviction
Export
Extent Lock
Extended Attribute. A small amount of data which can be retrieved through a
name associated with a particular inode. Lustre uses EAa to store striping
information (location of file data on OSTs). Examples of extended attributes are
ACLs, striping information, and crypto keys.
The process of eliminating server state for a client that is not returning to the
cluster after a timeout or if server failures have occurred.
The state held by a server for a client that is sufficient to transparently recover
all in-flight operations when a single failure occurs.
A lock used by the OSC to protect an extent in a storage object for concurrent
control of read/write, file size acquisition and truncation operations.
Glossary-2 Lustre 1.6 Operations Manual • September 2008