Difference between revisions of "Frequently Asked Questions"

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(→‎What do all these acronyms mean?: add SEQ and OID, order FID alphabetically)
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=== What do all these acronyms mean? ===
 
=== What do all these acronyms mean? ===
 
* '''DNE''' - '''D'''istributed '''N'''amespace '''E'''nvironment - feature aggregating multiple MDTs (possibly on multiple MDSes) into a single filesystem namespace
 
* '''DNE''' - '''D'''istributed '''N'''amespace '''E'''nvironment - feature aggregating multiple MDTs (possibly on multiple MDSes) into a single filesystem namespace
 +
* '''FID''' - '''F'''ile '''ID'''entifier - unique 128-bit identifier for every object within a single filesystem, made up of a 64-bit sequence (SEQ), a 32-bit object ID (OID), and a 32-bit version field
 
* '''IDIF''' - OST object '''ID''' '''I'''n '''F'''ID - specific FID range reserved for compatibility with pre-DNE OST objects
 
* '''IDIF''' - OST object '''ID''' '''I'''n '''F'''ID - specific FID range reserved for compatibility with pre-DNE OST objects
 
* '''IGIF''' - '''I'''node and '''G'''eneration '''I'''n '''F'''ID - specific FID range reserved for compatibility from Lustre 1.x MDT inode objects
 
* '''IGIF''' - '''I'''node and '''G'''eneration '''I'''n '''F'''ID - specific FID range reserved for compatibility from Lustre 1.x MDT inode objects
* '''FID''' - '''F'''ile '''ID'''entifier - unique 128-bit identifier for every object within a single filesystem, made up of a 64-bit sequence, a 32-bit object ID, and a 32-bit version field
 
 
* '''IOV''' - '''I'''/'''O''' '''V'''ector
 
* '''IOV''' - '''I'''/'''O''' '''V'''ector
 
* '''LMV''' - '''L'''ogical '''M'''etadata '''V'''olume - client software layer that handles client (llite) access to multiple MDTs
 
* '''LMV''' - '''L'''ogical '''M'''etadata '''V'''olume - client software layer that handles client (llite) access to multiple MDTs
* '''LNET''' - '''L'''ustre '''Net'''work - Type agnostic networking layer (TCP/IP on Ethernet, InfiniBand, Omni-Path, Cray Gemini, etc.)
+
* '''LNet''' - '''L'''ustre '''Net'''work - Type-agnostic networking layer (TCP/IP on Ethernet, InfiniBand, Omni-Path, Cray Gemini, etc.)
 
* '''LOD''' - '''L'''ogical '''O'''bject '''D'''evice - MDS software layer that handles access to multiple MDTs and multiple OSTs
 
* '''LOD''' - '''L'''ogical '''O'''bject '''D'''evice - MDS software layer that handles access to multiple MDTs and multiple OSTs
 
* '''LOV''' - '''L'''ogical '''O'''bject '''V'''olume - client software layer that handles client (llite) access to multiple OSTs
 
* '''LOV''' - '''L'''ogical '''O'''bject '''V'''olume - client software layer that handles client (llite) access to multiple OSTs
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* '''NID''' -  '''N'''etwork '''Id'''entifier - used to uniquely identify a Lustre network endpoint by node ID and network type.
 
* '''NID''' -  '''N'''etwork '''Id'''entifier - used to uniquely identify a Lustre network endpoint by node ID and network type.
 
* '''OFD''' - '''O'''bject '''F'''ilter '''D'''evice - OSS software layer that handles file IO
 
* '''OFD''' - '''O'''bject '''F'''ilter '''D'''evice - OSS software layer that handles file IO
 +
* '''OID''' - '''O'''bject '''ID'''entifier - the sub-range of a FID that is allocated by a client within a SEQuence to identify an object
 
* '''OSC''' - '''O'''bject '''S'''torage '''C'''lient - client software layer that interfaces to the OST
 
* '''OSC''' - '''O'''bject '''S'''torage '''C'''lient - client software layer that interfaces to the OST
 
* '''OSD''' - '''O'''bject '''S'''torage '''D'''evice - server software layer that abstracts MDD and OFD access to underlying disk filesystems like ldiskfs and ZFS
 
* '''OSD''' - '''O'''bject '''S'''torage '''D'''evice - server software layer that abstracts MDD and OFD access to underlying disk filesystems like ldiskfs and ZFS
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* '''OST''' - '''O'''bject '''S'''torage '''T'''arget - storage device that holds the filesystem data (regular data files, not directories, xattrs, or other metadata)
 
* '''OST''' - '''O'''bject '''S'''torage '''T'''arget - storage device that holds the filesystem data (regular data files, not directories, xattrs, or other metadata)
 
* '''PTLRPC''' - '''P'''or'''t'''a'''l''' '''RPC''' -  A remote procedure call protocol layered over LNET
 
* '''PTLRPC''' - '''P'''or'''t'''a'''l''' '''RPC''' -  A remote procedure call protocol layered over LNET
 +
* '''SEQ''' - '''SEQ'''uence number of FIDs that are allocated to a client or server for its own exclusive use.  The SEQ controller on MDT0000 manages the entire 64-bit SEQ space, and grants large sub-ranges to MDTs and OSTs, which may in turn grant sub-sub-ranges to individual clients.
  
 
== Releases ==
 
== Releases ==

Revision as of 13:27, 4 May 2020

Welcome to the Lustre FAQ!

General

What is Lustre?

Lustre is a scale-out architecture distributed parallel filesystem. Metadata services and storage are segregated from data services and storage.

What is the difference between a server (MDS/OSS) and a target (MDT/OST)?

A target is the storage device where object (file) or metadata is kept. The servers service request from clients on their behalf. Clients do not access storage directly.

Why does lists.lustre.org say "The list overview page has been disabled temporarily"?

The mailing lists at lists.lustre.org are running on a fully vendor managed solution at DreamHost. Unfortunately, they have disabled the list overview page for all of their customers, and they have no definitive plan to correct that in the near future. "Temporarily" apparently really means "permanently". While this is unfortunate, DreamHost's mailing list servers are pleasantly fast, low in maintenance, and low in cost. We will just need to live with this minor inconvenience. In the mean time, you can get a full list of mailing lists from Mailing Lists and IRC.

Acronyms

What do all these acronyms mean?

  • DNE - Distributed Namespace Environment - feature aggregating multiple MDTs (possibly on multiple MDSes) into a single filesystem namespace
  • FID - File IDentifier - unique 128-bit identifier for every object within a single filesystem, made up of a 64-bit sequence (SEQ), a 32-bit object ID (OID), and a 32-bit version field
  • IDIF - OST object ID In FID - specific FID range reserved for compatibility with pre-DNE OST objects
  • IGIF - Inode and Generation In FID - specific FID range reserved for compatibility from Lustre 1.x MDT inode objects
  • IOV - I/O Vector
  • LMV - Logical Metadata Volume - client software layer that handles client (llite) access to multiple MDTs
  • LNet - Lustre Network - Type-agnostic networking layer (TCP/IP on Ethernet, InfiniBand, Omni-Path, Cray Gemini, etc.)
  • LOD - Logical Object Device - MDS software layer that handles access to multiple MDTs and multiple OSTs
  • LOV - Logical Object Volume - client software layer that handles client (llite) access to multiple OSTs
  • MDC - MetaData Client - client software layer that interfaces to the MDS
  • MDD - Metadata Device Driver - MDS software layer that understands POSIX semantics for file access
  • MDS - MetaData Server - software service that manages access to filesystem namespace (inodes, paths, permission) requests from the client.
  • MDT - MetaData Target - storage device that holds the filesystem metadata (attributes, inodes, directories, xattrs, etc)
  • MGS - ManaGement Server - service that helps clients and servers with configuration
  • MGT - ManaGement Target - storage device that holds the configuration logs
  • NID - Network Identifier - used to uniquely identify a Lustre network endpoint by node ID and network type.
  • OFD - Object Filter Device - OSS software layer that handles file IO
  • OID - Object IDentifier - the sub-range of a FID that is allocated by a client within a SEQuence to identify an object
  • OSC - Object Storage Client - client software layer that interfaces to the OST
  • OSD - Object Storage Device - server software layer that abstracts MDD and OFD access to underlying disk filesystems like ldiskfs and ZFS
  • OSP - Object Storage Proxy - server software layer that interfaces from one MDS to the OSD on another MDS or another OSS
  • OSS - Object Storage Server - software service that manages access to filesystem data (read, write, truncate, etc)
  • OST - Object Storage Target - storage device that holds the filesystem data (regular data files, not directories, xattrs, or other metadata)
  • PTLRPC - Portal RPC - A remote procedure call protocol layered over LNET
  • SEQ - SEQuence number of FIDs that are allocated to a client or server for its own exclusive use. The SEQ controller on MDT0000 manages the entire 64-bit SEQ space, and grants large sub-ranges to MDTs and OSTs, which may in turn grant sub-sub-ranges to individual clients.

Releases

When is the next Major release?

We plan to tag and build Major releases of Lustre about every six months, the roadmap gives a high level idea of the current expectations

When is the next Maintenance Release?

There are multiple maintenance relesases per year but the exact timing can depend upon several factors (Linux distro releases, OpenZFS releases, important bugfixes). The Lustre Working Group is the best source of information about the latest status