=========================================================
ϡ
Linux-3.4.1/Documentation/filesystems/ceph.txt Ǥ
Ρ JF ץ < http://www.linux.or.jp/JF/ >
  2012/6/13
  Seiji Kaneko < skaneko at mbn dot or dot jp >
=========================================================
#Ceph Distributed File System
#============================
Ceph ʬե륷ƥ
=========================

#Ceph is a distributed network file system designed to provide good
#performance, reliability, and scalability.
Ceph ɹǽĥɵᤷ߷פ줿ʬͥåȥե
륷ƥǤ

#Basic features include:
ʲδܵǽ󶡤Ƥޤ

# * POSIX semantics
# * Seamless scaling from 1 to many thousands of nodes
# * High availability and reliability.  No single point of failure.
# * N-way replication of data across storage nodes
# * Fast recovery from node failures
# * Automatic rebalancing of data on node addition/removal
# * Easy deployment: most FS components are userspace daemons
 * POSIX ߴ
 * 1 ΥΡɤޤǥ쥹˳ĥǽ
 * ѡ⿮ñξӽ
 * ȥ졼Ρɴ֤Ǥ N-way ʣǽ
 * Ρɸξ㤫®䤫ʲ
 * ΡɲáФǡμưƥХ
 * ưפʥΡŸ: ؤɤ FS ݡͥȤϥ桼֤ưǡ
   
 
#Also,
# * Flexible snapshots (on any directory)
# * Recursive accounting (nested files, directories, bytes)
ޤ
 * ʥʥåץå (ɤΥǥ쥯ȥǤ)
 * Ƶƥ (ե롢ǥ쥯ȥꡢХȥǡΥͥ)

#In contrast to cluster filesystems like GFS, OCFS2, and GPFS that rely
#on symmetric access by all clients to shared block devices, Ceph
#separates data and metadata management into independent server
#clusters, similar to Lustre.  Unlike Lustre, however, metadata and
#storage nodes run entirely as user space daemons.  Storage nodes
#utilize btrfs to store data objects, leveraging its advanced features
#(checksumming, metadata replication, etc.).  File data is striped
#across storage nodes in large chunks to distribute workload and
#facilitate high throughputs.  When storage nodes fail, data is
#re-replicated in a distributed fashion by the storage nodes themselves
#(with some minimal coordination from a cluster monitor), making the
#system extremely efficient and scalable.
GFSOCFS2  GPFS ʤɤΥ饹ե륷ƥϡƥ饤
ζ֥ͭåǥХؤоΤʥȤƤޤCeph 
 Lustre Ȼǡȥ᥿ǡʬΥΩΥХ饹
ΤäƤޤLustre Ȥϰäƥ᥿ǡȥȥ졼
ɤϴ˥桼֥ǡޤȥ졼Ρɤϥǡ
ȤγǼ btrfs Ȥäơʵǽ (åࡢ᥿ǡ
ץꥱ) ѤƤޤեǡϡ礭ʥñ
ǥȥ졼Ρɴ֤ǥȥ饤פ졢٤ʬƹ⤤롼ץåȤ
¸ƤޤĤΥȥ졼Ρɤξ㤷硢饹˥
Ǿ¤βǡȥ졼ΡɴּȤǥǡΥץꥱ
Ƽ¹Ԥ뤿ᡢƥ϶ˤƸΨŪǳĥ٤ΤȤʤäƤ
ޤ

#Metadata servers effectively form a large, consistent, distributed
#in-memory cache above the file namespace that is extremely scalable,
#dynamically redistributes metadata in response to workload changes,
#and can tolerate arbitrary (well, non-Byzantine) node failures.  The
#metadata server takes a somewhat unconventional approach to metadata
#storage to significantly improve performance for common workloads.  In
#particular, inodes with only a single link are embedded in
#directories, allowing entire directories of dentries and inodes to be
#loaded into its cache with a single I/O operation.  The contents of
#extremely large directories can be fragmented and managed by
#independent metadata servers, allowing scalable concurrent access.
᥿ǡФϡ¸ŪˤϾ嵭Υե֤̾Ф롢
κΤ줿ʬꥭåޤΥ᥿ǡ
϶ˤƳĥ⤯٤ưȼäưŪ˥᥿ǡ֤
(ޤäˤޤǤʤ) ǤդΥΡɤθξѤ褦ˤʤ
Ƥޤ
᥿ǡФǤϡŪ٤Ǥǽ礭夹뤿ᡢ᥿
ȥ졼ȤƤϤŪǤϤʤˡΤäƤޤäˡ
ΰĤʤ inode ϥǥ쥯ȥޤ졢dentry  inode 
ǥ쥯ȥΤĤ I/O ǥå˼褦ˤƤ
ޤˤƵʥǥ쥯ȥƤʣΩʥ᥿ǡФʬ
䤵ƴ뤿ᡢĥͥ줿¹ԥǽˤʤäƤޤ

#The system offers automatic data rebalancing/migration when scaling
#from a small cluster of just a few nodes to many hundreds, without
#requiring an administrator carve the data set into static volumes or
#go through the tedious process of migrating data between servers.
#When the file system approaches full, new nodes can be easily added
#and things will "just work."
ƥǤϡԤΥǡåȻʤΡ (Ρ) 饹
ɴޤǤγĥԤäΡưǡƥХ/ޥ졼
ǽ󶡤ƤޤԤϸꥵΥܥ塼˥ǡåȤ
ꡢд֤ǥǡΰưԤäȤ
ޤե륷ƥबդˤʤĤĤ硢Ρɤñ
ɲä¨ưפǽȤƤޤ

#Ceph includes flexible snapshot mechanism that allows a user to create
#a snapshot on any subdirectory (and its nested contents) in the
#system.  Snapshot creation and deletion are as simple as 'mkdir
#.snap/foo' and 'rmdir .snap/foo'.
Ceph ˤϽʥʥåץåȵǽ󶡤Ƥơ桼ϥƥ
ǤդΥ֥ǥ쥯ȥ (ӥͥȤ줿ƥ) Υʥåץ
åȤǽǤʥåץåȤκȺϡ'mkdir .snap/foo' 
 'rmdir .snap/foo' ԤδñǤ

#Ceph also provides some recursive accounting on directories for nested
#files and bytes.  That is, a 'getfattr -d foo' on any directory in the
#system will reveal the total number of nested regular files and
#subdirectories, and a summation of all nested file sizes.  This makes
#the identification of large disk space consumers relatively quick, as
#no 'du' or similar recursive scan of the file system is required.
ˡCeph ǤϥͥȤ줿ǥ쥯ȥǡФƵŪ
ƥ󥰵ǽ󶡤ƤޤŪˤϡƥΤɤΥǥ쥯
ǤǤ 'getfattr -d foo' ¹ԤСͥȤ줿̾Υեȥ
֥ǥ쥯ȥͥȤ줿ե륵ιפޤ
ꡢdu ʤɤΥե륷ƥκƵɬפȤˡ¿
Υǥ񤷤ƤȿͤŪ®ŦȯǤޤ


#Mount Syntax
#============
ޥȤν
==============

#The basic mount syntax is:
ŪʥޥȤν񼰤ϰʲΤȤǤ

 # mount -t ceph monip[:port][,monip2[:port]...]:/[subdir] mnt

#You only need to specify a single monitor, as the client will get the
#full list when it connects.  (However, if the monitor you specify
#happens to be down, the mount won't succeed.)  The port can be left
#off if the monitor is using the default.  So if the monitor is at
#1.2.3.4,
İʾΥ˥ꤹɬפϤޤ󡣥饤Ȥ³˥
ΤΥꥹȤ뤿Ǥâꤷ˥
Ƥ硢ޥȤϼԤޤݡȤϡ˥ͤѤƤ
硢ꤹɬפϤޤ󡣤ޤȤȡ˥ 1.2.3.4 ˤ
硢ʲλǽʬȤʤޤ

 # mount -t ceph 1.2.3.4:/ /mnt/ceph

#is sufficient.  If /sbin/mount.ceph is installed, a hostname can be
#used instead of an IP address.
/sbin/mount.ceph 󥹥ȡ뤵Ƥʤ顢IP ɥ쥹˥
̾Ȥޤ


#Mount Options
#=============
ޥȥץ
==================

  ip=A.B.C.D[:N]
#	Specify the IP and/or port the client should bind to locally.
#	There is normally not much reason to do this.  If the IP is not
#	specified, the client's IP address is determined by looking at the
#	address its connection to the monitor originates from.
	饤Ȥꤹ٤ IP /ޤ ݡȤ
	ꤷޤ̾ϤԤͳϤޤꤢޤIP ֹ椬
	ꤵƤʤ硢饤Ȥ IP ɥ쥹ϥ˥ؤ³
	Ԥä³ɥ쥹Ĵ٤뤳ȤǷꤵޤ

  wsize=X
#	Specify the maximum write size in bytes.  By default there is no
#	maximum.  Ceph will normally size writes based on the file stripe
#	size.
	񤭹ΥХȿꤷޤͤȤƤϡ
	¤ϤޤCeph ̾ϥե륹ȥ饤ץ
	񤭹ߤԤޤ

  rsize=X
#	Specify the maximum readahead.
	ɤߤκĹꤷޤ

  mount_timeout=X
#	Specify the timeout value for mount (in seconds), in the case
#	of a non-responsive Ceph file system.  The default is 30
#	seconds.
	Ceph ե륷ƥबʤ硢ޥȻΥॢ
	Ȼ֤äǻꤷޤͤ 30 äǤ

  rbytes
#	When stat() is called on a directory, set st_size to 'rbytes',
#	the summation of file sizes over all files nested beneath that
#	directory.  This is the default.
	stat() ǥ쥯ȥФƸƤФ줿硢st_size  rbytes
	Ĥޤǥ쥯ȥʲ˥ͥȤƤե륵ι
	ޤ줬ͤǤ

  norbytes
#	When stat() is called on a directory, set st_size to the
#	number of entries in that directory.
	stat() ǥ쥯ȥФƸƤФ줿硢st_size ˥ǥ쥯
	ȥΥȥޤ

  nocrc
#	Disable CRC32C calculation for data writes.  If set, the storage node
#	must rely on TCP's error correction to detect data corruption
#	in the data payload.
	ǡ񤭹߻ CRC32C ׻Ԥޤ󡣤Υե饰å
	Ƥ硢ȥ졼ΡɤΥǡڥɤ˲Ф
	TCP Υ顼ǽ˰¸ޤ

  dcache
#        Use the dcache contents to perform negative lookups and
#        readdir when the client has the entire directory contents in
#        its cache.  (This does not change correctness; the client uses
#        cached metadata only when a lease or capability ensures it is
#        valid.)
	饤¦ǥǥ쥯ȥΤ򥭥å夷Ƥ硢
	readdir ꥯȽԤݤȡեåå (negative lookup)
	κݤˡdcache åѤޤ (ϥե륷ƥ
	ˤϱƶޤ󡣥饤Ȥϡ꡼ޤϥѥӥƥ
	äƥå夵줿᥿ǡͭǤ뤳ȤݾڤƤ
	ˤΤߡå夵줿ǡѤ뤫Ǥ)

  nodcache
#        Do not use the dcache as above.  This avoids a significant amount of
#        complex code, sacrificing performance without affecting correctness,
#        and is useful for tracking down bugs.
	嵭Τ褦 dcache ѤԤʤʤλǤϡե
	˱ƶ뤳ȤʤǽˤʣʥɤΤʤʬμ
	Ԥ򤷤ޤХפκݤͭѤǤ

  noasyncreaddir
#	Do not use the dcache as above for readdir.
	readdir Фơ嵭Τ褦 dcache ѤԤʤޤ


#More Information
#================
ɲþ
========

#For more information on Ceph, see the home page at
#	http://ceph.newdream.net/wiki
Ceph ˤĤƤäΤꤿϡʲΥۡڡ
	http://ceph.newdream.net/wiki

#The Linux kernel client source tree is available at
#	git://ceph.newdream.net/git/ceph-client.git
#	git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client.git
Linux ͥΥ饤ȥĥ꡼ϰʲ󶡤Ƥޤ
	git://ceph.newdream.net/git/ceph-client.git
	git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client.git

#and the source for the full system is at
#	git://ceph.newdream.net/git/ceph.git
ƥΤΥϰʲ󶡤Ƥޤ
	git://ceph.newdream.net/git/ceph.git

