glusterfs架构和基本概念

	//dht卷的第一个brick，client1
	volume dht_vol-client-0
	    type protocol/client
	    option ping-timeout 42
	    option remote-host 10.211.55.3
	    option remote-subvolume /glusterfs/dht/brick1
	    option transport-type socket
	    option transport.address-family inet
	    option username dc7532ac-03fa-4888-b092-248ea57aa5db
	    option password 29b86bb2-d1f4-4262-be52-5e5edff25374
	    option transport.socket.ssl-enabled off
	    option transport.tcp-user-timeout 0
	    option transport.socket.keepalive-time 20
	    option transport.socket.keepalive-interval 2
	    option transport.socket.keepalive-count 9
	    option strict-locks off
	    option send-gids true
	end-volume
	//dht卷的第二个volume,client2
	volume dht_vol-client-1
	    type protocol/client
	    option ping-timeout 42
	    option remote-host 10.211.55.3
	    option remote-subvolume /glusterfs/dht/brick2
	    option transport-type socket
	    option transport.address-family inet
	    option username dc7532ac-03fa-4888-b092-248ea57aa5db
	    option password 29b86bb2-d1f4-4262-be52-5e5edff25374
	    option transport.socket.ssl-enabled off
	    option transport.tcp-user-timeout 0
	    option transport.socket.keepalive-time 20
	    option transport.socket.keepalive-interval 2
	    option transport.socket.keepalive-count 9
	    option strict-locks off
	    option send-gids true
	end-volume
 
	//dht,subvolume is dht_vol-client-0 dht_vol-client-1
	volume dht_vol-dht
	    type cluster/distribute
	    option lock-migration off
	    option force-migration off
	    subvolumes dht_vol-client-0 dht_vol-client-1
	end-volume
 
	//utime,subvolume is dht_vol-dht
	volume dht_vol-utime
	    type features/utime
	    option noatime on
	    subvolumes dht_vol-dht
	end-volume
 
	//write-behind,subvolume is dht_vol-utime
	volume dht_vol-write-behind
	    type performance/write-behind
	    subvolumes dht_vol-utime
	end-volume
 
	//readdir-ahead,subvolume is dht_vol-write-behind
	volume dht_vol-readdir-ahead
	    type performance/readdir-ahead
	    option parallel-readdir off
	    option rda-request-size 131072
	    option rda-cache-limit 10MB
	    subvolumes dht_vol-write-behind
	end-volume
 
	//open-behind,subvolume is dht_vol-readdir-ahead
	volume dht_vol-open-behind
	    type performance/open-behind
	    subvolumes dht_vol-readdir-ahead
	end-volume
 
	//quick-read,subvolume is dht_vol-open-behind
	volume dht_vol-quick-read
	    type performance/quick-read
	    subvolumes dht_vol-open-behind
	end-volume
 
	//md-cache,subvolume is dht_vol-quick-read 
 
	volume dht_vol-md-cache
	    type performance/md-cache
	    subvolumes dht_vol-quick-read
	end-volume


 
	//io-threads,subvolume is dht_vol-md-cache
	volume dht_vol-io-threads
	    type performance/io-threads
	    subvolumes dht_vol-md-cache
	end-volume
 
	//distribute,subvolume is dht_vol-io-threads
	volume dht_vol
	    type debug/io-stats
	    option log-level INFO
	    option threads 16
	    option latency-measurement off
	    option count-fop-hits off
	    option global-threading off
	    subvolumes dht_vol-io-threads
	end-volume
 
	//meta-autoload,subvolume is dht_vol
	volume meta-autoload
	    type meta
	    subvolumes dht_vol
	end-volume

 		/* WARNING: make sure the list is in order with FOP definition in
 		   `rpc/xdr/src/glusterfs-fops.x`.
 		   If it is not in order, mainly the metrics related feature would be broken */
 		struct xlator_fops {
 		    fop_stat_t stat;
 		    fop_readlink_t readlink;
 		    fop_mknod_t mknod;
 		    fop_mkdir_t mkdir;
 		    fop_unlink_t unlink;
 		    fop_rmdir_t rmdir;
 		    fop_symlink_t symlink;
 		    fop_rename_t rename;
 		    fop_link_t link;
 		    fop_truncate_t truncate;
 		    fop_open_t open;
 		    fop_readv_t readv;
 		    fop_writev_t writev;
 		    fop_statfs_t statfs;
 		    fop_flush_t flush;
 		    fop_fsync_t fsync;
 		    fop_setxattr_t setxattr;
 		    fop_getxattr_t getxattr;
 		    fop_removexattr_t removexattr;
 		    fop_opendir_t opendir;
 		    fop_fsyncdir_t fsyncdir;
 		    fop_access_t access;
 		    fop_create_t create;
 		    fop_ftruncate_t ftruncate;
 		    fop_fstat_t fstat;
 		    fop_lk_t lk;
 		    fop_lookup_t lookup;
 		    fop_readdir_t readdir;
 		    fop_inodelk_t inodelk;
 		    fop_finodelk_t finodelk;
 		    fop_entrylk_t entrylk;
 		    fop_fentrylk_t fentrylk;
 		    fop_xattrop_t xattrop;
 		    fop_fxattrop_t fxattrop;
 		    fop_fgetxattr_t fgetxattr;
 		    fop_fsetxattr_t fsetxattr;
 		    fop_rchecksum_t rchecksum;
 		    fop_setattr_t setattr;
 		    fop_fsetattr_t fsetattr;
 		    fop_readdirp_t readdirp;
 
 		    /* These 3 are required to keep the index same as GF_FOP_##FOP */
 		    void *forget_placeholder;
 		    void *release_placeholder;
 		    void *releasedir_placeholder;
 
 		    fop_getspec_t getspec;
 		    fop_fremovexattr_t fremovexattr;
 		    fop_fallocate_t fallocate;
 		    fop_discard_t discard;
 		    fop_zerofill_t zerofill;
 		    fop_ipc_t ipc;
 		    fop_seek_t seek;
 		    fop_lease_t lease;
 		    fop_compound_t compound;
 		    fop_getactivelk_t getactivelk;
 		    fop_setactivelk_t setactivelk;
 		    fop_put_t put;
 		    fop_icreate_t icreate;
 		    fop_namelink_t namelink;
 		    fop_copy_file_range_t copy_file_range;
 
 		    /* these entries are used for a typechecking hack in STACK_WIND _only_ */
 		    /* make sure to add _cbk variables only after defining regular fops as
 		       its relative position is used to get the index */
 		    fop_stat_cbk_t stat_cbk;
 		    fop_readlink_cbk_t readlink_cbk;
 		    fop_mknod_cbk_t mknod_cbk;
 		    fop_mkdir_cbk_t mkdir_cbk;
 		    fop_unlink_cbk_t unlink_cbk;
 		    fop_rmdir_cbk_t rmdir_cbk;
 		    fop_symlink_cbk_t symlink_cbk;
 		    fop_rename_cbk_t rename_cbk;
 		    fop_link_cbk_t link_cbk;
 		    fop_truncate_cbk_t truncate_cbk;
 		    fop_open_cbk_t open_cbk;
 		    fop_readv_cbk_t readv_cbk;
 		    fop_writev_cbk_t writev_cbk;
 		    fop_statfs_cbk_t statfs_cbk;
 		    fop_flush_cbk_t flush_cbk;
 		    fop_fsync_cbk_t fsync_cbk;
 		    fop_setxattr_cbk_t setxattr_cbk;
 		    fop_getxattr_cbk_t getxattr_cbk;
 		    fop_removexattr_cbk_t removexattr_cbk;
 		    fop_opendir_cbk_t opendir_cbk;
 		    fop_fsyncdir_cbk_t fsyncdir_cbk;
 		    fop_access_cbk_t access_cbk;
 		    fop_create_cbk_t create_cbk;
 		    fop_ftruncate_cbk_t ftruncate_cbk;
 		    fop_fstat_cbk_t fstat_cbk;
 		    fop_lk_cbk_t lk_cbk;
 		    fop_lookup_cbk_t lookup_cbk;
 		    fop_readdir_cbk_t readdir_cbk;
 		    fop_inodelk_cbk_t inodelk_cbk;
 		    fop_finodelk_cbk_t finodelk_cbk;
 		    fop_entrylk_cbk_t entrylk_cbk;
 		    fop_fentrylk_cbk_t fentrylk_cbk;
 		    fop_xattrop_cbk_t xattrop_cbk;
 		    fop_fxattrop_cbk_t fxattrop_cbk;
 		    fop_fgetxattr_cbk_t fgetxattr_cbk;
 		    fop_fsetxattr_cbk_t fsetxattr_cbk;
 		    fop_rchecksum_cbk_t rchecksum_cbk;
 		    fop_setattr_cbk_t setattr_cbk;
 		    fop_fsetattr_cbk_t fsetattr_cbk;
 		    fop_readdirp_cbk_t readdirp_cbk;
 
 		    /* These 3 are required to keep the index same as GF_FOP_##FOP */
 		    void *forget_placeholder_cbk;
 		    void *release_placeholder_cbk;
 		    void *releasedir_placeholder_cbk;
 
 		    fop_getspec_cbk_t getspec_cbk;
 		    fop_fremovexattr_cbk_t fremovexattr_cbk;
 		    fop_fallocate_cbk_t fallocate_cbk;
 		    fop_discard_cbk_t discard_cbk;
 		    fop_zerofill_cbk_t zerofill_cbk;
 		    fop_ipc_cbk_t ipc_cbk;
 		    fop_seek_cbk_t seek_cbk;
 		    fop_lease_cbk_t lease_cbk;
 		    fop_compound_cbk_t compound_cbk;
 		    fop_getactivelk_cbk_t getactivelk_cbk;
 		    fop_setactivelk_cbk_t setactivelk_cbk;
 		    fop_put_cbk_t put_cbk;
 		    fop_icreate_cbk_t icreate_cbk;
 		    fop_namelink_cbk_t namelink_cbk;
 		    fop_copy_file_range_cbk_t copy_file_range_cbk;
 		};