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diff --git a/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md b/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md deleted file mode 100644 index 672a8ceb4c6..00000000000 --- a/doc/admin-guide/en-US/markdown/admin_managing_snapshots.md +++ /dev/null @@ -1,316 +0,0 @@ -Managing GlusterFS Volume Snapshots -========================== - -This section describes how to perform common GlusterFS volume snapshot -management operations - -Pre-requisites -===================== - -GlusterFS volume snapshot feature is based on thinly provisioned LVM snapshot. -To make use of snapshot feature GlusterFS volume should fulfill following -pre-requisites: - -* Each brick should be on an independent thinly provisioned LVM. -* Brick LVM should not contain any other data other than brick. -* None of the brick should be on a thick LVM. -* gluster version should be 3.6 and above. - -Details of how to create thin volume can be found at the following link. -https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Logical_Volume_Manager_Administration/thinly_provisioned_volume_creation.html - - -Few features of snapshot are: -============================= - -**Crash Consistency** - -when a snapshot is taken at a particular point-in-time, it is made sure that -the taken snapshot is crash consistent. when the taken snapshot is restored, -then the data is identical as it was at the time of taking a snapshot. - - -**Online Snapshot** - -When the snapshot is being taken the file system and its associated data -continue to be available for the clients. - - -**Quorum Based** - -The quorum feature ensures that the volume is in good condition while the bricks -are down. Quorum is not met if any bricks are down in a n-way replication where -n <= 2. Quorum is met when m bricks are up, where m >= (n/2 + 1) where n is odd, -and m >= n/2 and first brick is up where n is even. snapshot creation fails -if quorum is not met. - - -**Barrier** - -During snapshot creation some of the fops are blocked to guarantee crash -consistency. There is a default time-out of 2 minutes, if snapshot creation -is not complete within that span then fops are unbarried. If unbarrier happens -before the snapshot creation is complete then the snapshot creation operation -fails. This to ensure that the snapshot is in a consistent state. - - - -Snapshot Management -===================== - - -**Snapshot creation** - -Syntax : -*gluster snapshot create <snapname\> <volname\> \[no-timestamp] \[description <description\>\] \[force\]* - -Details : -Creates a snapshot of a GlusterFS volume. User can provide a snap-name and a -description to identify the snap. The description cannot be more than 1024 -characters. -Snapshot will be created by appending timestamp with user provided snap name. -User can override this behaviour by giving no-timestamp flag. - -NOTE : To be able to take a snapshot, volume should be present and it -should be in started state. - ------------------------------------------------------------------------------ - -**Snapshot clone** - -Syntax : -*gluster snapshot clone <clonename\> <snapname\>* - -Details : -Creates a clone of a snapshot. Upon successful completion, a new GlusterFS -volume will be created from snapshot. The clone will be a space efficient clone, -i.e, the snapshot and the clone will share the backend disk. - -NOTE : To be able to take a clone from snapshot, snapshot should be present -and it should be in activated state. - ------------------------------------------------------------------------------ - -**Restoring snaps** - -Syntax : -*gluster snapshot restore <snapname\>* - -Details : -Restores an already taken snapshot of a GlusterFS volume. -Snapshot restore is an offline activity therefore if the volume is -online (in started state) then the restore operation will fail. - -Once the snapshot is restored it will not be available in the -list of snapshots. - ---------------------------------------------------------------------------- - -**Deleting snaps** - -Syntax : -*gluster snapshot delete \(all | <snapname\> | volume <volname\>\)* - -Details : -If snapname is specified then mentioned snapshot is deleted. -If volname is specified then all snapshots belonging to that particular -volume is deleted. If keyword *all* is used then all snapshots belonging -to the system is deleted. - --------------------------------------------------------------------------- - -**Listing of available snaps** - -Syntax: -*gluster snapshot list \[volname\]* - -Details: -Lists all snapshots taken. -If volname is provided, then only the snapshots belonging to -that particular volume is listed. - -------------------------------------------------------------------------- - -**Information of available snaps** - -Syntax: -*gluster snapshot info \[\(snapname | volume <volname\>\)\]* - -Details: -This command gives information such as snapshot name, snapshot UUID, -time at which snapshot was created, and it lists down the snap-volume-name, -number of snapshots already taken and number of snapshots still available -for that particular volume, and the state of the snapshot. - ------------------------------------------------------------------------- - -**Status of snapshots** - -Syntax: -*gluster snapshot status \[\(snapname | volume <volname\>\)\]* - -Details: -This command gives status of the snapshot. -The details included are snapshot brick path, volume group(LVM details), -status of the snapshot bricks, PID of the bricks, data percentage filled for -that particular volume group to which the snapshots belong to, and total size -of the logical volume. - -If snapname is specified then status of the mentioned snapshot is displayed. -If volname is specified then status of all snapshots belonging to that volume -is displayed. If both snapname and volname is not specified then status of all -the snapshots present in the system are displayed. - ------------------------------------------------------------------------- - -**Configuring the snapshot behavior** - -Syntax: -*snapshot config \[volname\] \(\[snap-max-hard-limit <count\>\] \[snap-max-soft-limit <percent>\]\) - | \(\[auto-delete <enable|disable\>\]\) - | \(\[activate-on-create <enable|disable\>\]\)* - -Details: -Displays and sets the snapshot config values. - -snapshot config without any keywords displays the snapshot config values of -all volumes in the system. If volname is provided, then the snapshot config -values of that volume is displayed. - -Snapshot config command along with keywords can be used to change the existing -config values. If volname is provided then config value of that volume is -changed, else it will set/change the system limit. - -snap-max-soft-limit and auto-delete are global options, that will be -inherited by all volumes in the system and cannot be set to individual volumes. - -The system limit takes precedence over the volume specific limit. - -When auto-delete feature is enabled, then upon reaching the soft-limit, -with every successful snapshot creation, the oldest snapshot will be deleted. - -When auto-delete feature is disabled, then upon reaching the soft-limit, -the user gets a warning with every successful snapshot creation. - -Upon reaching the hard-limit, further snapshot creations will not be allowed. - -activate-on-create is disabled by default. If you enable activate-on-create, -then further snapshot will be activated during the time of snapshot creation. -------------------------------------------------------------------------- - -**Activating a snapshot** - -Syntax: -*gluster snapshot activate <snapname\>* - -Details: -Activates the mentioned snapshot. - -Note : By default the snapshot is activated during snapshot creation. - -------------------------------------------------------------------------- - -**Deactivate a snapshot** - -Syntax: -*gluster snapshot deactivate <snapname\>* - -Details: -Deactivates the mentioned snapshot. - -------------------------------------------------------------------------- - -**Accessing the snapshot** - -Snapshots can be activated in 2 ways. - -1) Mounting the snapshot: - -The snapshot can be accessed via FUSE mount (only fuse). To do that it has to be -mounted first. A snapshot can be mounted via fuse by below command - -*mount -t glusterfs <hostname>:/snaps/<snap-name>/<volume-name> <mount-path>* - -i.e. say "host1" is one of the peers. Let "vol" be the volume name and "my-snap" -be the snapshot name. In this case a snapshot can be mounted via this command - -*mount -t glusterfs host1:/snaps/my-snap/vol /mnt/snapshot* - - -2) User serviceability: - -Apart from the above method of mounting the snapshot, a list of available -snapshots and the contents of each snapshot can be viewed from any of the mount -points accessing the glusterfs volume (either FUSE or NFS or SMB). For having -user serviceable snapshots, it has to be enabled for a volume first. User -serviceability can be enabled for a volume using the below command. - -*gluster volume set <volname> features.uss enable* - -Once enabled, from any of the directory (including root of the filesystem) an -access point will be created to the snapshot world. The access point is a hidden -directory cding into which will make the user enter the snapshot world. By -default the hidden directory is ".snaps". Once user serviceability is enabled, -one will be able to cd into .snaps from any directory. Doing "ls" on that -directory shows a list of directories which are nothing but the snapshots -present for that volume. Say if there are 3 snapshots ("snap1", "snap2", -"snap3"), then doing ls in .snaps directory will show those 3 names as the -directory entries. They represent the state of the directory from which .snaps -was entered, at different points in time. - -NOTE: The access to the snapshots are read-only. - -Also, the name of the hidden directory (or the access point to the snapshot -world) can be changed using the below command. - -*gluster volume set <volname> snapshot-directory <new-name>* - -3) Accessing from windows: -The glusterfs volumes can be made accessible by windows via samba. (the -glusterfs plugin for samba helps achieve this, without having to re-export -a fuse mounted glusterfs volume). The snapshots of a glusterfs volume can -also be viewed in the windows explorer. - -There are 2 ways: -* Give the path of the entry point directory -(\\<hostname>\<samba-share>\<directory>\<entry-point path>) in the run command -window -* Go to the samba share via windows explorer. Make hidden files and folders -visible so that in the root of the samba share a folder icon for the entry point -can be seen. - -NOTE: From the explorer, snapshot world can be entered via entry point only from -the root of the samba share. If snapshots have to be seen from subfolders, then -the path should be provided in the run command window. - -For snapshots to be accessible from windows, below 2 options can be used. -A) The glusterfs plugin for samba should give the option "snapdir-entry-path" -while starting. The option is an indication to glusterfs, that samba is loading -it and the value of the option should be the path that is being used as the -share for windows. -Ex: Say, there is a glusterfs volume and a directory called "export" from the -root of the volume is being used as the samba share, then samba has to load -glusterfs with this option as well. - - ret = glfs_set_xlator_option(fs, "*-snapview-client", - "snapdir-entry-path", "/export"); -The xlator option "snapdir-entry-path" is not exposed via volume set options, -cannot be changed from CLI. Its an option that has to be provded at the time of -mounting glusterfs or when samba loads glusterfs. -B) The accessibility of snapshots via root of the samba share from windows -is configurable. By default it is turned off. It is a volume set option which can -be changed via CLI. - -gluster volume set <volname> features.show-snapshot-directory "on/off". By -default it is off. - -Only when both the above options have been provided (i.e snapdir-entry-path -contains a valid unix path that is exported and show-snapshot-directory option -is set to true), snapshots can accessed via windows explorer. - -If only 1st option (i.e. snapdir-entry-path) is set via samba and 2nd option -(i.e. show-snapshot-directory) is off, then snapshots can be accessed from -windows via the run command window, but not via the explorer. - - --------------------------------------------------------------------------------------- |