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96 lines
4.4 KiB
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96 lines
4.4 KiB
Text
[[snapshots-filesystem-repository]]
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=== Shared file system repository
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include::{es-ref-dir}/snapshot-restore/on-prem-repo-type.asciidoc[]
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Use a shared file system repository to store snapshots on a shared file system.
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To register a shared file system repository, first mount the file system to the
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same location on all master and data nodes. Then add the file system's path or
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parent directory to the `path.repo` setting in `elasticsearch.yml` for each
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master and data node. For running clusters, this requires a
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<<restart-cluster-rolling,rolling restart>> of each node.
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Supported `path.repo` values vary by platform:
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include::{es-ref-dir}/tab-widgets/register-fs-repo-widget.asciidoc[]
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[[filesystem-repository-settings]]
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==== Repository settings
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`chunk_size`::
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(Optional, <<byte-units,byte value>>)
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Maximum size of files in snapshots. In snapshots, files larger than this are
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broken down into chunks of this size or smaller. Defaults to `null` (unlimited
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file size).
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`compress`::
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(Optional, Boolean)
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If `true`, metadata files, such as index mappings and settings, are compressed
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in snapshots. Data files are not compressed. Defaults to `true`.
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`location`::
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(Required, string)
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Location of the shared filesystem used to store and retrieve snapshots. This
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location must be registered in the `path.repo` setting on all master and data
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nodes in the cluster.
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Unlike `path.repo`, this setting supports only a single file path.
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`max_number_of_snapshots`::
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(Optional, integer)
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Maximum number of snapshots the repository can contain.
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Defaults to `Integer.MAX_VALUE`, which is `2^31-1` or `2147483647`.
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include::repository-shared-settings.asciidoc[]
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==== Troubleshooting a shared file system repository
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{es} interacts with a shared file system repository using the file system
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abstraction in your operating system. This means that every {es} node must be
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able to perform operations within the repository path such as creating,
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opening, and renaming files, and creating and listing directories, and
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operations performed by one node must be visible to other nodes as soon as they
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complete.
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Check for common misconfigurations using the <<verify-snapshot-repo-api>> API
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and the <<repo-analysis-api>> API. When the repository is properly configured,
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these APIs will complete successfully. If the verify repository or repository
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analysis APIs report a problem then you will be able to reproduce this problem
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outside {es} by performing similar operations on the file system directly.
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If the verify repository or repository analysis APIs fail with an error
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indicating insufficient permissions then adjust the configuration of the
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repository within your operating system to give {es} an appropriate level of
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access. To reproduce such problems directly, perform the same operations as
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{es} in the same security context as the one in which {es} is running. For
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example, on Linux, use a command such as `su` to switch to the user as which
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{es} runs.
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If the verify repository or repository analysis APIs fail with an error
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indicating that operations on one node are not immediately visible on another
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node then adjust the configuration of the repository within your operating
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system to address this problem. If your repository cannot be configured with
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strong enough visibility guarantees then it is not suitable for use as an {es}
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snapshot repository.
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The verify repository and repository analysis APIs will also fail if the
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operating system returns any other kind of I/O error when accessing the
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repository. If this happens, address the cause of the I/O error reported by the
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operating system.
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TIP: Many NFS implementations match accounts across nodes using their _numeric_
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user IDs (UIDs) and group IDs (GIDs) rather than their names. It is possible
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for {es} to run under an account with the same name (often `elasticsearch`) on
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each node, but for these accounts to have different numeric user or group IDs.
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If your shared file system uses NFS then ensure that every node is running with
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the same numeric UID and GID, or else update your NFS configuration to account
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for the variance in numeric IDs across nodes.
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[[repository-fs-linearizable-registers]]
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==== Linearizable register implementation
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The linearizable register implementation for shared filesystem repositories is
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based around file locking. To perform a compare-and-exchange operation on a
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register, {es} first locks he underlying file and then writes the updated
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contents under the same lock. This ensures that the file has not changed in the
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meantime.
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