# HPE Alletra - `alletra` [HPE Alletra](https://www.hpe.com/emea_europe/en/hpe-alletra.html) is a storage solution. It offers the consumption of redundant block storage across the network. LXD supports connecting to HPE Alletra storage through . In addition, HPE Alletra offers copy-on-write snapshots, thin provisioning, and other features. Using HPE Alletra with LXD requires a HPE Alletra WSAPI version `1`. Additionally, ensure that the required kernel modules for the selected protocol are installed on your host system. ## Terminology Each storage pool created in LXD using an HPE Alletra driver represents an HPE Alletra *volume set*, which is an abstraction that groups multiple volumes under a specific name. LXD creates volumes within a volume set that is identified by the storage pool name. When the first volume needs to be mapped to a specific LXD host, a corresponding HPE Alletra host entity is created with the name of the LXD host and a suffix of the used protocol. For example, if the LXD host is `host01` and the mode is `nvme/tcp`, the resulting HPE Alletra host entity would be `host01-nvme-tcp`. The HPE Alletra host is then connected with the required volumes to allow attaching and accessing volumes from the LXD host. The HPE Alletra host is automatically removed once there are no volumes connected to it. ## The `alletra` driver in LXD The `alletra` driver in LXD uses HPE Alletra volumes for custom storage volumes, instances, and snapshots. All created volumes are thin-provisioned block volumes. If required (for example, for containers and custom file system volumes), LXD formats the volume with a desired file system. LXD expects HPE Alletra to be pre-configured with a specific service (such as iSCSI) on the network interfaces whose addresses you provide during storage pool configuration. Furthermore, LXD assumes that it has full control over the HPE Alletra volume sets it manages. Therefore, do not keep any volumes in HPE Alletra volume sets unless they are owned by LXD, because LXD might disconnect or even delete them. This driver provides remote storage. As a result, and depending on the internal network, storage access might be a bit slower compared to local storage. On the other hand, using remote storage has significant advantages in a cluster setup: all cluster members have access to the same storage pools with the exact same contents, without the need to synchronize them. When creating a new storage pool using the `alletra` driver, LXD automatically discovers the array’s qualified name and target address. Upon successful discovery, LXD attaches all volumes that are connected to the HPE Alletra host that is associated with a specific LXD server. HPE Alletra hosts and volume connections () are fully managed by LXD. Volume snapshots are also supported by HPE Alletra. When a volume with at least one snapshot is copied, LXD sequentially creates snapshots on the destination volume from snapshots on the source volume. Finally, once all snapshots are copied, the source volume is copied into the destination volume. ### Volume names As a Pure storage driver, the `alletra` driver uses the volume’s [`volatile.uuid`](#storage-alletra-volume-conf:volatile.uuid) to generate a volume name. For example, a UUID `5a2504b0-6a6c-4849-8ee7-ddb0b674fd14` is first trimmed of any hyphens (`-`), resulting in the string `5a2504b06a6c48498ee7ddb0b674fd14`. To distinguish volume types and snapshots, special identifiers are prepended and appended to the volume names, as depicted in the table below: | Type | Identifier | Example | |-----------------|--------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | Container | `c-` | `c-5a2504b06a6c48498ee7ddb0b674fd14` | | Virtual machine | `v-` | `v-5a2504b06a6c48498ee7ddb0b674fd14-b` (block volume) and `v-5a2504b06a6c48498ee7ddb0b674fd14` (file system volume) | | Image (ISO) | `i-` | `i-5a2504b06a6c48498ee7ddb0b674fd14-i` | | Custom volume | `u-` | `u-5a2504b06a6c48498ee7ddb0b674fd14` (file system volume) and `u-5a2504b06a6c48498ee7ddb0b674fd14-b` (block volume) | | Snapshot | `s` | `sc-5a2504b06a6c48498ee7ddb0b674fd14` (container snapshot), `sv-5a2504b06a6c48498ee7ddb0b674fd14-b` (VM snapshot) and `su-5a2504b06a6c48498ee7ddb0b674fd14` (custom volume snapshot) | ### Limitations The `alletra` driver has the following limitations: Volume size constraints : The minimum volume size (quota) is `256MiB` and must be a multiple of `256MiB`. If the requested size does not meet these conditions, LXD automatically rounds it up to the nearest valid value. Sharing an HPE Alletra storage pool between multiple LXD installations : Sharing an HPE Alletra array among multiple LXD installations is possible, provided that the installations use distinct storage pool names. Storage pools are implemented as volume sets on the array, and volume set names must be unique. Recovering HPE Alletra storage pools : Recovery of HPE Alletra storage pools using `lxd recover` is currently not supported. ## Configuration options The following configuration options are available for storage pools that use the `alletra` driver, as well as storage volumes in these pools. ### Storage pool configuration `alletra.cpg` HPE Alletra Common Provisioning Group (CPG) name [](#storage-alletra-pool-conf:alletra.cpg) | **Key:** | `alletra.cpg` | |-------------|-----------------| | **Type:** | string | `alletra.mode` How volumes are mapped to the local server [](#storage-alletra-pool-conf:alletra.mode) | **Key:** | `alletra.mode` | |--------------|------------------| | **Type:** | string | | **Default:** | `nvme/tcp` | The mode to use to map storage volumes to the local server. Supported values are `iscsi` and `nvme/tcp`. `alletra.target` List of target addresses. [](#storage-alletra-pool-conf:alletra.target) | **Key:** | `alletra.target` | |--------------|-----------------------| | **Type:** | string | | **Default:** | all available targets | A comma-separated list of target addresses. If empty, LXD discovers and connects to all available targets. Otherwise, it only connects to the specified addresses. `alletra.user.name` HPE Alletra storage admin username [](#storage-alletra-pool-conf:alletra.user.name) | **Key:** | `alletra.user.name` | |-------------|-----------------------| | **Type:** | string | `alletra.user.password` HPE Alletra storage admin password [](#storage-alletra-pool-conf:alletra.user.password) | **Key:** | `alletra.user.password` | |-------------|---------------------------| | **Type:** | string | `alletra.wsapi` Address of the HPE Alletra Storage UI/WSAPI [](#storage-alletra-pool-conf:alletra.wsapi) | **Key:** | `alletra.wsapi` | |-------------|-------------------| | **Type:** | string | `alletra.wsapi.verify` Whether to verify the HPE Alletra Storage UI/WSAPI certificate [](#storage-alletra-pool-conf:alletra.wsapi.verify) | **Key:** | `alletra.wsapi.verify` | |--------------|--------------------------| | **Type:** | bool | | **Default:** | `true` | `rsync.bwlimit` Upper limit on the socket I/O for `rsync` [](#storage-alletra-pool-conf:rsync.bwlimit) | **Key:** | `rsync.bwlimit` | |--------------|-------------------| | **Type:** | string | | **Default:** | `0` (no limit) | | **Scope:** | global | When `rsync` must be used to transfer storage entities, this option specifies the upper limit to be placed on the socket I/O. `rsync.compression` Whether to use compression while migrating storage pools [](#storage-alletra-pool-conf:rsync.compression) | **Key:** | `rsync.compression` | |--------------|-----------------------| | **Type:** | bool | | **Default:** | `true` | | **Scope:** | global | `volume.size` Size/quota of the storage volume [](#storage-alletra-pool-conf:volume.size) | **Key:** | `volume.size` | |--------------|-----------------| | **Type:** | string | | **Default:** | `10GiB` | Default storage volume size rounded to 256MiB. The minimum size is 256MiB. #### TIP In addition to these configurations, you can also set default values for the storage volume configurations. See storage-configure-vol-default. ### Storage volume configuration `block.filesystem` File system of the storage volume [](#storage-alletra-volume-conf:block.filesystem) | **Key:** | `block.filesystem` | |----------------|---------------------------------------------------| | **Type:** | string | | **Default:** | same as `volume.block.filesystem` | | **Condition:** | block-based volume with content type `filesystem` | Valid options: `btrfs`, `ext4`, `xfs` If not set, `ext4` is assumed. `block.mount_options` Mount options for block-backed file system volumes [](#storage-alletra-volume-conf:block.mount_options) | **Key:** | `block.mount_options` | |----------------|---------------------------------------------------| | **Type:** | string | | **Default:** | same as `volume.block.mount_options` | | **Condition:** | block-based volume with content type `filesystem` | `security.shared` Enable volume sharing [](#storage-alletra-volume-conf:security.shared) | **Key:** | `security.shared` | |----------------|---------------------------------------------| | **Type:** | bool | | **Default:** | same as `volume.security.shared` or `false` | | **Condition:** | virtual-machine or custom block volume | | **Scope:** | global | Enable this option to allow the volume to be shared across multiple instances despite the possibility of data loss. `security.shifted` Enable ID shifting overlay [](#storage-alletra-volume-conf:security.shifted) | **Key:** | `security.shifted` | |----------------|----------------------------------------------| | **Type:** | bool | | **Default:** | same as `volume.security.shifted` or `false` | | **Condition:** | custom volume | | **Scope:** | global | Enable this option to allow the volume to be attached to multiple isolated instances. `security.unmapped` Disable ID mapping for the volume [](#storage-alletra-volume-conf:security.unmapped) | **Key:** | `security.unmapped` | |----------------|-----------------------------------------------| | **Type:** | bool | | **Default:** | same as `volume.security.unmapped` or `false` | | **Condition:** | custom volume | | **Scope:** | global | `size` Size/quota of the storage volume [](#storage-alletra-volume-conf:size) | **Key:** | `size` | |--------------|----------| | **Type:** | string | | **Default:** | `10GiB` | Default storage volume size rounded to 256MiB. The minimum size is 256MiB. `snapshots.expiry` Time until snapshots are deleted [](#storage-alletra-volume-conf:snapshots.expiry) | **Key:** | `snapshots.expiry` | |----------------|-----------------------------------| | **Type:** | string | | **Default:** | same as `volume.snapshots.expiry` | | **Condition:** | custom volume | | **Scope:** | global | Specify an expression like `1M 2H 3d 4w 5m 6y`. `snapshots.pattern` Template for the snapshot name [](#storage-alletra-volume-conf:snapshots.pattern) | **Key:** | `snapshots.pattern` | |----------------|------------------------------------------------| | **Type:** | string | | **Default:** | same as `volume.snapshots.pattern` or `snap%d` | | **Condition:** | custom volume | | **Scope:** | global | You can specify a naming template for scheduled snapshots and unnamed snapshots. The `snapshots.pattern` option takes a Pongo2 template string to format the snapshot name. To add a time stamp to the snapshot name, use the Pongo2 context variable `creation_date`. Make sure to format the date in your template string to avoid forbidden characters in the snapshot name. For example, set `snapshots.pattern` to `{{ creation_date|date:'2006-01-02_15-04-05' }}` to name the snapshots after their time of creation, down to the precision of a second. Another way to avoid name collisions is to use the placeholder `%d` in the pattern. If no matching snapshots exist, the placeholder is replaced with `0`. Otherwise, it is replaced with the next snapshot index, which is one higher than the highest existing matching snapshot index. `snapshots.schedule` Schedule for automatic volume snapshots [](#storage-alletra-volume-conf:snapshots.schedule) | **Key:** | `snapshots.schedule` | |----------------|------------------------------| | **Type:** | string | | **Default:** | same as `snapshots.schedule` | | **Condition:** | custom volume | | **Scope:** | global | Specify either a cron expression (` `), a comma-separated list of schedule aliases (`@hourly`, `@daily`, `@midnight`, `@weekly`, `@monthly`, `@annually`, `@yearly`), or leave empty to disable automatic snapshots (the default). `volatile.devlxd.owner` ID of the DevLXD identity that owns the volume [](#storage-alletra-volume-conf:volatile.devlxd.owner) | **Key:** | `volatile.devlxd.owner` | |--------------|---------------------------| | **Type:** | string | | **Default:** | DevLXD owner identity ID | | **Scope:** | global | `volatile.idmap.last` JSON-serialized UID/GID map that has been applied to the volume [](#storage-alletra-volume-conf:volatile.idmap.last) | **Key:** | `volatile.idmap.last` | |----------------|-------------------------| | **Type:** | string | | **Condition:** | filesystem | `volatile.idmap.next` JSON-serialized UID/GID map that has been applied to the volume [](#storage-alletra-volume-conf:volatile.idmap.next) | **Key:** | `volatile.idmap.next` | |----------------|-------------------------| | **Type:** | string | | **Condition:** | filesystem | `volatile.uuid` Volume UUID [](#storage-alletra-volume-conf:volatile.uuid) | **Key:** | `volatile.uuid` | |--------------|-------------------| | **Type:** | string | | **Default:** | random UUID | | **Scope:** | global |