Table of contents
- Backup "data" exists in the form of "backup images" created by Amanda.
- "Backup volume images" are created by Amanda client programs and are stored in one or more recording "medium" (whether logical or physical "medium").
- Backup volume images are composed of a sequence of one or more "DLE images" created by Amanda applications.
- Amanda stores the DLE images in a "staging area", and then moves the images to backup media, subject to a "media used per backup run" limit.
- If a DLE image does not completely fit on the media allocated to the backup run, the DLE image remains in the staging area.
- DLE images may be "split" into "chunks" (need to fix this term), so that individual DLE images may span multiple media ("media spanning").
- Physical tapes, DVDs, etc. are examples of Amanda recording "media". For disk-based and S3 backup devices, "vtape" mediums are used.
- The "backup volume images" created during a single Amanda "backup run" contain all of the backup data collected by Amanda from backup clients for each "DLE" in the "backup set".
- "Backup volume images" may span multiple "backup volume mediums", if "spanning" has been enabled by setting "backup media per run" to a value greater than "1 medium" on the "Backup When" page.
- "Backup volume" refers to the logical collection of "backup volume images" and "backup volume media" used for a single Amanda "backup run".
- A "medium" occupies a "slot" in a "device binding".
- A "device binding" defines a device and device properties for use by a specific "backup set".
- A "device binding" is defined on the new ZMC "Backup Where" page by identifying a "device profile" and defining the properties and characteristics unique to the "backup set".
Without the concept of "medium"/"vtape" some media management and backup configuration features in ZMC become nearly impossible to understand and explain in the GUI. Merging the distinctly different concepts of "vtape", "slot", "volume", and/or "data" leads to ambiguities and confusion. Thus, I propose maintaining these distinctions in the ZMC, as long as the ZMC GUI exposes form fields and emits output requiring such distinctions.
ZMC Devices
Storage devices are first created in ZMC as device profiles. These profiles are then connected to a ZMC backup set to create a "device binding". A device profile specifies general, immutable, characteristics of a storage device, while a device bindings provide backup-set specific values for the device (e.g. which slots to use).
ZMC=>Amanda Terminology Translation
- archive (applied to media) = setting "no-reuse" column in tapelist (see medium status)
- backup cycle = Amanda's "dumpcycle" parameter.
- backup set: A fully configured ZMC backup set includes:
- backup volumes per run = "runtapes" parameter.
- Amanda configuration
- device binding named /etc/amanda/<Amanda configuration>/[disk|changer|tape|s3]-[2|3]-<device profile name>.yml
- device binding configuration file created by Yasumi from the YAML file above, have the same file name, but a ".conf" suffix.
- Amanda <device-profile-name>-changer.conf containing the usual things found in Amanda changer.conf files.
- amanda.conf file with: includefile <binding.conf file from above>
- backup volume = all rows in the Amanda configuration's "tapelist" file having the same timestamp
- chunk = split
- device binding = sum of a per-device "changer.conf" file, and all the Amanda ".conf" parameters for a particular physical (e.g. tape changer) or virtual device (e.g. S3, Amand vtape changer).
- media = one or more vtapes/tapes/etc.
- medium status = a row in Amanda configuration's "tapelist" file
- volumes in rotation = Amanda's "tapecycle" parameter.