Upgrading from Arq 6
If you had Arq 6 installed and you install Arq 7, when you first open the Arq 7 app, Arq will load the configuration from Arq 6 into Arq 7.
Arq 7’s backup format differs from Arq 6 in that Arq 7 stores a separate backup record for each selected item (folder, file, volume) in the backup plan, where Arq 6 stored 1 “snapshot” containing all the folders/files/volumes it found at backup time.
During the first backup, Arq 7 will create its own list of backup record files. It will read the list of Arq 6 “snapshots” created by Arq 6 and will create a small JSON file (usually about 2 KB) for each item in each volume found in existing Arq 6 “snapshot”, containing metadata (UUID, creation date, etc) and a “pointer” to the directory metadata and file data referenced by the Arq 6 snapshot. It will match up the selected items across “snapshots” by volume identifier so that backup records for a given volume are shown together.
Subsequent backup record files created by Arq 7 will reuse the Arq 6 file data where possible as part of its de-duplication logic but will “point” to new, Arq7-style directory metadata.
Browsing backup records created by Arq 7 from a new computer will be instantaneous thanks to Arq 7’s new data structure. Browsing backup records that “point” to directory metadata created by Arq 6 will require caching “pack indexes” before the backup record can be shown.
Modifications to data created by Arq 6
Arq 7 doesn’t “import” the Arq 6 data; it reuses it as described above.
If you don’t specify any retention or budget rules that delete backup records, the Arq 6 “snapshots” won’t be modified.
If you do specify retention or budget rules, or you manually delete backup records, Arq 7 may delete data referenced by the (now unused) Arq 6 data structures.
Adopting a backup set created by Arq 6
If you click on a backup set created by Arq 6 and click Adopt, Arq 7 follows the same process for that backup set that it does when automatically using and Arq 6 backup set, as described above.
Do NOT downgrade
Please do not switch to an older version of Arq. Installing an older version of Arq on top of a new version of Arq is not supported for many reasons, including:
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Arq’s internal data structures are updated by Arq version updates and are not backward-compatible with older versions of Arq.
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If Arq 7 is reusing Arq 6 data, it reads the Arq 6 data and creates its backup record JSON files once; it does not anticipate further changes to the Arq 6 data.
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Switching back and forth between older and newer versions of Arq can cause corruption and data loss.