Start with endurance, then capacity.
A dashcam repeatedly writes video. The project recommends a high-endurance microSD card of at least 64 GB, and suggests 128–256 GB for more HW4 history. SanDisk High Endurance and Samsung PRO Endurance are examples named by the project; this is not a comparative benchmark or a paid placement.
The card also holds the OS and snapshots. The project reports a dashcam drive of about 52 GB on a 64 GB card, plus a few GB of snapshot space. The card’s label is not the same as the space available to the car.
Sentry events or every drive?
Glovebox prioritizes Sentry and saved events. Backing up all driving footage is optional. The README estimates 15–20 GB per hour of HW4 footage and 2.5–3.5 MB/s for Pi Zero 2 W Wi-Fi transfers. Actual footage and speed vary.
How long will the backup take?
Decimal GB and MB. Transfer time only.
Example assumptions, not a guarantee. File overhead, verification, Wi-Fi, interruptions, and the car sleeping can extend the total. Optional keep-awake lasts at most an hour for the first backup.
A bigger card is not faster Wi-Fi.
More capacity gives the car space, but does not remove the wireless bottleneck. At 18 GB and 3 MB/s, transfer alone takes about 100 minutes, longer than the first backup’s maximum keep-awake window. Glovebox resumes interrupted copies when it next reaches your destination.
What happens when storage fills?
The car manages the dashcam drive like a normal USB drive. Glovebox clears events only after they are safely backed up, and drops its oldest snapshots when needed. NAS retention is your responsibility: monitor free space and choose a policy for your storage.
If recordings matter to you, include that folder in your NAS’s own backup plan.
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