FAT32 or exFAT for your Rivian’s USB drive
Updated · by the Overlook team at CTT Apps (about us)
Forum threads go back and forth on whether a Rivian wants FAT32 or exFAT. The short answer: the car records to drives in either format. Drives the car formats itself come out as exFAT, named android. The Overlook Cache makes its drive as FAT32 by default, and the car records to that just as happily. What matters more is the drive’s size and its speed.
What Rivian asks of a drive
| Requirement | Why it matters | |
|---|---|---|
| Size | 128 GB to 2 TB | Below 128 GB the car may refuse it; beyond 2 TB is outside what it supports (and FAT32’s own limit with ordinary 512-byte sectors). |
| Speed | At least 20 MB/s of writes, including random writes | The car tests the drive when it sets it up and records several cameras at once. A slow drive fails the test (“Speed testing could not be completed”) or drops footage. |
| Format | FAT32 or exFAT | The car offers to format a drive it can’t use. Let it, if there’s nothing on the drive you need. |
Speed is the requirement people trip over, not format. See choosing an SD card or SSD for what the labels mean.
What actually differs between the two
| FAT32 | exFAT | |
|---|---|---|
| Largest file | 4 GiB minus one byte | No practical limit |
| Largest drive | 2 TiB with 512-byte sectors | No practical limit |
| File times | Local time, 2-second steps, no time zone | 10 ms steps, with the UTC offset |
| Typical cluster size at 128 GB–2 TB | 32 KiB | 128 KiB |
| Journal (power-cut protection) | None | None |
| Windows can create it at this size | Not with its built-in Format dialog | Yes |
| macOS can create it | Yes (“MS-DOS (FAT)”) | Yes (“ExFAT”) |
| Reads on Mac, Windows, Linux | Yes | Yes |
The 4 GB file limit doesn’t bite
FAT32’s best-known limit is that no single file can reach 4 GiB. A Rivian splits continuous drive recording into 15-minute parts, one file per camera, and at the rates we see each part is around a gigabyte. Gear Guard events, incidents and saved clips are shorter still. Nothing the car writes comes close to the limit.
Timestamps are a wash
exFAT records file times more precisely and with a time zone, which sounds useful. In practice neither matters for Rivian footage: the recording’s time is in its file name and inside the MP4 itself, and those are what Overlook uses. (One quirk worth knowing: Gear Guard file names are in UTC while drives are named in local time. The folders guide explains.)
Cluster size barely matters here
A filesystem hands out space in clusters. Big clusters waste space on small files, but a drive full of gigabyte-sized videos wastes almost nothing either way. With 32 KiB clusters a 128 GB FAT32 drive has about 4 million of them and a 2 TB drive about 61 million, well within what FAT32 can track.
Neither survives a power cut gracefully
Both formats update their tables in place without a journal, so a file being written when power goes can be left cut short or marked as using space it doesn’t. That’s why it pays to wait for the car to finish recording before unplugging, and why a computer may offer to “repair” a drive after a bad unplug. Let the car keep using it; don’t let the computer format it.
Which to choose
| Your situation | Pick |
|---|---|
| A new, ordinary USB drive or SSD | Let the car format it (exFAT). Nothing to install, nothing to get wrong. |
| You format drives on Windows | exFAT, from File Explorer’s Format option. |
| Something else needs to read the drive and only understands FAT32 | FAT32 (format on a Mac or Linux). |
| An Overlook Cache | Leave it on FAT32, its default. exFAT is a setting if you prefer it. |
How to format a drive
Formatting erases everything on the drive and gives it a new volume serial, so the car will list it as a new drive. Copy off anything you need first.
Mac
- Open Disk Utility and choose View → Show All Devices.
- Select the drive itself (the top line, not the volume under it) and click Erase.
- Format: ExFAT or MS-DOS (FAT). Scheme: Master Boot Record.
Or in Terminal, after finding the disk with diskutil list external:
diskutil eraseDisk ExFAT android MBR disk4
diskutil eraseDisk FAT32 RIVIAN MBR disk4Windows
In File Explorer, right-click the drive, choose Format, pick exFAT and start. Windows’ built-in tools have long refused to make FAT32 on drives over 32 GB; if you need FAT32 on Windows, format it in the car or on a Mac instead.
Linux
sudo mkfs.exfat -L android /dev/sdX1
sudo mkfs.fat -F 32 -s 64 -n RIVIAN /dev/sdX1Replace sdX1 with the drive’s partition from lsblk, and double-check it: these commands don’t ask. -s 64 gives 32 KiB clusters, the size Windows and Android use for FAT32 drives this big.
Partitions: keep it to one
A drive holds a partition table and, inside it, one or more partitions, each with its own filesystem. For the car, keep to the classic layout for removable drives: a Master Boot Record partition table with one partition filling the drive. That’s what the Mac commands above make, what Windows makes for a USB stick, and what the Overlook Cache uses. A drive with several partitions may appear in the car as several drives, each with its own serial (see two USB drives), and a GUID (GPT) layout is something we’d avoid for no benefit.
When the car formats a drive
If you plug in a drive the car can’t use (the wrong format, or a fresh one), it offers to format it. Say yes only if there’s nothing on it you need. The car then makes it exFAT, names it android, and runs its write-speed test; a drive that’s too slow gets “Speed testing could not be completed”. Folders such as GearGuardVideo appear inside a vehicle folder as the car starts recording. Formatting writes a new volume serial, so the drive is listed in the car under a new code afterwards.
How the Overlook Cache does it
An Overlook Cache makes the car’s drive as a disk image laid out the way Windows and Android lay out a large FAT32 drive: a Master Boot Record with one partition of type 0x0C (FAT32 with LBA) starting at 1 MiB, 32 KiB clusters, named OVERLOOK. With drive_format=exfat it makes an exFAT drive named android instead, like the car would. Prepare the drive for the car on its status page or in the app remakes the drive in either format, empty, at the same size; it asks first, warns if any recordings aren’t backed up, and waits until the car has stopped writing.
The Cache, Overlook in the browser and the iPhone and iPad app all read both formats.
Troubleshooting and questions
How do I check what format my drive is?
Mac: diskutil info /Volumes/android and look for “File System Personality”. Windows: right-click the drive, Properties, “File system”. Linux: lsblk -f.
Can I use NTFS, APFS or Mac OS Extended?
Don’t rely on them. Stick to FAT32 or exFAT; expect the car to offer to format anything else.
Will converting from one to the other keep my recordings?
No. Changing the format means formatting, which erases the drive. Copy recordings off first.
The car keeps asking to format my drive
It may not recognise the format, or the drive may be smaller than 128 GB or failing its speed test. Try a different, faster drive before blaming the format.
Is a 4 TB drive OK if I format it exFAT?
exFAT can handle it, but Rivian supports drives up to 2 TB. Stay within that.
Related guides
- Why your Rivian shows two USB drives, and how to tell them apartWhat “USB Drive (EBD1-BD08)” means, where that code comes from, and how to read it on any computer.
- Choosing an SD card or SSD for Rivian Gear GuardWhat A2, V30, U3 and “high endurance” promise, why random writes matter, and how to test what you bought.
- What’s on your Rivian’s USB drive: folders and files explainedGearGuardVideo, RoadCam, IncidentCam, file names, cameras and 15-minute segments.