On the X32 itself (no iPad, PC, or app required... it's a beautiful thing!). You do however have to purchase this Behringer accessory to provide the SD card slots, which replaces the default plugin card in the back of the X32 unit:
https://www.sweetwater.com/store/de...for-32-channel-sd-sdhc-card-and-usb-recording
It provides for 2 SD slots, so we use it this way:
Slot 1 SD card: Target for all recordings while playing a gig. Thus the card in this slot gets rotated each gig and archived.
Slot 2 SD card: A group of about a dozen songs from previous live gig recordings we use as reference songs during virtual sound checks. Generally these are songs that work well to quickly sound out instrument tones, kick & bass, vocals, etc., mostly to identify any venue-specific EQ needed and to set volume ranges. There's a variety to avoid using a song in the night's setlist as a sound check song if possible.
We're fully automated (and playing against backing tracks from an iPad), so we've also got the iPad (BandHelper) configured to send MIDI to the X32 to start and stop recording to the SD card at the start and end of each song, respectively.
Just to emphasize a point about the brilliance of this feature: the multitrack recordings are the digitized incoming streams from each input to the board, before they hit any channel, effect, or mix processing (uber-pre-fader, and I think pre-trim as well). So once you've got such a recording you can easily experiment with all sorts of mix and processing ideas, whether channel, FX, or overall mix.