California Code, Penal Code - PEN § 29130

(a) A licensee shall record the type, model, caliber, or gauge, and serial number of each firearm manufactured or acquired, and the date of the manufacture or acquisition, within one business day of the manufacture or acquisition.

(b) The licensee shall maintain permanently within the building designated in the license the records required pursuant to subdivision (a).

(c) Backup copies of the records described in subdivision (a), whether electronic or hard copy, shall be made at least once a month. These backup records shall be maintained in a facility separate from the one in which the primary records are stored.