Dahua DH-XVR54 L-I2 Series User Manual page 318

For devices that support 2 or more HDDs, you can switch the quota mode between

version 1 and version 2.
 V1: Select a channel and then configure the disk quota for each disk.
 V2: Select a channel and then configure the parameters including recording
duration, bit rate, storage capacity of pictures.
Disk quota (one-HDD device)
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User's Manual