Disk formats

The disk format determines how much of the disk’s raw capacity can be used for data storage. Also, some disk formats cannot be combined in the same aggregate.

All new storage systems use block checksum disks (BCDs).

The disk formats are as follows:

FC and SAS BCDs use 520 bytes per sector. 512 bytes per sector are available for data. 8 bytes per sector are used for the checksum.
ATA and SATA BCDs use 512 bytes per sector. 1 out of every 8 sectors is used for the checksum.

If you have an older storage system, it might have zoned checksum disks (ZCDs), which have a disk format of 512 bytes per sector, and use one sector for the checksum for every 64 data sectors. There are rules about combining BCDs and ZCDs in the same aggregate.

Parent topic: How Data ONTAP works with disks

Related concepts

Checksum type rules used when you add disks to an aggregate