Reformatting open system drives for migration

The 524-byte sector format is required for the migration of data from open system drives to the DS8000 storage system. You must back up data in temporary storage before you start the drive reformatting process.

The 524-byte sector replaces the traditional 512-byte sector of fixed-block architecture drives. The 524-byte sector format requires that you reformat all drives that you are migrating to the storage system. Because reformatting erases any data that is already contained on the drives, you must back up the data to some type of temporary storage.

You can use the drives for either direct migration of data or as temporary storage while the existing drives are moved. If not possible, use a removable media device such as a tape drive to temporarily store the data while you reformat the drives.

The AIX LVM uses a fixed-byte sector of 512 bytes. When used in a storage system, the format is a fixed-byte sector of 524 bytes. The data portion of the sector remains at 512 bytes. IBM® i headers use 8 more bytes. A 2-byte sequence number and a 2-byte longitudinal redundancy check (LRC) complete the extra bytes. The storage system LIC uses the sequence number and LRC. The storage system does not transfer them to the host system.

Most fixed-block architectures use a fixed-byte sector of 512 bytes. Such is the case for most UNIX systems, including AIX. When used in a storage system, the format of a drive has a fixed-byte sector of 524 bytes. The 524-byte sector format enables the storage system to connect to a wide range of host systems and share data between them.

The 524-byte sector on the drive is independent of the sector size that is shown to the host for a device type emulation. Most LUNs for open-systems hosts display a 512-byte sector.

IBM i host systems use 8 bytes at the start of the sector. UNIX host systems do not use the 8 bytes when attached to the storage system. The data portion of the sector remains at 512 bytes for all host systems. A 2-byte sequence number and a 2-byte LRC increase the size of the sector to 524 bytes.