parted - gpt
Howto prepare your partitioning in order to create a software raid on top of gpt partitions.
parted /dev/sdb GNU Parted 2.4 Using /dev/sdb Welcome to GNU Parted! Type 'help' to view a list of commands. (parted)
Create a fresh gpt label, erase any preexisting partitions:
mklabel gpt Warning: The existing disk label on /dev/sdb will be destroyed and all data on this disk will be lost. Do you want to continue? Yes/No? yes
Use the hole disk to create one software raid partition:
mkpart raid 1MB -1
Check the layout:
print Model: ATA WDC WD2003FYYS-0 (scsi) Disk /dev/sdb: 2000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 2000GB 2000GB raid
It seem to be necessary to start with 1MB to avoid these annoying messages “Warning: The resulting partition is not properly aligned for best performance.”
All disks in the arry should have the same layout. We could redo the steps above or copy the layout from drive to drive.
Change the drive to work on:
select /dev/sdc ...
Copy the layout with sgdisk:
# Replicate the main device's partition table (here: sdb) on the specified second device (here:sdc). # Note that the replicated partition table is an exact copy, including all GUIDs; if the # device should have its own unique GUIDs, you should use the -G option on the new disk. sgdisk --replicate=/dev/sdc /dev/sdb # Randomize the disk's GUID and all partitions' unique GUIDs (but not their partition type code # GUIDs). This function may be used after cloning a disk in order to render all GUIDs once again # unique. sgdisk --randomize-guids /dev/sdc
alignment (4k sectors)
Howto partition a drive greater than 2TB. I'm going to create a single partition covering the whole available space.
parted --align optimal /dev/sdf Using /dev/sdf Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) mklabel gpt (parted) print Model: ATA WDC WD30EZRX-00M (scsi) Disk /dev/sdf: 3001GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Number Start End Size File system Name Flags (parted) mkpart xfs 0% 100% (parted) print Model: ATA WDC WD30EZRX-00M (scsi) Disk /dev/sdf: 3001GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 3001GB 3001GB xfs (parted) align-check opt Partition number? 1 1 aligned (parted)
The last command
align-check opt checks whether the alignment of the partition is optimal for the 4k block-size of this drive.