![]() Some boot loaders for BIOS-based systems make use of a BIOS Boot Partition ( gdisk internal code 0圎F02), in which the secondary boot loader is stored, possibly without the benefit of a filesystem.(Note that GNU Parted identifies such partitions as having the "boot flag" set.) (Smaller ESPs are common, but some EFIs have flaky FAT drivers that necessitate a larger partition for reliable operation.) Boot-related files are stored here. I recommended making this partition 550 MiB. Boot disks for EFI-based systems require an EFI System Partition ( gdisk internal code 0圎F00) formatted as FAT-32.For data (non-boot) disks, and for boot disks used on BIOS-based computers with GRUB as the boot loader, partitions may be created in whatever order and in whatever sizes are desired. ![]() When creating a fresh partition table, certain considerations may be in order: (Doing this may require you to update your /etc/fstab file.) These gaps are harmless, but you can eliminate them by using the -s ( -sort) option, if you like. The MBR-to-GPT conversion will leave at least one gap in the partition numbering if the original MBR used logical partitions. Boot problems are particularly likely if you're multi-booting with any GPT-unaware OS. This action is potentially dangerous! Your system may become unbootable, and partition type codes may become corrupted if the disk uses unrecognized type codes. If you use the -g option, sgdisk replaces the MBR or disklabel with a GPT. If you specify any option that results in changes to an MBR or BSD disklabel, sgdisk ignores those changes unless the -g ( -mbrtogpt), -z ( -zap), or -Z ( -zap-all) option is used. (BSD disklabels are likely to have unusable first and/or final partitions because they overlap with the GPT data structures, though.) GPT fdisk can identify, but not use data in, Apple Partition Map (APM) disks, which are used on 680x0- and PowerPC-based Macintoshes. If sgdisk finds a valid MBR or BSD disklabel but no GPT data, it will attempt to convert the MBR or disklabel into GPT form. If it finds valid GPT data, sgdisk will use it. Upon start, sgdisk attempts to identify the partition type in use on the disk. For example, you should make Mac OS X partitions with the Mac OS X Disk Utility program and Linux partitions with the Linux gdisk, sgdisk, or GNU Parted programs. Thus, GPT data structures, and therefore sgdisk, do not need to deal with CHS geometries and all the problems they create.įor best results, you should use an OS-specific partition table program whenever possible. GPT drops CHS addressing and uses 64-bit LBA mode exclusively. The MBR partitioning system uses a combination of cylinder/head/sector (CHS) addressing and logical block addressing (LBA). Note that only raw disk images are supported sgdisk cannot work on compressed or other advanced disk image formats. The program can also operate on disk image files, which can be either copies of whole disks (made with dd, for instance) or raw disk images used by emulators such as QEMU or VMWare. Ordinarily, sgdisk operates on disk device files, such as /dev/sda or /dev/hda under Linux, /dev/disk0 under Mac OS X, or /dev/ad0 or /dev/da0 under FreeBSD. (The program may query the user when certain errors are encountered, though.) The program's name is based on sfdisk, but the user options of the two programs are entirely different from one another. The sgdisk program employs a user interface that's based entirely on the command line, making it suitable for use in scripts or by experts who want to make one or two quick changes to a disk. GPT, as well as GPT terminology and structure, see the extended gdisk documentation at or consult Wikipedia. Some advanced data manipulation and recovery options require you to understand the distinctions between the main and backup data, as well as between the GPT headers and the partition tables. ![]() This man page documents the command-line sgdisk program. Either program will automatically convert an old-style Master Boot Record (MBR) partition table or BSD disklabel stored without an MBR carrier partition to the newer Globally Unique Identifier (GUID) Partition Table (GPT) format, or will load a GUID partition table. It consists of two programs: the text-mode interactive gdisk and the command-line sgdisk. GPT fdisk is a text-mode menu-driven package for creation and manipulation of partition tables. Command-line GUID partition table (GPT) manipulator for Linux and Unix Synopsis
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