Partitioning your disk simply refers to the act of breaking up your disk into sections. Each section is then independent of the others. It's roughly equivalent to putting up walls inside a house; if you add furniture to one room it doesn't affect any other room. Whenever this section talks about disks you should translate this into a DASD or VM minidisk in the &arch-title; world. Also a machine means an LPAR or VM guest in this case. If you already have an operating system on your system (Windows 9x, Windows NT/2000/XP/2003/Vista/7, OS/2, MacOS, Solaris, FreeBSD, …) (VM, z/OS, OS/390, …) which uses the whole disk and you want to stick &debian; on the same disk, you will need to repartition it. &debian; requires its own hard disk partitions. It cannot be installed on Windows or Mac OS X partitions. It may be able to share some partitions with other Unix systems, but that's not covered here. At the very least you will need a dedicated partition for the &debian; root filesystem. You can find information about your current partition setup by using a partitioning tool for your current operating system, such as the integrated Disk Manager in Windows or fdisk in DOS, such as Disk Utility, Drive Setup, HD Toolkit, or MacTools, such as the VM diskmap. Partitioning tools always provide a way to show existing partitions without making changes. In general, changing a partition with a file system already on it will destroy any information there. Thus you should always make backups before doing any repartitioning. Using the analogy of the house, you would probably want to move all the furniture out of the way before moving a wall or you risk destroying it. Several modern operating systems offer the ability to move and resize certain existing partitions without destroying their contents. This allows making space for additional partitions without losing existing data. Even though this works quite well in most cases, making changes to the partitioning of a disk is an inherently dangerous action and should only be done after having made a full backup of all data. For FAT/FAT32 and NTFS partitions as used by DOS and Windows systems, the ability to move and resize them losslessly is provided both by &d-i; as well as by the integrated Disk Manager of Windows 7. To losslessly resize an existing FAT or NTFS partition from within &d-i;, go to the partitioning step, select the option for manual partitioning, select the partition to resize, and simply specify its new size. FIXME: write about HP-UX disks? Creating and deleting partitions can be done from within &d-i; as well as from an existing operating system. As a rule of thumb, partitions should be created by the system for which they are to be used, i.e. partitions to be used by &debian-gnu; should be created from within &d-i; and partitions to be used from another operating system should be created from there. &d-i; is capable of creating non-&arch-kernel; partitions, and partitions created this way usually work without problems when used in other operating systems, but there are a few rare corner cases in which this could cause problems, so if you want to be sure, use the native partitioning tools to create partitions for use by other operating systems. If you are going to install more than one operating system on the same machine, you should install all other system(s) before proceeding with the &debian; installation. Windows and other OS installations may destroy your ability to start &debian;, or encourage you to reformat non-native partitions. You can recover from these actions or avoid them, but installing the native system first saves you trouble. In order for OpenFirmware to automatically boot &debian-gnu; the &arch-parttype; partitions should appear before all other partitions on the disk, especially Mac OS X boot partitions. This should be kept in mind when pre-partitioning; you should create a &arch-parttype; placeholder partition to come before the other bootable partitions on the disk. (The small partitions dedicated to Apple disk drivers are not bootable.) You can delete the placeholder with the &debian; partition tools later during the actual install, and replace it with &arch-parttype; partitions. &nondeb-part-sparc.xml; &nondeb-part-powerpc.xml;