1FIXPARTS(8) FixParts Manual FIXPARTS(8)
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6 fixparts - MBR partition table repair utility
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9 fixparts device
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13 FixParts (aka fixparts) is a text-mode menu-driven program for repair‐
14 ing certain types of problems with Master Boot Record (MBR) partition
15 tables. The program has three design goals, although a few additional
16 features are supported, as well:
17 * It can remove stray GUID Partition Table (GPT) data, which can
20 be left behind on a disk that was once used as a GPT disk but
21 then incompletely converted to the more common (as of 2011) MBR
22 form.
23 * It can repair mis-sized extended partitions -- either partitions
26 that extend beyond the physical end of the disk or that overlap
27 with nearby primary partitions. FixParts is designed in such a
28 way that this type of repair occurs automatically, so if it's
29 the only problem with your disk, you can launch the program and
30 then immediately save the partition table, making no manual
31 changes, and the program will fix the problem.
32 * You can change primary partitions into logical partitions or
35 vice-versa, within constraints imposed by the MBR data struc‐
36 tures.
37 Additional features include the ability to change partition type codes
40 or boot/active flags, to delete partitions, and to recompute CHS val‐
41 ues. With the possible exception of recomputing CHS values, these sec‐
42 ondary features are better performed with fdisk, because fixparts'
43 design means that it's likely to alter partition numbering even when
44 such changes are not requested.
45 The fixparts program employs a user interface similar to that of
47 Linux's fdisk, but fixparts is much more specialized. Most importantly,
48 you can't create new partitions with fixparts, although you can change
49 primary/logical assignment.
50 In the MBR scheme, partitions come in three varieties:
52 primary
55 These partitions are defined in the first sector of the hard
56 disk and are limited in number to four. Some OSes, such as Win‐
57 dows and FreeBSD, must boot from a primary partition.
58 extended
61 Extended partitions are specialized primary partitions. They
62 serve as holding areas for logical partitions.
63 logical
66 A disk can contain an arbitrary number of logical partitions
67 (fixparts, however, imposes a limit of 124 logical partitions).
68 All the logical partitions reside inside a single extended par‐
69 tition, and are defined using a linked-list data structure. This
70 fact means that every logical partition must be preceded by at
71 least one sector of unallocated space to hold its defining data
72 structure (an Extended Boot Record, or EBR).
73 These distinctions mean that primary and logical partitions cannot be
76 arbitrarily interspersed. A disk can contain one to three primary par‐
77 titions, a block of one or more logical partitions, and one to three
78 more primary partitions (for a total of three primary partitions, not
79 counting the extended partition). Primary partitions may not be sand‐
80 wiched between logical partitions, since this would mean placing a pri‐
81 mary partition within an extended partition (which is just a specific
82 type of primary partition).
83 Unlike most disk utilities, fixparts' user interface ignores extended
85 partitions. Internally, the program discards the information on the
86 original extended partition and, when you tell it to save its changes,
87 it generates a new extended partition to contain the then-defined logi‐
88 cal partitions. This is done because most of the repairs and manipula‐
89 tions the tool performs require generating a fresh extended partition,
90 so keeping the original in the user interface would only be a complica‐
91 tion.
92 Another unusual feature of fixparts' user interface is that partition
94 numbers do not necessarily correlate with primary/logical status. In
95 most utilities, partitions 1-4 correspond to primary partitions,
96 whereas partitions 5 and up are logical partitions. In fixparts, any
97 partition number may be assigned primary or logical status, so long as
98 the rules for layout described earlier are obeyed. When the partition
99 table is saved, partitions will be assigned appropriately and then
100 tools such as the Linux kernel and fdisk will give them conventional
101 numbers.
102 When it first starts, fixparts performs a scan for GPT data. If the
104 disk looks like a conventional GPT disk, fixparts refuses to run. If
105 the disk appears to be a conventional MBR disk but GPT signatures are
106 present in the GPT primary or secondary header areas, fixparts offers
107 to delete this extraneous data. If you tell it to do so, the program
108 immediately wipes the GPT header or headers. (If only one header was
109 found, only that one header will be erased, to minimize the risk of
110 damaging a boot loader or other data that might have overwritten just
111 one of the GPT headers.)
112 With the exception of optionally erasing leftover GPT data when it
114 first starts, fixparts keeps all changes in memory until the user
115 writes changes with the w command. Thus, you can adjust your partitions
116 in the user interface and abort those changes by typing q to quit with‐
117 out saving changes.
118
121 The fixparts utility supports no command-line options, except for spec‐
122 ification of the target device.
123 Most interactions with fixparts occur with its interactive text-mode
125 menu. Specific functions are:
126 a Toggle the active/boot flag. This flag is required by some boot
129 loaders and OSes.
130 c Recompute the cylinder/head/sector (CHS) values for all parti‐
134 tions. CHS addressing mode is largely obsolete, but some OSes
135 and utilities complain if they don't like the CHS values. Note
136 that fixparts' CHS values are likely to be incorrect on disks
137 smaller than about 8 GiB except on Linux.
138 l Change a partition's status to logical. This option will only
141 work if the current partition layout supports such a change.
142 Note that if changing a partition's status in this way is not
143 currently possible, making some other change may make it possi‐
144 ble. For instance, omitting a partition that precedes the target
145 partition may enable converting a partition to logical form if
146 there had been no free sectors between the two partitions.
147 o Omit a partition. Once omitted, the partition will still appear
150 in the fixparts partition list, but it will be flagged as omit‐
151 ted. You can subsequently convert it to primary or logical form
152 with the r or l commands, respectively. When you save your
153 changes with w, though, the partition will be lost.
154 p Display basic partition summary data. This includes partition's
157 number, the boot/active flag's status, starting and ending sec‐
158 tor numbers, primary/logical/omitted status, whether or not the
159 partition may be converted to logical form, and the partition's
160 MBR types code.
161 q Quit from the program without saving your changes. Use this
164 option if you just wanted to view information or if you make a
165 mistake and want to back out of all your changes.
166 r Change a partition's status to primary. This option will only
169 work if the current partition layout supports such a change.
170 Note that every partition can theoretically become a primary
171 partition, although in some configurations, making this change
172 will require omitting some partitions. If fixparts refuses to
173 allow changing a partition to primary, you may need to convert
174 other partitions to logical form or omit them entirely.
175 s Sort partition entries. This option orders partitions in the
178 display to match their on-disk positions, which can make under‐
179 standing the disk layout easier in some cases. This option has
180 no effect on the ultimate ordering of logical partitions, which
181 are sorted before being saved. The order of primary partitions
182 in the final saved partition table may be affected by this
183 option. In both cases, as already noted, the partition numbers
184 displayed by fixparts may not be the same as those used by the
185 kernel or displayed by other partitioning tools.
186 t Change a partition's type code. You enter the type code using a
189 one-byte hexadecimal number.
190 w Write data. Use this command to save your changes and exit from
193 the program.
194 ? Print the menu. Type this command (or any other unrecognized
197 command) to see a summary of available options.
198
201 Known bugs and limitations include:
202 * The program compiles correctly only on Linux, FreeBSD, Mac OS X,
205 and Windows. Linux versions for x86-64 (64-bit), x86 (32-bit),
206 and PowerPC (32-bit) have been tested, with the x86-64 version
207 having seen the most testing. Under FreeBSD, 32-bit (x86) and
208 64-bit (x86-64) versions have been tested. Only 32-bit versions
209 for Mac OS X and Windows have been tested.
210 * The FreeBSD version of the program can't write changes to the
213 partition table to a disk when existing partitions on that disk
214 are mounted. (The same problem exists with many other FreeBSD
215 utilities, such as gpt, fdisk, and dd.) This limitation can be
216 overcome by typing sysctl kern.geom.debugflags=16 at a shell
217 prompt.
218 * The program can load only up to 128 partitions (4 primary parti‐
221 tions and 124 logical partitions). This limit can be raised by
222 changing the #define MAX_MBR_PARTS line in the basicmbr.h source
223 code file and recompiling.
224 * The program can read partitions only if the disk has correct LBA
227 partition descriptors. These descriptors should be present on
228 any disk over 8 GiB in size or on smaller disks partitioned with
229 any but very ancient software.
230 * The program makes no effort to preserve partition numbers. This
233 can have consequences for boot loaders and for mounting filesys‐
234 tems via /etc/fstab. It may be necessary to edit configuration
235 files or even to re-install your boot loader.
236 *
239 The program may change the order of partitions in the partition
241 table.
242
245 Primary author: Roderick W. Smith (rodsmith@rodsbooks.com)
246 Contributors:
248 * Yves Blusseau (1otnwmz02@sneakemail.com)
250 * David Hubbard (david.c.hubbard@gmail.com)
252 * Justin Maggard (justin.maggard@netgear.com)
254 * Dwight Schauer (dschauer@gmail.com)
256 * Florian Zumbiehl (florz@florz.de)
258
262 cfdisk (8), cgdisk (8), fdisk (8), mkfs (8), parted (8), sfdisk (8)
263 gdisk (8) sgdisk (8)
264 http://en.wikipedia.org/wiki/Master_boot_record
266 http://www.rodsbooks.com/fixparts/
268
271 The fixparts command is part of the GPT fdisk package and is available
272 from Rod Smith.
273Roderick W. Smith 1.0.3 FIXPARTS(8)