Date: Mon, 6 Jun 2011 21:02:26 +0000 (UTC) From: Gavin Atkinson <gavin@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r222778 - head/sbin/geom/class/part Message-ID: <201106062102.p56L2QsC048171@svn.freebsd.org>
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Author: gavin Date: Mon Jun 6 21:02:26 2011 New Revision: 222778 URL: http://svn.freebsd.org/changeset/base/222778 Log: Rework parts of this man page to improve grammar. Inspired by, and parts submitted by... PR: docs/157467 Submitted by: Ben Kaduk <kaduk mit.edu> MFC after: 2 weeks Modified: head/sbin/geom/class/part/gpart.8 Modified: head/sbin/geom/class/part/gpart.8 ============================================================================== --- head/sbin/geom/class/part/gpart.8 Mon Jun 6 20:58:15 2011 (r222777) +++ head/sbin/geom/class/part/gpart.8 Mon Jun 6 21:02:26 2011 (r222778) @@ -24,7 +24,7 @@ .\" .\" $FreeBSD$ .\" -.Dd May 30, 2011 +.Dd June 6, 2011 .Dt GPART 8 .Os .Sh NAME @@ -530,16 +530,17 @@ about its use. .El .\" .Sh PARTITION TYPES +Partition types are identified on disk by particular strings or magic +values. The .Nm -utility uses symbolic names for common partition types to avoid that the -user needs to know what the partitioning scheme in question is and what -the actual number or identification needs to be used for a particular -type. +utility uses symbolic names for common partition types to avoid the +user needing to know these values or other details of the partitioning +scheme in question. The .Nm utility also allows the user to specify scheme-specific partition types -for partition types that do not have symbol names. +for partition types that do not have symbolic names. The symbolic names currently understood are: .Bl -tag -width ".Cm freebsd-vinum" .It Cm bios-boot @@ -740,30 +741,30 @@ action or reverted with the .Cm undo action. .Sh RECOVERING -The GEOM class PART supports recovering of partition tables only for GPT. +The GEOM PART class supports recovering of partition tables only for GPT. The GUID partition table has a primary and secondary (backup) copy of -metadata for redundance. -They are stored in the begining and in the end of device respectively. -Therefore it is acceptable to have some corruptions in the metadata that -are not fatal to work with GPT. -When kernel detects corrupt metadata it marks this table as corrupt and -reports about corruption. -Any changes in corrupt table are prohibited except +metadata for redundance, these are stored at the begining and the end +of the device respectively. +As a result of having two copies, it is acceptable to have some corruption +within the metadata that is not fatal to the working of GPT. +When the kernel detects corrupt metadata it marks this table as corrupt and +reports the corruption. +Any operations on corrupt tables are prohibited except for .Cm destroy and .Cm recover . .Pp -In case when only first sector is corrupt kernel can not detect GPT even -if partition table is not corrupt. -You can write protective MBR with +If the first sector of a provider is corrupt, the kernel can not detect GPT +even if partition table itself is not corrupt. +You can rewrite the protective MBR using the .Xr dd 1 -command to restore ability of GPT detection. -The copy of protective MBR is usually located in the +command, to restore the ability to detect the GPT. +The copy of the protective MBR is usually located in the .Pa /boot/pmbr file. .Pp -In case when some of metadata is corrupt you will get to know about this -from kernel's messages like these: +If one GPT header appears to be corrupt but the other copy remains intact, +the kernel will log the following: .Bd -literal -offset indent GEOM: provider: the primary GPT table is corrupt or invalid. GEOM: provider: using the secondary instead -- recovery strongly advised. @@ -777,32 +778,31 @@ GEOM: provider: using the primary only - .Pp Also .Nm -commands like +commands such as .Cm show , status and .Cm list -will report about corrupt table. +will report about corrupt tables. .Pp -In case when the size of device has changed (e.g.\& volume expansion) the -secondary GPT header will become located not in the last sector. +If the size of the device has changed (e.g.\& volume expansion) the +secondary GPT header will no longer be located in the last sector. This is not a metadata corruption, but it is dangerous because any -corruption of the primary GPT will lead to lost of partition table. -Kernel reports about this problem with message: +corruption of the primary GPT will lead to loss of partition table. +This problem is reported by the kernel with the message: .Bd -literal -offset indent GEOM: provider: the secondary GPT header is not in the last LBA. .Ed .Pp -A corrupt table can be recovered with +This situation can be recovered with the .Cm recover command. -This command does reconstruction of corrupt metadata using -known valid metadata. -Also it can relocate secondary GPT to the end of device. +This command reconstructs the corrupt metadata using known valid +metadata and relocates the secondary GPT to the end of the device. .Pp .Em NOTE : -The GEOM class PART can detect the same partition table on different GEOM -providers and some of them will be marked as corrupt. -Be careful when choosing a provider for recovering. +The GEOM PART class can detect the same partition table visible through +different GEOM providers, and some of them will be marked as corrupt. +Be careful when choosing a provider for recovery. If you choose incorrectly you can destroy the metadata of another GEOM class, e.g.\& GEOM MIRROR or GEOM LABEL. .Sh SYSCTL VARIABLES @@ -815,11 +815,11 @@ The default value is shown next to each .Bl -tag -width indent .It Va kern.geom.part.check_integrity : No 1 This variable controls the behaviour of metadata integrity checks. -When integrity checks are enabled +When integrity checks are enabled, the .Nm PART -GEOM class verifies all generic partition parameters that it gets from the +GEOM class verifies all generic partition parameters obtained from the disk metadata. -If some inconsistency is detected, partition table will be +If some inconsistency is detected, the partition table will be rejected with a diagnostic message: .Sy "GEOM_PART: Integrity check failed (provider, scheme)" . .El
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