Document soft updates journaling and GEOM-based UFS journaling.
Reviewed by: mckusick
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Hiroki Sato
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639eac2087
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0e31d5241d
@ -30,7 +30,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 26, 2001
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.Dd August 25, 2019
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.Dt FFS 7
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.Os
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.Sh NAME
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@ -46,6 +46,7 @@ In the kernel configuration file:
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.Cd "options UFS_DIRHASH"
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.Cd "options UFS_EXTATTR"
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.Cd "options UFS_EXTATTR_AUTOSTART"
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.Cd "options UFS_GJOURNAL"
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.Pp
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In
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.Xr fstab 5 :
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@ -84,20 +85,65 @@ and enforces metadata update dependencies
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(e.g., updating free block maps)
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to ensure that the file system remains consistent.
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.Pp
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To enable soft updates on an
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.Em unmounted
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file system, use the following command:
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To create a new file system with the soft updates
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enabled,
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use
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.Xr newfs 8
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command:
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.Pp
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.D1 Nm tunefs Fl n Cm enable Ar fs
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.D1 Nm newfs Fl U Ar fs
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.Pp
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.Ar fs
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can be either a mount point listed in
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.Xr fstab 5
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(e.g.,
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.Pa /usr ) ,
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.Pq e.g. , Pa /usr ,
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or a disk device
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(e.g.,
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.Pa /dev/da0a ) .
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.Pq e.g., Pa /dev/da0a .
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.Pp
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It is possible to enable soft updates on an
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.Em unmounted
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file system by using
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.Xr tunefs 8
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command:
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.Pp
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.D1 Nm tunefs Fl n Cm enable Ar fs
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.Pp
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Soft updates can also add journaling that reduces the time spent by
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.Xr fsck_ffs 8
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cleaning up a filesystem after a crash from several minutes to a few seconds.
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The journal is placed in an inode named
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.Pa .sujournal ,
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and is kept as a circular log of segments containing
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records that describe metadata operations.
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.Pp
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To create a new file system with both the soft updates
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and soft updates journaling enabled,
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use the following command:
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.Pp
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.D1 Nm newfs Fl j Ar fs
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.Pp
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This runs
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.Xr tunefs 8
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command after
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.Xr newfs 8
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command with
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.Fl U
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flag enabled.
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It is possible to enable soft updates journaling on an
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.Em unmounted
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file system by using
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.Xr tunefs 8
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command:
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.Pp
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.D1 Nm tunefs Fl j Cm enable Ar fs
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.Pp
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This flag automatically enables the soft updates feature
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when it is not enabled.
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Note that this
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.Xr tunefs 8
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command will fail if a file
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.Pa .sujournal
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already exists before enabling the soft updates journaling.
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.El
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.Ss File Ownership Inheritance
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.Bl -tag -width 2n
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@ -155,10 +201,9 @@ extattrctl initattr -p / 388 posix1e.acl_default
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.Ed
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.Pp
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On the next mount of the root file system,
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the attributes will be automatically started
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(if
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the attributes will be automatically started if
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.Dv UFS_EXTATTR_AUTOSTART
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is included in the kernel configuration),
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is included in the kernel configuration,
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and ACLs will be enabled.
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.Ss Directory Hashing
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.Bl -tag -width 2n
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@ -183,7 +228,52 @@ subdirectory of the file system root during the mount operation.
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If found, extended attribute support will be
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automatically started for that file system.
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.El
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.Ss GEOM-based Journaling
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.Bl -tag -width 2n
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.It Cd "options UFS_GJOURNAL"
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Implements a block level journaling of a UFS file system,
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which is for both data and metadata.
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To enable this,
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create a
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.Xr gjournal 8
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GEOM provider for a block device by using the
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following command:
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.Pp
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.D1 Nm gjournal label Ar da0
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.Pp
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In this example,
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.Pa /dev/da0
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is used as the target block device,
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and
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.Pa /dev/da0.journal
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is created.
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Then create a new file system by using
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.Xr newfs 8
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with the block level journaling flag and mount it:
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.Pp
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.D1 Nm newfs Fl J Ar /dev/da0.journal
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.D1 Nm mount Fl o Cm async Ar /dev/da0.journal Ar /mnt
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.Pp
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.Cm async
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option is not mandatory but recommended for better performance
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because the journaling guarantees the consistency of an
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.Cm async
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mount.
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.Pp
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It is also possible to enable the block level journaling
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on an existing file system.
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To do so,
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use
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.Xr gjournal 8
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utility to label the underlying block device and
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.Xr tunefs 8
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utility to enable the block level journaling flag:
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.Pp
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.D1 Nm gjournal label Ar da0
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.D1 Nm tunefs Fl J Cm enable Ar /dev/da0.journal
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.D1 Nm mount Fl o Cm async Ar /dev/da0.journal Ar /mnt
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.El
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.Ss Xr sysctl 8 MIBs
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The following
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.Xr sysctl 8
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MIBs are defined for use with
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@ -192,11 +282,11 @@ MIBs are defined for use with
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.It Va vfs.ffs.doasyncfree
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Asynchronously write out modified i-node and indirect blocks
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upon reallocating file system blocks to be contiguous.
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(Default: 1.)
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.Pq Default: 1 .
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.It Va vfs.ffs.doreallocblks
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Enable support for the rearrangement of blocks
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to be contiguous.
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(Default: 1.)
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.Pq Default: 1 .
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.El
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.Sh SEE ALSO
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.Xr quota 1 ,
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@ -204,7 +294,9 @@ to be contiguous.
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.Xr extattr 3 ,
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.Xr edquota 8 ,
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.Xr extattrctl 8 ,
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.Xr sysctl 8
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.Xr fsck_ffs 8 ,
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.Xr sysctl 8 ,
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.Xr tunefs 8
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.Rs
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.%A M. McKusick
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.%A W. Joy
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@ -224,3 +316,10 @@ to be contiguous.
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.%J "Proceedings of the Freenix Track at the 1999 Usenix Annual Technical Conference"
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.%P 71-84
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.Re
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.Rs
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.%A M. McKusick
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.%A J. Roberson
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.%D May 2010
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.%T "Journaled Soft-updates"
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.%J "BSD Canada Conference 2010 (BSDCan)"
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.Re
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