145 lines
4.0 KiB
Groff
145 lines
4.0 KiB
Groff
.\" $NetBSD: resize_ffs.8,v 1.18 2017/10/01 22:59:19 christos Exp $
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.\"
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.\" As its sole author, I explicitly place this man page in the public
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.\" domain. Anyone may use it in any way for any purpose (though I would
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.\" appreciate credit where it is due).
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.\"
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.\" /~\ The ASCII der Mouse
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.\" \ / Ribbon Campaign
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.\" X Against HTML mouse@rodents.montreal.qc.ca
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.\" / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
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.\"
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.Dd October 1, 2017
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.Dt RESIZE_FFS 8
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.Os
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.Sh NAME
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.Nm resize_ffs
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.Nd resize a file system on disk or in a file
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.Sh SYNOPSIS
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.Nm
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.Op Fl cpvy
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.Op Fl s Ar size
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.Ar special
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.Sh DESCRIPTION
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.Nm
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resizes a file system.
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.Ar special
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is the name of the raw disk device or file where the file system resides.
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.Nm
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can both grow and shrink file systems.
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When growing, the disk device
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must of course be large enough to contain the new file system;
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.Nm
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simply extends the file system data structures into the new space.
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When shrinking,
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.Nm
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assumes this.
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.Nm
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has to copy anything that currently resides in the space being shrunk
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away; there must be enough space free on the file system for this to
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succeed.
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If there is not,
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.Nm
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will complain and exit; when this happens, it attempts to always leave
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the file system in a consistent state, but it is probably a good idea to
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check the file system with
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.Xr fsck 8 .
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.Pp
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If no
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.Fl s
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option is provided,
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.Nm
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will grow the file system to the underlying device size which is
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determined from
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.Ar special .
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl c
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Check to see if the new size would change the file system.
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No changes will be made to the file system.
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.It Fl p
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Display a progress meter during the resize process.
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.It Fl s
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Specify the file system size to which the file system should be
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resized.
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The size is given as the count of disk sectors, usually 512 bytes.
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It will not work correctly for file systems with other sector sizes.
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To see the
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exact value, have a look at the disk specification or the disklabel.
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Mostly used to shrink file systems.
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.It Fl v
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Be more verbose.
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.It Fl y
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Disable sanity questions made by
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.Nm .
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.El
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.Sh WARNING
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.Em Interrupting
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.Nm
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.Em "may leave your file system in an inconsistent state and require a"
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.Em "restore from backup."
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It attempts to write in the proper order to avoid problems, but as it is
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still considered experimental, you should take great care when using it.
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.Pp
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When
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.Nm
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is applied to a consistent file system, it should always produce a
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consistent file system; if the file system is not consistent to start
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with,
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.Nm
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may misbehave, anything from dumping core to completely curdling the
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data.
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It is probably wise to
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.Xr fsck 8
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the file system before and after, just to be safe.
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You should be aware that just because
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.Xr fsck 8
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is happy with the file system does not mean it is intact.
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.Sh EXIT STATUS
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.Nm
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exits with 0 on success.
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Any major problems will cause
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.Nm
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to exit with the non-zero
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.Xr exit 3
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codes, so as to alert any invoking program or script that human
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intervention is required.
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.Sh EXAMPLES
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.Dl resize_ffs Cm /dev/vg00/rlv1
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.Pp
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will enlarge the file system on the Logical Volume
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.Pa /dev/vg00/lv1
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from Volume Group vg00 to the current device size.
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.Sh SEE ALSO
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.Xr fs 5 ,
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.Xr fsck 8 ,
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.Xr newfs 8
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.Sh HISTORY
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The
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.Nm
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command first appeared in
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.Nx 2.0 .
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.Sh AUTHORS
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.An der Mouse
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.Aq mouse@rodents.montreal.qc.ca
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(primary author)
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.An Jeff Rizzo
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.Aq riz@NetBSD.org
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(Byteswapped file system and UFS2 support)
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.Pp
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A big bug-finding kudos goes to John Kohl for finding a significant
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rotational layout bug.
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.Sh BUGS
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Can fail to shrink a file system when there actually is enough space,
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because it does not distinguish between a block allocated as a block
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and a block fully occupied by two or more frags.
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This is unlikely to
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occur in practice; except for pathological cases, it can happen only
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when the new size is extremely close to the minimum possible.
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.Pp
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Has no intelligence whatever when it comes to allocating blocks to copy
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data into when shrinking.
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.Pp
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Does not currently support shrinking FFSv2 file systems.
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