1.\" $NetBSD: resize_ffs.8,v 1.10 2011/01/05 02:18:15 riz Exp $ 2.\" 3.\" As its sole author, I explicitly place this man page in the public 4.\" domain. Anyone may use it in any way for any purpose (though I would 5.\" appreciate credit where it is due). 6.\" 7.\" /~\ The ASCII der Mouse 8.\" \ / Ribbon Campaign 9.\" X Against HTML mouse@rodents.montreal.qc.ca 10.\" / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B 11.\" 12.Dd January 4, 2011 13.Dt RESIZE_FFS 8 14.Os 15.Sh NAME 16.Nm resize_ffs 17.Nd resize a file system on disk or in a file 18.Sh SYNOPSIS 19.Nm 20.Op Fl y 21.Op Fl s Ar size 22.Ar special 23.Sh DESCRIPTION 24.Nm 25resizes a file system. 26.Ar special 27is the name of the raw disk device or file where the file system resides; 28(Sectors are almost always 512 bytes, and 29.Nm 30can both grow and shrink file systems. 31When growing, the disk device 32must of course be large enough to contain the new file system; 33.Nm 34simply extends the file system data structures into the new space. 35When shrinking, 36.Nm 37assumes this. 38It will not work correctly for file systems with other sector sizes.) 39.Nm 40has to copy anything that currently resides in the space being shrunk 41away; there must be enough space free on the file system for this to 42succeed. 43If there isn't, 44.Nm 45will complain and exit; when this happens, it attempts to always leave 46the file system in a consistent state, but it is probably a good idea to 47check the file system with 48.Xr fsck 8 . 49.Pp 50If no 51.Fl s 52option is provided, 53.Nm 54will grow the file system to the underlying device size which is 55determined from 56.Ar special . 57.Pp 58The options are as follows: 59.Bl -tag -width indent 60.It Fl s 61Specify the file system size to which the file system should be 62resized. 63Mostly used to shrink file systems. 64.It Fl y 65Disable sanity questions made by 66.Nm . 67.El 68.Sh WARNING 69.Em Interrupting 70.Nm 71.Em "may leave your file system in an inconsistent state and require a" 72.Em "restore from backup." 73It attempts to write in the proper order to avoid problems, but as it is 74still considered experimental, you should take great care when using it. 75.Pp 76When 77.Nm 78is applied to a consistent file system, it should always produce a 79consistent file system; if the file system is not consistent to start 80with, 81.Nm 82may misbehave, anything from dumping core to completely curdling the 83data. 84It's probably wise to 85.Xr fsck 8 86the file system before and after, just to be safe. 87You should be aware that just because 88.Xr fsck 8 89is happy with the file system does not mean it is intact. 90.Sh EXIT STATUS 91.Nm 92exits with 0 on success. 93Any major problems will cause 94.Nm 95to exit with the non-zero 96.Xr exit 3 97codes, so as to alert any invoking program or script that human 98intervention is required. 99.Sh EXAMPLES 100.Dl resize_ffs Cm /dev/vg00/rlv1 101.Pp 102will enlarge the file system on the Logical Volume 103.Pa /dev/vg00/lv1 104from Volume Group vg00 to the current device size. 105.Sh SEE ALSO 106.Xr fs 5 , 107.Xr fsck 8 , 108.Xr newfs 8 109.Sh HISTORY 110The 111.Nm 112command first appeared in 113.Nx 2.0 . 114.Sh AUTHORS 115.An der Mouse 116.Aq mouse@rodents.montreal.qc.ca 117(primary author) 118.An Jeff Rizzo 119.Aq riz@NetBSD.org 120(Byteswapped file system and UFS2 support) 121.Pp 122A big bug-finding kudos goes to John Kohl for finding the rotational 123layout bug referred to in the 124.Sx WARNING 125section above. 126.Sh BUGS 127Can fail to shrink a file system when there actually is enough space, 128because it does not distinguish between a block allocated as a block 129and a block fully occupied by two or more frags. 130This is unlikely to 131occur in practice; except for pathological cases, it can happen only 132when the new size is extremely close to the minimum possible. 133.Pp 134Has no intelligence whatever when it comes to allocating blocks to copy 135data into when shrinking. 136.Pp 137Doesn't currently support shrinking FFSv2 file systems. 138