Describe the default values for useful options.
Clarify which options are no longer useful.
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063d580388
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=44648
@ -30,7 +30,7 @@
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.\" SUCH DAMAGE.
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.\" SUCH DAMAGE.
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.\"
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.\"
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.\" @(#)newfs.8 8.6 (Berkeley) 5/3/95
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.\" @(#)newfs.8 8.6 (Berkeley) 5/3/95
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.\" $Id: newfs.8,v 1.19 1998/11/28 09:59:40 rnordier Exp $
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.\" $Id: newfs.8,v 1.20 1998/11/29 13:09:01 bde Exp $
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.\"
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.\"
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.Dd May 3, 1995
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.Dd May 3, 1995
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.Dt NEWFS 8
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.Dt NEWFS 8
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@ -162,15 +162,21 @@ See
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.Xr tunefs 8
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.Xr tunefs 8
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for more details on how to set this option.
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for more details on how to set this option.
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.It Fl b Ar block-size
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.It Fl b Ar block-size
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The block size of the file system, in bytes.
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The block size of the file system, in bytes. It must be a power of 2. The
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default size is 8192 bytes, and the smallest allowable size is 4096 bytes.
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.It Fl c Ar #cylinders/group
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.It Fl c Ar #cylinders/group
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The number of cylinders per cylinder group in a file system.
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The number of cylinders per cylinder group in a file system. The default value
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The default value is 16.
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is 16. The maximum value is dependent on a number of other parameters, in
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particular the block size. The best way to find the maximum value for a
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specific file system is to attempt to specify a value which is far too large:
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.Nm
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will print out the maximum value.
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.It Fl d Ar rotdelay
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.It Fl d Ar rotdelay
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Specify the expected time (in milliseconds) to service a transfer
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This parameter once specified the minimum time in milliseconds required to
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completion interrupt and initiate a new transfer on the same disk.
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initiate another disk transfer on the same cylinder. It was used in determining
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The default is 0 milliseconds.
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the rotationally optimal layout for disk blocks within a file. Modern disks
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See
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with read/write-behind achieve higher performance with this feature disabled, so
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this value should be left at the default value of 0 milliseconds. See
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.Xr tunefs 8
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.Xr tunefs 8
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for more details on how to set this option.
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for more details on how to set this option.
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.ne 1i
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.ne 1i
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@ -183,13 +189,19 @@ See
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.Xr tunefs 8
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.Xr tunefs 8
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for more details on how to set this option.
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for more details on how to set this option.
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.It Fl f Ar frag-size
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.It Fl f Ar frag-size
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The fragment size of the file system in bytes.
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The fragment size of the file system in bytes. It must be a power of two
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ranging in value between
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.Ar blocksize/8
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and
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.Ar blocksize .
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The default is 1024 bytes.
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The default is 1024 bytes.
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.It Fl i Ar number of bytes per inode
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.It Fl i Ar number of bytes per inode
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Specify the density of inodes in the file system.
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Specify the density of inodes in the file system.
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The default is to create an inode for every (4 * frag-size) bytes of data space.
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The default is to create an inode for every (4 * frag-size) bytes of data space.
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If fewer inodes are desired, a larger number should be used;
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If fewer inodes are desired, a larger number should be used;
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to create more inodes a smaller number should be given.
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to create more inodes a smaller number should be given.
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One inode is required for each distinct file, so this value effectively
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specifies the average file size on the file system.
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.It Fl m Ar free space \&%
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.It Fl m Ar free space \&%
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The percentage of space reserved from normal users; the minimum free
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The percentage of space reserved from normal users; the minimum free
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space threshold.
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space threshold.
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@ -203,9 +215,14 @@ See
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.Xr tunefs 8
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.Xr tunefs 8
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for more details on how to set this option.
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for more details on how to set this option.
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.It Fl n Ar number of distinguished rotational positions
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.It Fl n Ar number of distinguished rotational positions
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Determine how many rotational time slots there are in one revolution of
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UFS has the ability to keep track of the availability of blocks at different
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the disk. Defaults to 1, which essentially disables the rotational position
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rotational positions, so that it could lay out the data to be picked up with
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table.
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minimum rotational latency. This parameter specifies the default number of
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rotational positions to distinguish.
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.Pp
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Nowadays this value should be set to 1 (which essentially disables the
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rotational position table) because modern drives with read-ahead and
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write-behind do better without the rotational position table.
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.It Fl o Ar optimization\ preference
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.It Fl o Ar optimization\ preference
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.Pq ``space'' or ``time''
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.Pq ``space'' or ``time''
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The file system can either be instructed to try to minimize the time spent
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The file system can either be instructed to try to minimize the time spent
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@ -218,7 +235,12 @@ See
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.Xr tunefs 8
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.Xr tunefs 8
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for more details on how to set this option.
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for more details on how to set this option.
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.It Fl s Ar size
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.It Fl s Ar size
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The size of the file system in sectors.
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The size of the file system in sectors. This value defaults to the size of the
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raw partition specified in
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.Ar special
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(in other words,
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.Nm
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will use the entire partition for the file system).
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.It Fl v
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.It Fl v
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Specify that the disk does not contain any partitions, and that
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Specify that the disk does not contain any partitions, and that
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.Nm
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.Nm
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@ -246,6 +268,8 @@ Used to describe perturbations in the media format to compensate for
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a slow controller.
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a slow controller.
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Track skew is the offset of sector 0 on track N relative to sector 0
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Track skew is the offset of sector 0 on track N relative to sector 0
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on track N-1 on the same cylinder.
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on track N-1 on the same cylinder.
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This option is of historical importance only; modern controllers are always fast
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enough to handle operations back-to-back.
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.It Fl l Ar hardware sector interleave
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.It Fl l Ar hardware sector interleave
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Used to describe perturbations in the media format to compensate for
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Used to describe perturbations in the media format to compensate for
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a slow controller.
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a slow controller.
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@ -254,14 +278,19 @@ specified as the denominator of the ratio:
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.Dl sectors read/sectors passed over
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.Dl sectors read/sectors passed over
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Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies
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Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies
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logical sector 0 is separated by one sector from logical sector 1.
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logical sector 0 is separated by one sector from logical sector 1.
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This option is of historical importance only; the physical sector layout of
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modern disks is not visible from outside.
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.It Fl p Ar spare sectors per track
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.It Fl p Ar spare sectors per track
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Spare sectors (bad sector replacements) are physical sectors that occupy
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Spare sectors (bad sector replacements) are physical sectors that occupy
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space at the end of each track.
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space at the end of each track.
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They are not counted as part of the sectors/track
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They are not counted as part of the sectors/track
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.Pq Fl u
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.Pq Fl u
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since they are not available to the file system for data allocation.
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since they are not available to the file system for data allocation.
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This option is of historical importance only. Modern disks perform their own
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bad sector allocation.
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.It Fl r Ar revolutions/minute
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.It Fl r Ar revolutions/minute
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The speed of the disk in revolutions per minute.
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The speed of the disk in revolutions per minute. This value is no longer of
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interest, since all the parameters which depend on it are usually disabled.
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.ne 1i
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.ne 1i
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.It Fl t Ar #tracks/cylinder
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.It Fl t Ar #tracks/cylinder
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The number of tracks/cylinder available for data allocation by the file
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The number of tracks/cylinder available for data allocation by the file
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@ -284,6 +313,8 @@ They are deducted from the sectors/track
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.Pq Fl u
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.Pq Fl u
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of the last track of each cylinder since they are not available to the file
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of the last track of each cylinder since they are not available to the file
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system for data allocation.
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system for data allocation.
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This option is of historical importance only. Modern disks perform their own
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bad sector allocation.
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.El
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.El
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.Pp
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.Pp
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The options to the
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The options to the
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