Index Index for
Section 8
Index Alphabetical
listing for C
Bottom of page Bottom of
page		 

chvol(8)


NAME

  chvol - Changes the attributes of a volume


SYNOPSIS

  /sbin/chvol [-l] [-r blocks] [-w blocks] [-t blocks] [-c on | off] [-A]
  special domain


OPTIONS

  -A  Activates a volume after an incomplete addvol or rmvol operation.

  -c on | off
      Turns I/O consolidation mode on or off.

  -l  Displays the range of I/O transfer sizes, in 512-byte blocks, as
      calculated by the kernel, based on the disk's geometry:

      rblks displays the minimum, the maximum, and the preferred transfer
      size for reads.

      wblks displays the minimum, the maximum, and the preferred transfer
      size for writes.

  -r blocks
      Specifies the maximum number of 512-byte blocks that the file system
      reads from the disk at one time.

  -t blocks
      If smoothsync is enabled on the domain (smoothsync_age is non-zero),
      this switch should not be used as the smoothsync algorithms make its
      use obsolete. If smoothsync is not enabled on the domain, this switch
      specifies how many 512-byte blocks of dirty data will be cached in
      memory for this volume before they are written to permanent storage.
      The current value of this variable is the output value thresh
      (threshold). The number of blocks specified must be in multiples of 16.
      The valid range is 0-32768. The default (when a volume is added to a
      domain) is 16384.

  -w blocks
      Specifies the maximum number of 512-byte blocks that the file system
      writes to the disk at one time.


OPERANDS

  special
      Specifies the block special device name, such as /dev/disk/dsk2c. This
      command supports shorthand device names for block special devices. For
      example, if you enter dsk2g, it will be translated to /dev/disk/dsk2g.

  domain
      Specifies the name of the domain.


DESCRIPTION

  The chvol command can be run at anytime to change the attributes of a
  volume in an active domain; the system does not have to be quiescent. If
  you attempt to change the attributes of a volume in a domain that is not
  active, an error message is produced.

  The initial I/O transfer parameter for both reads and writes is typically
  128 or 256 blocks, depending on the disk driver's preferred I/O transfer
  rate.	 Once you change the I/O transfer parameters with the -r option or
  the -w option, the parameters remain fixed until you change them again. The
  values for the I/O transfer parameters are limited by the device driver.
  Every device has a minimum and maximum value for the size of the reads and
  writes it can handle. If you set a value that is outside of the range that
  the device driver allows, the device automatically resets the value to the
  largest or smallest it can handle.

  By default, the I/O consolidation mode (cmode) is on.	 The cmode must be on
  for the I/O transfer parameters to take effect. You can use the -c option
  to turn the cmode off, which sets the I/O transfer parameter to one page.

  Interrupting an rmvol operation can leave the volume in an inaccessible
  state. If a volume does not allow new allocations after an rmvol operation,
  use the chvol command with the -A option to reactivate the volume.

  Using the chvol command without any options displays the current cmode and
  the I/O transfer parameters.


NOTES

  This command supports shorthand names for LSM volume names. For example, if
  you enter the following:

       # chvol testdg.vol1 dom1

  the volume name will be translated to:

       # chvol /dev/vol/testdg/vol1 dom1


RESTRICTIONS

  The values for the wblks and rblks attributes are limited by the device
  driver.

  You must be the root user to use this command.


EXAMPLES

   1.  The following example displays the cmode and the I/O transfer
       parameters of the /dev/disk/dsk1c volume in the domain1 domain:
	    # chvol /dev/disk/dsk1c domain1
	    rblks = 128	 wblks = 128  cmode = on thresh = 16,384

   2.  The following example additionally toggles the cmode:
	    # chvol -c off /dev/disk/dsk1c domain1
	    # chvol /dev/disk/dsk1c domain1
	    rblks = 128	 wblks = 128  cmode = off thresh = 16,384

   3.  The following example continues by changing the I/O transfer
       parameters of reads (rblks) and writes (wblks) from 128 blocks to 256
       blocks.	Note that the cmode is off and must be on before the
       parameters take effect:
	    # chvol -r 256 -w 256 -c on /dev/disk/dsk1c domain1
	    chvol /dev/disk/dsk1c domain1
	    rblks = 256	 wblks = 256  cmode = on thresh = 16,384

   4.  The following example shows the I/O transfer range on domain1:
	    # chvol -l /dev/disk/dsk0a domain1
	    chvol /dev/disk/dsk0a domain1
	    rblks: min = 16  max = 32768  pref = 256
	    wblks: min = 16  max = 32768  pref = 256


SEE ALSO

  Command: showfdmn(8)

  Files: advfs(4)

Index Index for
Section 8
Index Alphabetical
listing for C
Top of page Top of
page