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voldisk(8)							    voldisk(8)

NAME
       voldisk - Defines and manages Logical Storage Manager disks

SYNOPSIS
       /sbin/voldisk [-f] init accessname [attribute...]

       /sbin/voldisk [-f] define accessname [attribute...]

       /sbin/voldisk offline accessname...

       /sbin/voldisk online accessname...

       /sbin/voldisk [-a] online

       /sbin/voldisk rm accessname...

       /sbin/voldisk [-g diskgroup] [-qs] list [disk...]

       /sbin/voldisk clearimport accessname...

       /sbin/voldisk [-g diskgroup] check disk...

       /sbin/voldisk [-g diskgroup] set	 disk [attribute...]

       /sbin/voldisk moddb accessname [attribute...]

OPTIONS
       Forces  an  operation  that  would normally fail.  Specifies all online
       disks that are not currently in an imported disk group.	Specifies  the
       disk  group  for the operation.	Suppresses the listing of output field
       labels.	Specifies the listing of detailed information  from  the  disk
       header,	including  the	disk ID, host ID, disk group ID and disk group
       name.

DESCRIPTION
       The voldisk utility performs basic administrative operations on	disks.
       Operations  include initializing and replacing disks, as well as taking
       care of some bookkeeping necessary for the disk model presented by  the
       Logical Storage Manager.

       The  voldisk  operations	 that  take an accessname argument accept only
       disk access names, which are system-specific names that relate to  disk
       addresses.  On Tru64 UNIX systems, disk access names are usually of the
       form dsknp, where dsk is the device mnemonic for disk devices, n is the
       sequence	 number of the disk, and p is the partition identifier (in the
       range a to h). Special devices, such as internal	 RAM  disks,  may  use
       different  forms	 for  disk  access  names.  Disk  access  names relate
       directly to device node names in the /dev/disk directory.

       The voldisk operations that take a disk argument can take  disk	access
       names  or  disk media names (for example, disk01). For such operations,
       you can specify a disk group with -g to distinguish  disk  media	 names
       that are used in more than one disk group.

       Physical	 disks	in the Logical Storage Manager are presumed to be mov‐
       able, and are usually identified by a unique  disk  ID  stored  on  the
       physical	 disk, rather than by a disk device node. This allows disks to
       be moved to different SCSI target IDs without affecting correct	opera‐
       tion.

       The  Logical Storage Manager maintains known disk device address infor‐
       mation in a set of disk access records, which are stored in the	rootdg
       disk  group  configuration. The names of these records are based on the
       disk access name. These disk access records are normally used solely to
       identify	 which	physical  disks exist, based on disk IDs stored on the
       disks themselves.   All	voldisk	 operations  except  init  and	define
       require specification of defined disk access records.

   Private Region Data Structures
       Physical	 disks	contain	 public regions, which are used for allocating
       subdisks. They can also contain private regions,	 which	are  used  for
       storing	private	 Logical  Storage Manager information. Private regions
       are structured regions, and are	maintained  entirely  by  the  Logical
       Storage Manager.

       Private regions contain the following structures: Disk header

	      Each  private  region  contains  exactly	two  copies  of a disk
	      header, which defines the unique disk ID, disk geometry informa‐
	      tion,  and  disk	group  association information. Two copies are
	      created so that one copy can be lost (due to I/O failures) with‐
	      out  causing use of the disk to be lost. The primary copy of the
	      disk header is stored in block 0	of  the	 private  region.  The
	      alternate	 copy  is  stored within the first 256 sectors. If the
	      primary copy is unreadable or unusable, the Logical Storage Man‐
	      ager will search the first 256 sectors of the private region for
	      the alternate copy.  Table of contents

	      A linked list of blocks, pointed to by  the  disk	 header,  that
	      define  additional structures in the private and public regions.
	      The table of contents blocks  define  disk  group	 configuration
	      copy  locations, log copy locations, and reserved regions carved
	      from the public region. Each link block in the table of contents
	      is  replicated  at  the beginning and end of the private region.
	      If the primary copy of any one link block is unreadable or unus‐
	      able,  the  alternate  copy of that link is used.	 Configuration
	      copies

	      A disk contains 0, 1, or	2  disk	 group	configuration  copies,
	      depending	 on the number specified when the disk was initialized
	      using the voldisk init operation (explained later). The  default
	      number of copies is 1. When a disk is added to a disk group, the
	      disk group's persistent configuration  records  are  written  to
	      each  copy. For disks that are not associated with a disk group,
	      the space allocated for configuration copies is unused.

	      Each disk group requires at least one usable configuration copy.
	      Preferably  there	 should	 be  at	 least	four copies, allocated
	      between at least two disks.  This allows one  disk  to  be  lost
	      totally, while still preserving sufficient redundancy for recov‐
	      ering from simple read failures.	Disk group log copies

	      A disk contains 0, 1, or 2 disk group log copies. The number  of
	      log  copies  is  set  to the same as the number of configuration
	      copies for the disk (as explained in  the	 Configuration	copies
	      section above).

	      These  logs  are	written	 by  the  kernel when certain types of
	      actions  are  performed:	transaction  commits,  plex   detaches
	      resulting	 from I/O failures, total dirty region log (DRL) fail‐
	      ures, the first write to a volume, and  volume  close.  After  a
	      crash or a clean reboot, this log information is used to recover
	      the state of a disk group just prior to the crash or reboot.

	      Each disk group requires at least	 one  usable  disk  group  log
	      copy.  As with configuration copies, it is preferable to have at
	      least four log copies, allocated between at least two disks.  By
	      default,	the  same  disks  that store one or more configuration
	      copies also store the same number of log copies.

       For a single disk, the disk header and the table of contents blocks are
       critical	 data structures. At least one copy of the disk header, and at
       least one copy of each table of contents block, must  be	 readable  and
       usable,	or else the disk itself is unusable and will have to be reini‐
       tialized.

       Within disk groups, disk group configuration and log copies are	criti‐
       cal  data  structures. At least one complete configuration copy and log
       copy must be readable and usable, or the disk  group  is	 unusable  and
       will have to be reinitialized from scratch.

       All  disk  group	 association  information is stored in the disk header
       within private regions. This information consists of a disk group name,
       disk group unique ID, and a host ID. When the system boots, the Logical
       Storage Manager scans for disks that are stamped with the system's host
       ID. Each represented disk group is imported automatically. Disks with a
       non-matching host ID are not imported automatically, and cannot be used
       until you clear the host ID with the clearimport operation.

   Disk Types
       On Tru64 UNIX systems, three disk types are provided with the base Log‐
       ical Storage Manager: nopriv, simple, and sliced. The default is simple
       for  a  disk access name that specifies a partition (dsknp), and sliced
       for a disk access name that specifies the entire disk (dskn).

       The simplest disk type is nopriv, which defines a disk that has no pri‐
       vate  region,  and that consists only of space for allocating subdisks.
       Configuration and log copies cannot be stored on nopriv disks, so  they
       are  not self-identifying, and the Logical Storage Manager cannot track
       their movement on a SCSI chain or between controllers.

       The nopriv disk type is mainly used for encapsulation of existing data,
       or  for	defining special devices that you wish to use with the Logical
       Storage Manager, but that cannot store private  regions	(for  example,
       RAM disks).

       Initializing  a	nopriv	device with voldisk init creates a disk access
       record in the rootdg configuration, but does not write to the disk. The
       disk  ID	 for nopriv devices is stored in the disk access record in the
       rootdg configuration.

					Note

       Do not use the type=nopriv attribute to initialize a new disk  with  no
       configuration database. Instead, initialize a sliced or simple disk and
       use the nconfig=0 attribute setting.

       A simple disk has both a public and a private region, which are	stored
       on  a  single disk partition, with the public region following the pri‐
       vate region.

       A sliced disk has both a public and a private region, which are	stored
       on different disk partitions.

       The  disk label fstype tags for the various LSM disk types are: LSMpubl
       for the public region of a sliced disk LSMpriv for the  private	region
       of  a sliced disk LSMsimp for a simple disk (public and private regions
       are contained within the same partition) LSMnoprv  for  a  nopriv  disk
       (maps to an encapsulated disk or disk partition)

   Autoconfigured Disks
       On  Tru64  UNIX	systems, the Logical Storage Manager can get a list of
       known disk device addresses from the operating system. Any disks marked
       for  use	 by  LSM  are  automatically  configured into LSM when vold is
       started. Disks that are not configured  for  LSM	 use  appear  as  type
       sliced, with a status of UNKNOWN.

       If  LSM disks are not associated with a disk group, you can remove them
       from LSM use, if necessary, using voldisk rm. The  next	invocation  of
       voldisk list displays those devices as UNKNOWN, the same as if they had
       never been in use by LSM. If you reinitialize a disk for LSM  use,  the
       next  invocation	 of voldisk list reflects its changed status as an LSM
       disk. Disks are listed as either in use by  LSM	or  unknown,  but  not
       both.

       You  can	 disable  and  reenable LSM disks using the offline and online
       operations. However, the	 offline  state	 is  not  stored  persistently
       unless  there  is  an explicit device record in the configuration data‐
       base. If you need to persistently offline  a  device  at	 a  particular
       address, you must convert the address to use an explicit device record.
       To do this, remove the autoconfigured device (with voldisk rm), and use
       voldisk define to create an explicitly-configured device.

KEYWORDS AND ATTRIBUTES
       The  behavior of the voldisk utility depends upon the keyword specified
       as the first operand. Any attribute operands  override  default	values
       assigned for various disk attributes.

       Supported  keywords  and	 attributes are: Initializes regions of a disk
       for use by the Logical Storage Manager. This involves installing a disk
       header  and  writing an empty configuration on the disk. The accessname
       operand identifies the disk.

	      Normally, this command fails if the  disk	 already  contains  an
	      apparently  valid	 disk header. The -f option overrides this and
	      forces initialization of the disk. You cannot initialize a  disk
	      that is a member of an imported disk group.

	      The  voldisk init	 operation  creates a disk access record for a
	      disk (if one does not already exist),  and  sets	its  state  to
	      online.  If  the	root  configuration is disabled when a disk is
	      initialized, the disk header is initialized, but the disk is not
	      added  to	 the permanent list of known disks until the root con‐
	      figuration is enabled.

	      You can apply the following disk attributes with	voldisk	 init:
	      Specifies	 the  disk  device access type, which is a system-spe‐
	      cific name identifying a class of strategies for accessing disks
	      and for managing private and public regions. For Tru64 UNIX, the
	      valid disk_type names are: nopriv, simple, and sliced.  See  the
	      Disk  Types section for details.	Specifies that the device will
	      be left in the offline state, initially. This is	used  only  if
	      this  operation  is  defining a new disk access record.  For the
	      nopriv device type, this attribute specifies the	usable	length
	      of  the device, in 512-byte blocks. This is required if there is
	      no system-defined procedure for  determining  the	 disk  length;
	      otherwise, a suitable default is computed.

	      For  the	simple or sliced device type, this attribute specifies
	      the length of the public region, in 512-byte blocks. If this  is
	      not  specified, the length of the public region is computed from
	      available disk label information.	 If  no	 such  information  is
	      available, a public region length must be specified. The default
	      public region length is adjusted	to  account  for  the  private
	      region,  or  for any specified public or private region offsets.
	      Specifies the offset in blocks from the beginning of the	parti‐
	      tion containing the public region to the beginning of the public
	      region. Use this attribute if it is necessary to skip over  some
	      region  reserved	by  the operating system.  This attribute does
	      not apply to nopriv disks. For simple disks, use the  privoffset
	      attribute.

	      This  attribute defaults to 0. For sliced disks, an offset of 16
	      blocks or greater is a reasonable value. If the disk is a	 hard‐
	      ware  stripe  set,  you  can  use a different offset to maintain
	      stripe alignment.	 If this attribute is specified, the  disk  is
	      considered to have volatile contents (that is, the disk contents
	      are not expected to remain consistent across a  system  reboot).
	      Subdisks and plexes defined on disks with the volatile attribute
	      will inherit that attribute. The volume start  operation	inter‐
	      prets  volatile plexes as requiring a complete resynchronization
	      from other plexes in the same volume.

	      This attribute applies only to the nopriv device type.   Defines
	      the  partition to use for the public partition. The value of num
	      can be 0-7 (corresponding to  partitions	a-h).  This  attribute
	      applies  only  to the sliced device type.	 Defines the partition
	      to use for the private partition. The value of num  can  be  0-7
	      (corresponding  to  partitions a-h). This attribute applies only
	      to the sliced device type.

	      You can apply the following attributes with  voldisk  init  only
	      for  the	simple or sliced device types: Specifies the offset in
	      blocks from the beginning of the partition containing  the  pri‐
	      vate  region to the beginning of the private region. The default
	      is 0.

	      For a simple disk that occupies a partition that begins at block
	      0 (for example, when you initialize the disk specifying the a or
	      c partition), you should set the privoffset to 16 blocks. For  a
	      simple  disk  that  occupies  a partition that does not begin at
	      block 0 (for example, when you initialize	 the  disk  specifying
	      the b or d partition), the default of 0 is appropriate.

	      By default, the private region of a sliced disk is at the end of
	      the disk (the h partition) and needs no offset.	Therefore  the
	      privoffset default of 0 is appropriate.  Specifies the length of
	      the private region in blocks. If	this  is  not  specified,  the
	      default  of 4096 blocks is used. For a sliced disk, if no parti‐
	      tion information is available, a private region length  must  be
	      specified	 in  this command.  Specifies the number of configura‐
	      tion copies to store on the disk. The  number  of	 configuration
	      copies  will  be	the  same  as  the number of log regions.  The
	      default is 1, but you can set the attribute to 0 to specify that
	      no configuration copies be stored on the disk. A setting of 1 is
	      reasonable for disk groups that contain  three  or  more	disks.
	      This  allows  either  more  configuration	 records  or a smaller
	      reserved private region.	Specifies the size in  blocks  of  the
	      reserved	space for each copy of the configuration stored on the
	      disk. The default size is based on the size of the private  area
	      and  the	number	of  configuration copies requested, along with
	      some free space for uses other than  the	configuration  copies.
	      Specifies	 the  size in blocks of the reserved space in the pri‐
	      vate region for each log region. This size limits the number  of
	      kernel-initiated	detach	operations  that can be logged against
	      the disk group. The default is about 15% of the size of the con‐
	      figuration  copies.  It is advised that the log sizes be kept as
	      15% of the configuration	copy  size.   Defines  a  disk	access
	      record  without  initializing the disk. The Logical Storage Man‐
	      ager cannot scan a disk unless a disk access record  is  defined
	      for  the disk. Thus, to see what is on a new disk or to move one
	      or more disks that comprise a valid disk group from  one	system
	      to  another, you must first use voldisk define to make the disks
	      accessible. Then you can use voldisk list to see what is on  the
	      disks,  or  voldg import to import a disk group that is on those
	      disks.

	      Normally, a define operation fails if the specified disk	device
	      is  invalid (for example, if the disk is currently nonexistent).
	      The -f option forces the definition of an	 unusable  disk.  This
	      can  be  useful  in situations such as preparing the disk device
	      for use after a reboot. For example, if you intend to add a  new
	      controller  and  move some existing disks to the new controller,
	      you may need to define  the  new	disk  device  addresses,  even
	      though  they will not be usable until you shutdown and reconfig‐
	      ure your disks.

	      You can  define  the  following  disk  attributes	 with  voldisk
	      define: See the init keyword description for details.  Specifies
	      that the disk be created in the offline  state.	See  the  init
	      keyword  description for details.	 See the init keyword descrip‐
	      tion for details.	 See the init keyword description for details.
	      Sets  the	 disk  ID  to  the  newdiskid value in the disk access
	      record for the nopriv disk.  See the  init  keyword  description
	      for details.  See the init keyword description for details.  See
	      the init keyword description for	details.   Declares  the  disk
	      devices  named  by the accessname arguments to be in the offline
	      state. This disables checking of the  disk  when	searching  for
	      particular  disk	IDs,  or  for the set of disks in a particular
	      disk group.  You cannot place disks offline if they are  members
	      of an imported disk group.

	      A	 disk  should  be  placed offline if the disk is not currently
	      accessible, and if accessing the	disk  could  have  a  negative
	      impact on the system. For example, disk drivers on a few operat‐
	      ing systems can cause system panics or hangs if  an  attempt  is
	      made to access disks that are not accessible. In other operating
	      systems, attempts to access inaccessible drives may take several
	      seconds  or minutes before returning a failure.  Clears the off‐
	      line state for a disk device. This  reenables  checking  of  the
	      disk  when  searching  for  disk	IDs,  or for members of a disk
	      group. Use this attribute for disks  that	 are  already  in  the
	      online  state,  provided	that  they  are	 not  in imported disk
	      groups. All internal information for a disk that is  already  in
	      the online state is regenerated from the disk's private region.

	      The -a places on line all online disks that are not currently in
	      an imported disk group. Use this option to force the volume man‐
	      ager  to	rescan	all  disk headers, or to adapt to changes in a
	      disk's partitioning.  Removes the specified disk access records,
	      by  disk	access	name.	Lists detailed disk information on the
	      specified disks.

	      If no disk  arguments  are  specified,  a	 one-line  summary  is
	      printed for all disk access records known to the system.

	      If  disk arguments are specified, a full description of the con‐
	      tents of the disk header and of the table of contents is printed
	      for each named disk.

	      If  no  disk arguments are specified, but a disk group is speci‐
	      fied with -g, voldisk lists only those disks  belonging  to  the
	      specified disk group.

	      If  the -s option is specified, information from the disk header
	      is listed, including the disk ID, the host ID (if the disk is or
	      was imported), and the disk group ID and disk group name (if the
	      disk is a member of a disk group). With -s, the output format is
	      the same whether or not accessname arguments are specified.

	      If  the  -q option is specified, no header is printed describing
	      output fields. This option has no effect with the	 long  formats
	      generated	 with  -s  or  with  accessname arguments.  Clears the
	      host-specific import information stored on the indicated	disks,
	      and  in  the  configurations stored on those disks. This command
	      may be necessary in cases where import information stored for  a
	      disk  group  becomes unusable, due to host failures, or due to a
	      disk group being moved from one machine to another.

	      This operation does not apply to disks that are in imported disk
	      groups.	Validates  the usability of the given disks. A disk is
	      considered usable if the Logical Storage Manager can  write  and
	      read  back  at  least one of the disk headers that are stored on
	      the disk. If a disk in a disk group is found to be unusable,  it
	      is  detached  from its disk group and all subdisks stored on the
	      disk become invalid until the physical disk is replaced  or  the
	      disk media record is reassigned to a different physical disk.

					    Note

	      Since  a	nopriv	disk does not contain a disk header, the check
	      keyword might incorrectly report a failed nopriv	disk  as  okay
	      and  usable.  Changes some attributes for a disk. The attributes
	      are either simple names (used to turn an attribute on  or	 off),
	      or  can be of the form attrname=value, to indicate a value for a
	      particular attribute.

	      The set functionality is not currently implemented  for  any  of
	      the  existing disk types.	 Used with nconfig=count to change the
	      number of configuration copies  and  log	copies	for  the  disk
	      device  specified	 by the accessname argument. See the init key‐
	      word description for details on the nconfig attribute.

	      The size of the private region is fixed. If there are two copies
	      of the configuration database on a disk, each is limited to half
	      the space in the private region. By  decreasing  the  number  of
	      configuration  copies and log copies on a disk, the space avail‐
	      able for the remaining configuration database on that disk  will
	      be increased.

	      Refer to the Logical Storage Manager manual for more information
	      about when to use this option.

SEE ALSO
       volintro(8), vold(8), voldg(8), volume(8)

								    voldisk(8)
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