Document revision date: 30 March 2001

## OpenVMS DCL Dictionary

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If you do not specify a logical name for a magnetic tape drive, the MOUNT command assigns only one logical name, TAPE$volume-label, to the first magnetic tape device in the list. No default logical volume-set name is assigned in this case.

The MOUNT command places the name in the process logical name table, unless you specify /GROUP or /SYSTEM. In the latter cases, it places the logical names in the group or system logical name table.

If you specify the /CLUSTER qualifier, the logical name is established on each node in the cluster.

Note Avoid assigning a logical name that matches the file name of an executable image in SYS$SYSTEM. Such an assignment prohibits you from invoking that image.

Do not use the logical name assigned to a volume as a distributed file system (DFS) access point. If you attempt to add a DFS access point using the same name as the logical name, DFS fails as in the following example:

    $ SHOW LOG DISK$*
    (LNM$SYSTEM_TABLE)
       "DISK$TIVOLI_SYS" = "TIVOLI$DUA0:"
    $ MCR DFS$CONTROL
    DFS> ADD ACCESS DISK$TIVOLI_SYS TIVOLI$DUA0:[000000]
    %DNS-W-NONSNAME, Unknown namespace name specified

If the logical name of a volume is in a process-private table, then the name is not deleted when the volume is dismounted.

### Description

> The Mount command (MOUNT) is used to make a disk or magnetic tape available for processing. MOUNT allows you to ensure that the device has not been allocated to another user, that a volume is physically loaded on the device specified, and that the label on the volume matches the label specified. For magnetic tape volumes, MOUNT also checks the volume accessibility field of the VOL1 label.

> Normally, MOUNT allocates the device to the user who enters the command. However, mounting volumes with the /SHARE, /GROUP, or /SYSTEM qualifier deallocates the device, because the purpose of these qualifiers is to make the volume shareable.

> Note To mount a volume on a device, you must have read (R) or control (C) access to that device.

> Any subprocess in the process tree can mount or dismount a volume for the job. When a subprocess mounts a volume (for the job) as private, the master process of the job becomes the owner of this device. This provision is necessary because the subprocess may be deleted and the volume should remain privately mounted for this job. However, when a subprocess explicitly allocates a device and then mounts a private volume on this device, the subprocess retains device ownership. In this situation, only subprocesses with SHARE privilege have access to the device.

> Upon successful completion of the operation, MOUNT notifies you with a message sent to SYS$OUTPUT. If the operation fails for any reason, MOUNT notifies you with an error message.

> Certain file utilities such as MOUNT allocate virtual memory to hold copies of the index file and storage bitmaps. Beginning with larger bitmaps in OpenVMS Version 7.2, the virtual memory requirements of these utilities increase correspondingly. To use MOUNT on volumes with large bitmaps, you might need to increase your page file quota. On OpenVMS VAX systems, you might also need to increase the system parameter VIRTUALPAGECNT. The virtual memory size is shown as VAX pages (or Alpha 512-byte pagelets) per block of bitmap. Note that the size of the index file bitmap in blocks is the maximum number of files divided by 4096. The virtual memory requirements for MOUNT is equal to the sum of the sizes of all index file bitmaps and storage bitmaps on the volume set. This requirement applies to MOUNT only if you rebuild a volume.

> If you have a disk volume that you do not want the file system to cache, such as a database volume, use the /NOCACHE qualifier. This disables caching for the volume:

> - It stops the following metadata caches from caching any metadata for the volume on the local node:

>   > The Extent Cache
>   > The File Identifier Cache
>   > The Quota Cache

> - It stops the local Extended File Cache or Virtual I/O Cache from caching any files in the volume.

> MOUNT Usage Summary

> The Mount command (MOUNT) makes a disk or magnetic tape volume available for processing.

> To invoke MOUNT, enter the DCL command MOUNT, followed by the device name, volume label, and logical name. You must include a device name and a volume label (unless you specify /OVERRIDE=IDENTIFICATION or use the /FOREIGN or /NOLABEL qualifier); the logical name is optional.

> MOUNT returns you to the DCL level after it either successfully completes the operation or fails, generating an error message. If you press Ctrl/Y or Ctrl/C, MOUNT aborts the operation and returns you to the DCL prompt.

> You can direct output from MOUNT operations with the /COMMENT and /MESSAGE qualifiers. When the mount operation requires operator assistance, use /COMMENT to specify additional information to be included with the operator request. The /COMMENT text string is sent to the operator log file and to SYS$OUTPUT. The string must contain no more than 78 characters.

> Use the /MESSAGE qualifier (this is the default) to send mount request messages to your current SYS$OUTPUT device. If you specify /NOMESSAGE during an operator-assisted mount, messages are not sent to SYS$OUTPUT; the operator sees them, however, if an operator terminal is enabled to receive messages.

> Many MOUNT qualifiers require special privileges. Some qualifiers require different privileges according to which qualifier keyword you specify. See the individual qualifiers for details. The following table lists MOUNT qualifiers that require special privileges:

> Qualifier | Keywords | Required Privilege
> --- | --- | ---
> /ACCESSED |  | OPER
> /CACHE= | [NO]EXTENT[=n] | OPER
> | [NO]FILE_ID[=n] | OPER
> | [NO]QUOTA[=n] | OPER
> /FOREIGN |  | VOLPRO 1
> /GROUP |  | GRPNAM
> /MULTI_VOLUME |  | VOLPRO
> /OVERRIDE= | ACCESSIBILITY | VOLPRO 1
> | EXPIRATION | VOLPRO 1
> | LOCK | VOLPRO 1
> | SHADOW | VOLPRO 1
> /OWNER_UIC= | uic | VOLPRO 1
> /PROCESSOR= | UNIQUE | OPER
> | SAME:device | OPER
> | file-spec | OPER and CMKRNL
> /PROTECTION= | code | VOLPRO 1
> /QUOTA |  | VOLPRO 1
> /SYSTEM |  | SYSNAM
> /WINDOWS= | n | OPER

1Or your UIC must match the volume UIC.

### Qualifiers

> #### /ACCESSED=n

> Specifies, for ODS-1 disk volumes, the approximate number of directories that will be in use concurrently on the volume. (The /ACCESSED qualifier is meaningless for ODS-2 volumes.)

> Specify a value from 0 to 255 to override the default that was specified when the volume was initialized.

> You need the user privilege OPER to use /ACCESSED.

> Example

> The following command requests the volume labeled WORK to be mounted on DKA1, specifying 150 as the number of active directories on the volume:

>     $ MOUNT/ACCESSED=150 DKA1 WORK

> #### /ASSIST (default)

> #### /NOASSIST

> Directs the mount operation to allow operator or user intervention if the mount request fails.

> When you specify the /ASSIST qualifier, MOUNT notifies the user and certain classes of operator if a failure occurs during the mount operation. If a failure occurs, the operator or user can either abort the operation or correct the error condition to allow the operation to continue.

> The operator-assist messages are sent to all operator terminals that are enabled to receive messages; magnetic tape mount requests go to TAPE and DEVICE operators, and disk mount requests go to DISK and DEVICE operators. Thus, if you need operator assistance while mounting a disk device, a message is sent to DISK operators. See the description of the REPLY command for more information about enabling and disabling operator terminals.

> Any operator reply to a mount request is written to SYS$OUTPUT to be displayed on the user's terminal or written in a batch job log.

> If no operator terminal is enabled to receive and respond to a mount assist request, a message is displayed informing the user of the situation. If a volume is placed in the requested drive, no additional operator response is necessary. If the mount request originates from a batch job and no operator terminal is enabled to receive messages, the mount is aborted. Refer to the OpenVMS System Messages: Companion Guide for Help Message Users for a description of the error messages and their suggested user actions.

> The default is /ASSIST and can be overridden by /NOASSIST.

> Example

> The following command mounts an HSG80 Fibre Channel disk volume labeled DOC and assigns the logical name WORK. The /NOASSIST qualifier signals MOUNT that no operator intervention is necessary.

>     $ MOUNT/NOASSIST $1$DGA0: DOC WORK
>     %MOUNT-I-MOUNTED, DOC         mounted on _$1$DGA0: (NODE)

> #### /AUTOMATIC (default)

> #### /NOAUTOMATIC

> Determines whether MOUNT enables or disables automatic volume switching and labeling for magnetic tape or ISO 9660 CD-ROM.

> Magnetic Tape

> If you have multiple magnetic tape drives allocated to a volume set, the magnetic tape ancillary control process (MTACP) performs the volume switch by sequentially selecting the next available drive allocated to the volume set. The MTACP expects the next reel of the volume set to be loaded on that drive.

> If the MTACP is writing to the volume set, it creates a label and initializes the magnetic tape with that label and the protections established for the first magnetic tape of the volume set. If it is reading from the volume set, the MTACP generates the label and attempts to mount the next magnetic tape with that label. If the drive has the wrong magnetic tape (or no magnetic tape) loaded, the MTACP sends a message to the operator's console to prompt for the correct magnetic tape.

> The label generated by the MTACP fills the 6-character volume identifier field. The first four characters of the field contain the first four characters of the label specified in the MOUNT command, padded with underscores when the label is not at least four characters. The fifth and sixth characters contain the relative volume number for this reel in the volume set.

> If you specify /NOAUTOMATIC, the MTACP requires operator intervention to switch to the next drive during end-of-tape processing, and requires that the operator specify a label for each new reel added to a volume set.

> ISO 9660 CD-ROM

> Under ISO 9660, not all volume-set members must be mounted to perform I/O operations against that volume set. By default, if I/O operations attempt to access an unmounted volume-set member, an operator message is sent to all DISK CLASS operators for system-mounted volume sets, or the owning process for privately mounted volume sets. The message specifies the volume-set member to mount to complete the I/O operation requested. If /NOAUTOMATIC is specified, then an I/O operation to a nonmounted volume set member completes with an error message SS$_DEVNOTMOUNT.

> Example

> The following command instructs MOUNT not to generate its own label for the second volume, but to use the ones supplied with the MOUNT command instead. If the second volume is not already labeled, then the operator must use REPLY/INIT and supply the second label.

>     $ MOUNT/NOAUTOMATIC MTA0: ABCD,EFGH

> #### /BIND=volume-set-name

> Creates a volume set of one or more disk volumes or adds one or more volumes to an existing volume set.

> The parameter, volume-set-name, specifies a 1- to 12-alphanumeric-character name identifying the volume set.

> An ISO 9660 volume-set name can be from 1 to 128 characters in length.

> OpenVMS requires volume-set names to be unique in the first 12 characters. In addition, if the first 12 characters of volume-set name are the same as the first 12 characters of any volume label, a lock manager deadlock will occur. To avoid this problem, you must override either the volume label (by using the /OVERRIDE qualifier) or the volume-set name (by using the /BIND qualifier).

> You must specify the /BIND qualifier when you first create the volume set or each time you add a volume to the set. To dismount an individual volume of the volume set, you must use the DISMOUNT qualifier /UNIT; otherwise, dismounting an individual volume dismounts the entire volume set.

> When you create a volume set, the volumes specified in the volume-label list are assigned relative volume numbers based on their positions in the label list. The first volume specified becomes the root volume of the set.

> When you add a volume or volumes to a volume set, the first volume label specified must be that of the root volume, or the root volume must already be on line.

> Note that if you attempt to create a volume set from two or more volumes that already contain files and data, the file system does not issue an error message when you issue the MOUNT/BIND command. However, the volumes are unusable as a volume set because the directory structures are not properly bound.

> If you mount an ISO 9660 volume using the /SYSTEM or /CLUSTER qualifier, and the volume label is not unique within the first 12 characters, you must supply an alternate 12-character volume label using the qualifier /BIND=volume-set-name. If you choose this option, then Mount verification is disabled for the device.

> Note Once a volume is bound into a volume set, it cannot easily be unbound. To unbind a bound volume set (BVS): Do an image backup of the BVS. Initialize all volumes of the BVS. Do an image restore to a single volume with the /NOINITIALIZE qualifier, or do a nonimage restore to a single volume.

> Examples

> The following command creates a volume set named LIBRARY. This volume set consists of the volumes labeled BOOK1, BOOK2, and BOOK3, which are mounted physically on devices DMA0, DMA1, and DMA2, respectively.

>     $ MOUNT/BIND=LIBRARY  DMA0:,DMA1:,DMA2:  BOOK1,BOOK2,BOOK3

> The following command creates a volume set with the logical name TEST3. The volume set TEST3 is shadowed, and each element of the volume set (TEST3011 and TEST3012) is itself a shadowset.

>     $ MOUNT/BIND=TEST3 DSA3011/SHADOW=($1$DUA402:,$1$DUA403:),
>     DSA3012/SHADOW=($1$DUA404:,$1$DUA405:) TEST3011,TEST3012 TEST3

> #### /BLOCKSIZE=n

> Specifies the default block size for magnetic tape volumes.

> The parameter, n, specifies the default block size value for magnetic tape volumes. Valid values are in the range 20 to 65,532 for OpenVMS RMS operations, and 18 to 65,534 for non OpenVMS RMS operations. By default, records are written to magnetic tape volumes in 2048-byte blocks. For foreign or unlabeled magnetic tapes, the default is 512 bytes.

> You must specify /BLOCKSIZE in two situations:

> - When mounting magnetic tapes that do not have HDR2 labels. For these magnetic tapes, you must specify the block size. For example, you must specify /BLOCKSIZE=512 to mount an RT-11 magnetic tape.
> - When mounting magnetic tapes that contain blocks whose sizes exceed the default block size (2048 bytes). In this case, specify the size of the largest block for the block size.

> Example

> In the following example, the /BLOCKSIZE qualifier specifies a block size of 1000 bytes; the default for a magnetic tape mounted with the /FOREIGN qualifier is 512.

>     $ MOUNT/FOREIGN/BLOCKSIZE=1000 MTA1:

> #### /CACHE=(keyword[,...])

> #### /NOCACHE

> For disks, controls whether caching limits established at system generation time are disabled or overridden. With the TAPE_DATA option, enables write caching for the tape controller specified (if the tape controller supports write caching).

> The following table lists the keywords for this qualifier:

> Keyword | Description
> --- | ---
> EXTENT[=n] and NOEXTENT | Enable or disable extent caching. To enable extent caching, you must have the operator user privilege (OPER) and you must specify n, the number of entries in the extent cache. Note that NOEXTENT is equivalent to EXTENT=0; both disable extent caching.
> FILE_ID[=n] and NOFILE_ID | Enable or disable file identification caching. To enable file identification caching, you must have the operator user privilege (OPER) and you must specify n, the number of entries, as a value greater than 1. Note that NOFILE_ID is equivalent to FILE_ID=1; both disable file identification caching.
> LIMIT=n | Specifies the maximum amount of free space in the extent cache in one-thousandths of the currently available free space on the disk.
> QUOTA[=n] and NOQUOTA | Enable or disable quota caching. To enable quota caching, you must have the operator user privilege (OPER) and you must specify n, the number of entries in the quota cache. Normally n is set to the maximum number of active users expected for a disk with quotas enabled. Both NOQUOTA and QUOTA=0 disable quota file caching.
> TAPE_DATA | Enables write caching for a magnetic tape device if the tape controller supports write caching. The /CACHE qualifier is the default for mounting tape devices. You must specify TAPE_DATA to enable write caching. If the tape controller does not support write caching, the keyword is ignored. The write buffer stays enabled even after you dismount the magnetic tape. To disable the write buffer, mount a tape with the /NOCACHE qualifier. If a tape supports compaction, then the default is compaction, and caching is enabled. For tape storage devices that support compaction, the following command is valid:
>     $ MOUNT TAPE_DATA/FOREIGN/MEDIA=NOCOMPACTION/NOCACHE
> WRITETHROUGH | Disables the deferred write feature for file headers. By default, this feature is enabled, which improves the performance of applications, such as PATHWORKS, that use it. The deferred write feature is not available on Files-11 ODS-1 volumes.

> Used with the disk options, the /CACHE qualifier overrides one or more of the present disk caching limits established at system generation time. Used with the TAPE_DATA option, the /CACHE qualifier enables write caching for the tape controller specified.

> If you do not specify the /CACHE qualifier and it is not implied by the use of the qualifier /MEDIA_FORMAT=COMPACTION, caching is enabled by default.

> If you specify more than one option, separate them by commas and enclose the list in parentheses. The options [NO]EXTENT, [NO]FILE_ID, LIMIT, and [NO]QUOTA apply only to a disk device. The option TAPE_DATA applies only to a tape device.

> The /NOCACHE qualifier is effective only if compaction is not enabled. If compaction is enabled (with the /MEDIA_FORMAT=COMPACTION), caching is enabled by default.

> If you specify /NOCACHE for a disk device, all caching is disabled for this volume. Note that the /NOCACHE qualifier is equivalent to /CACHE=(NOEXTENT,NOFILE_ID,NOQUOTA,WRITETHROUGH).

> If you specify /NOCACHE for a magnetic tape device, the tape controller's write cache is disabled for this volume.

> Examples

> The following command mounts an HSG80 Fibre Channel disk device labeled FILES and assigns the logical name WORK. The /CACHE qualifier enables an extent cache of 60 entries, a file identification cache of 60 entries, and a quota cache of 20; it disables writeback caching of file headers.

>     $ MOUNT/CACHE=(EXTENT=60,FILE_ID=60,QUOTA=20,WRITETHROUGH) -
>     _$ $1$DGA0: FILES WORK
>     %MOUNT-I-MOUNTED, FILES         mounted on _$1$DGA0: (NODE)

> The following command mounts the volume TAPE on device MUA0 and instructs MOUNT to enable the tape controller's write cache for MUA0:

>     $ MOUNT/CACHE=TAPE_DATA MUA0:  TAPE
>     %MOUNT-I-MOUNTED, TAPE  mounted on _NODE$MUA0:

> #### /CLUSTER

> Specifies that after the volume is successfully mounted on the local node, or if it is already mounted /SYSTEM on the local node, it is to be mounted on every other node in the existing VMScluster (that is, the volume is mounted clusterwide).

> Only system or group volumes can be mounted clusterwide. If you specify the /CLUSTER qualifier with neither the /SYSTEM nor the /GROUP qualifier, the default is /SYSTEM. Note that you must use a cluster device-naming convention. Use either node$device-name or allocation-class$device-name as required by your configuration.

> You need the user privileges GRPNAM and SYSNAM, respectively, to mount group and system volumes clusterwide.

> If the system is not a member of an OpenVMS Cluster, the /CLUSTER qualifier has no effect.

> Example

> The following MOUNT/CLUSTER command mounts the volume SNOWWHITE on DOPEY$DMA1, then proceeds to mount the volume clusterwide. The SHOW DEVICE/FULL command displays information about the volume, including the other nodes on which it is mounted.

>     $ MOUNT/CLUSTER DOPEY$DMA1: SNOWWHITE DWARFDISK
>     %MOUNT-I-MOUNTED, SNOWWHITE         mounted on _DOPEY$DMA1:
>     $ SHOW DEVICE/FULL DWARFDISK:

>     Disk $2$DMA1: (DOPEY), device type RK07, is online, mounted,
>         file-oriented device, shareable, served to cluster via MSCP
>         Server, error logging is enabled.

>         Error count                0  Operations completed                159
>         Owner process             ""  Owner UIC                      [928,49]
>         Owner process ID    00000000  Dev Prot         S:RWED,O:RWED,G:RW,W:R
>         Reference count            1  Default buffer size                 512
>         Total blocks           53790  Sectors per track                    22
>         Total cylinders          815  Tracks per cylinder                   3
>         Allocation class           2

>         Volume label     "SNOWWHITE"  Relative volume number                0
>         Cluster size               3  Transaction count                     1
>         Free blocks            51720  Maximum files allowed              6723
>         Extend quantity            5  Mount count                           7
>         Mount status          System  Cache name      "_$255$DWARF1:XQPCACHE"
>         Extent cache size         64  Maximum blocks in extent cache     5172
>         File ID cache siz         64  Blocks currently in extent cache      0
>         Quota cache size          25  Maximum buffers in FCP cache        349

>       Volume status: ODS-2, subject to mount verification,
>          file high-water marking, write-through caching enabled.
>       Volume is also mounted on DOC, HAPPY, GRUMPY, SLEEPY, SNEEZY, BASHFUL.

> #### /COMMENT=string

> Specifies additional information to be included with the operator request when the mount operation requires operator assistance.

> The parameter, string, specifies a text string that is output to the operator log file and the current SYS$OUTPUT device. The string must contain no more than 78 characters.

> Examples

> The following command requests the operator to mount the disk volume TESTSYS on the device DYA1. Notice that the /COMMENT qualifier is used to inform the operator of the location of the volume. After the operator places the volume in DYA1, MOUNT retries the operation. After the operation completes, the operator request is canceled.

>     $ MOUNT DYA1:  TESTSYS/COMMENT="Volume in cabinet 6."
>     %MOUNT-I-OPRQST, Please mount volume TESTSYS in device _DYA1:
>     Volume in cabinet 6.
>     %MOUNT-I-MOUNTED TESTSYS    mounted on _DYA1:
>     %MOUNT-I-OPRQSTDON, operator request canceled - mount
>     completed successfully

> The following command is the same as in the previous example. However, in this example, because the requested device is in use, the operator aborts the mount.

>     $ MOUNT DYA1:  TESTSYS/COMMENT="Volume in cabinet 6."
>     %MOUNT-I-OPRQST, Please mount volume TESTSYS in device _DYA1:
>     Volume in cabinet 6.
>     %MOUNT-I-OPREPLY, This is a '/pending' response from the operator.
>     31-DEC-1990 10:27:38.15, request 2 pending by operator TTB6
>     %MOUNT-I-OPREPLY, This is a '/abort' response from the operator.
>     31-DEC-1990 10:29:59.34, request 2 aborted by operator TTB6
>     %MOUNT-F-OPRABORT, mount aborted by operator

> The following command requests the operator to mount the volume TESTSYS on the device DYA0. In this example, the operator notices that the requested device is in use and redirects the mount to device DYA1.

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