MDISK Directory Statement

Read syntax diagramSkip visual syntax diagram Mdisk vdev devtype Operands
Operands
Read syntax diagramSkip visual syntax diagramcylcylsENDvolid&SYSRESblkblksENDvolid&SYSRESDEVNOrdevV-DISKblksT-DISKcylsblksWmodemodesuffixPassword
Password
Read syntax diagramSkip visual syntax diagramprALLpwALLpmALL

Purpose

The MDISK statement defines minidisks (virtual disks) for virtual machines:
  • Permanent minidisks
  • Temporary minidisks
  • Virtual disks in storage

The DASDOPT and MINIOPT statements are extensions to the MDISK statement. The MDISK statement defaults to DEVCTL if no DASDOPT statement follows. For more information, see DASDOPT Directory Statement and MINIOPT Directory Statement. You can use one DASD to provide several minidisks or you can use one DASD to provide one minidisk (a full-pack minidisk).

Attention: CP and the directory program do not completely prevent you from defining minidisks that overlap. Overlap defeats the integrity of link access modes and RESERVE/RELEASE. If you define such overlap, you assume responsibility for data integrity.

How to Specify

MDISK statements are allowed within user, identity, and subconfiguration entries. If you specify the MDISK statement, it must follow any general statements that you specify in an entry. (For a list of general statements, see Table 1.)

In an SSI cluster, the scope of an MDISK definition can be global (accessible from all members of the cluster) or local (accessible from only one member of the cluster):
  • An MDISK definition for a permanent minidisk in a user or identity entry is global. The minidisk can be shared with users on any member of the cluster.
  • An MDISK definition for a permanent minidisk in a subconfiguration entry is local. The minidisk can be shared only with users on the member to which the subconfiguration entry applies.
  • An MDISK definition for a virtual disk in storage can be included only in a user or subconfiguration entry and is local. The minidisk can be shared only with users on the member where the minidisk is created.
  • An MDISK definition for a temporary minidisk is local. The minidisk is created on the member where the user logs on.

MDISK passwords for MDISKs in the subconfiguration entry are encrypted with the user ID from the IDENTITY statement.

DIRECTXA does not check for extra tokens that might be specified at the end of the MDISK statement. If you specify additional tokens, DIRECTXA ignores the extra tokens and system processing continues without regard for the extra tokens.

Operands

vdev
is the virtual device number of the minidisk.
devtype
is the device type of the minidisk.
  • For a permanent minidisk or temporary disk, this value is the device type of the real device on which the minidisk resides. Valid device types are:
    • 3380
    • 3390
    • 9336
    • FB-512

    FB-512 is a generic specification for FBA DASD and can be used in lieu of a specific FBA device type (9336). A 3390 in 3380 track-compatibility mode must be coded as a 3380.

  • For a virtual disk in storage, which is not mapped to a real DASD, this value is the device type of the device that is simulated in host storage. A virtual disk in storage simulates an FBA minidisk; therefore, the device type must be FB-512.
cyl
blk
is the starting cylinder (ECKD) or block number (FBA) on the real DASD you specify on the volid operand. Generally, ECKD user minidisks must begin with cylinder 1 or higher and FBA user minidisks must begin with block 32 or higher. If the SALIPL utility was used to previously install a copy of the Stand-Alone Program Loader (SAPL), then FBA DASD user minidisks must begin with block 208 or higher.
DEVNO
specifies a full-pack minidisk.
V-DISK
indicates that the minidisk is a virtual disk in storage. A virtual disk in storage is temporary but shareable. It is created when the first user links to it and destroyed when the last user detaches it or logs off.

The V-DISK operand is not allowed on an MDISK statement in an identity entry.

T-DISK
indicates that the minidisk is temporary. The minidisk is created from a preselected pool of temporary disk space when the virtual machine logs on. The minidisk is returned to the pool when the virtual machine logs off or the virtual device is detached. Temporary minidisks cannot have passwords and cannot be shared.
cyls
blks
is the number of cylinders (ECKD) or blocks (FBA) allocated to the minidisk. Table 1 shows the number of cylinders or blocks available in each format for each device type on which you can put minidisks.
END
specifies that the minidisk is defined with the remaining available cylinders or blocks. This is useful when a full-pack minidisk is defined. For more information, see usage note 4.
rdev
is the real device number.
volid
is the volume serial number of the real DASD volume on which the minidisk resides.
&SYSRES
indicates that the minidisk resides on whichever real DASD is the VM system residence volume. This volume is established when VM is IPLed but can change from one IPL to another.

Use the &SYSRES option of the DIRECTXA command to assign a value to represent the volume serial number of the system residence volume for minidisks that are defined by using the &SYSRES operand on the MDISK statement. The value that is used on the &SYSRES option of the DIRECTXA command is substituted for &SYSRES on the MDISK statement and used regardless of the actual system residence volume.

This value is used in responses from the VMUDQ LISTMDSK function. If the &SYSRES option is omitted on the DIRECTXA command, a value of +VMRES is used.

Note: If the SSI option is added to the DIRECTORY statement, the following are not allowed on the MDISK statement:
  • &SYSRES
  • +VMRES
  • volids that match the value that is supplied by the &SYSRES option of the DIRECTXA command.
mode
is the access mode for the minidisk. The first letter in the access mode is the primary access mode (read-only, write, or multiple-write); the second letter (optional) is the alternate access (read-only or write).

The access modes are:

R
Read-only access. Read access is established, unless another user holds a write or an exclusive mode (ER, EW) access to the disk.
RR
Read-only access. Read access is established, unless another user holds an exclusive mode (ER, EW) access.
W
Write access. Write access is established, unless another user holds access (any mode) to the disk. If you do not specify an access mode on the MDISK statement, the default is W.
WR
Write access. Write access is established unless another user holds access (any mode) to the disk. If write access is denied, read access is established unless another user holds an exclusive (ER, EW) mode access for the disk.
M
Multiple-write access. Write access is established unless another user holds a write, a stable (SR, SW, SM) or an exclusive (ER, EW) mode access to the disk.
MR
Multiple-write access. Write access is established unless another user has a write, stable (SR, SW, SM) or exclusive mode (ER, EW) access to the disk. If another user has write or stable (SR, SW, SM) access, read-only access is established. If an exclusive mode access exists, access is denied.
MW
Multiple-write access. Write access is established in all cases except when another user holds either a stable (SR, SW, SM) or an exclusive mode (ER, EW) access to the disk.
modesuffix
The optional mode suffix letters authorize virtual reserve/release and the use of the stable and exclusive (data integrity) access modes of the CP LINK command and DIAGNOSE code X'E4'. The specification here on the MDISK statement allows the user to enter a LINK command with the specified type of access mode, stable, or exclusive. For more information, see LINK.

The suffix letters can be combined as follows (note that CP requires they be specified in this order):

  1. V or null, plus
  2. S, E, or null (S and E are mutually exclusive), plus
  3. D or null

Therefore, the only valid combinations are: V, S, E, D, VS, VE, VD, VSD, VED, SD, or ED. This suffix is in turn concatenated with the mode, with no intervening blanks. For example, RV, RRS, WVE, and MVSD are all valid.

V
Tells CP to use its virtual reserve/release support in the I/O operations for the minidisk. For example, MWV means the minidisk functions with write linkage by using CP's virtual reserve/release.
S
Authorizes the virtual machine in whose virtual machine definition this statement appears the ability to use the LINK command stable access modes (SR, SW, SM) against the specified user's minidisk. For more information, see LINK.
E
Authorizes the virtual machine in whose virtual machine definition this statement appears the ability to use the LINK command exclusive and stable access modes (ER, EW, SR, SW, SM) against the specified user's minidisk. For more information, see LINK.
D
Tells CP that the device must not be defined when the virtual machine initially logs on or is auto logged. The definition is deferred until an explicit LINK command is issued for that device.
pr
ALL
is the password that allows sharing the minidisk (by using the CP LINK command) in read mode. The variable pr is a 1- to 8-character string. If you specify ALL, a user can link in read mode to this minidisk without using a password.
pw
ALL
is the password that allows sharing the minidisk (by using the CP LINK command) in write mode. If you specify ALL, a user can link in write mode to this minidisk without using a password.
pm
ALL
is the password that allows sharing the minidisk (by using the CP LINK command) in multiple-write mode. The variable pm is a 1- to 8-character string. If you specify ALL, a user can link in multiple-write mode to this minidisk without using a password.
Table 1. Maximum Minidisk Sizes
Device Type and Model Maximum Size (Cylinders/Blocks) CMS/VSAM Size Limits
3390-1 (See note 1) 1113 cylinders 1113 cylinders
3390-2 (See note 1) 2226 cylinders 2226 cylinders
3390-3 (See note 1) 3339 cylinders 3339 cylinders
3390-9 (See note 2) 65520 cylinders 10017 cylinders (See notes 3,4,6)
3390-A 1182006 cylinders 65520 cylinders
9336-020 2147483640 blocks 381 GB (See notes 5,6)
FB-512 (virtual disk in storage) 4194296 blocks 4194296 blocks
Notes:
  1. These capacities apply to 3390 mode and 3380 track compatibility mode.
  3. Minidisks that are used with VSAM are limited to 64 KB (65,536) tracks (4369 3390 cylinders). This is a limitation of the VSE/VSAM licensed program. This limit applies whether the minidisk is used by a VSE guest or by CMS/VSAM.
  4. Value can be up to the maximum number of cylinders on the DASD (GCS is limited to 32,767 cylinders; CMS limits depend on the 3390-9 capacity model: 32,767 for a Mod 27 and 65,520 for a Mod 54.)
  5. z/VM supports a SCSI disk, which is emulated as a 9336-020, up to a capacity of 268,435,455 4096-byte pages (1 terabyte minus one page). However, directory, paging, and spooling allocations must reside within the first 16,777,215 pages (64 GB minus one page) of a CP-formatted disk.
  6. The CMS file system requires that file status and control information resides in the virtual address lower storage region, at an address that is less than 16 MB. Hence, the size of CMS minidisks has a practical limitation. As a minidisk increases in size, or more files reside on the disk, the amount of virtual storage that is required for CMS file system status and control increases. The current ECKD DASD limitation for CMS is 65520 cylinders for a 3390 disk on an IBM® TotalStorage DASD subsystem, or about 45 GB of data. The maximum supported size for FBA SCSI disks that are used by CMS or GCS is 381 GB. A practical limit for CMS minidisks is about 22 GB. If larger disks are defined, they must contain few files. Larger disks with more files might cause a problem for the CMS file system to obtain enough virtual storage in the lower storage region to format or access those disks. For more information, see CMS ACCESS.

Usage Notes

  1. You must format a temporary minidisk or virtual disk in storage before you use it. If you want to format the disk for CP use, use the Device Support Facility (ICKDSF) program; it is the recommended method of CP volume maintenance. For more information about ICKDSF procedures, see the Device Support Facilities User's Guide and Reference, GC35-0033. If you want to format the disk for CMS use, use the CMS FORMAT command. For more information, see CMS FORMAT. To format minidisk space for other operating systems, use the commands of the operating system that controls the minidisk.
  2. For security, temporary disk space that contains sensitive data can be reformatted before the disk is detached from the virtual machine. If the system is configured to clear all temporary disk space, this clearing is done by the system. You can determine whether temporary disk clearing is enabled by entering the QUERY TDISKCLR command. Temporary disk clearing removes any risk of security exposure.
  3. If for some reason two or more volumes have the same label, CP defines the minidisk on the volume that is attached to the system. (You cannot attach two volumes with the same label to the system at the same time.)
  4. To define a full-pack minidisk, you must specify that the minidisk is to contain all of a DASD's primary cylinders or blocks. Specify '0' to 'END' on the MDISK statement.
    Note:
    • A minidisk that begins with cylinder 1 or block 1 is not a full-pack minidisk.
    • Define by using the keyword 'END' so your MDISK statement is not dependent on the size and type of DASD.

    You can specify any of the DASD's alternate cylinders or blocks, but those cylinders or blocks, and all others, are accessible to anyone with a full-pack minidisk.

  5. Full-pack minidisks that overlap other minidisks are ignored during link access mode checking. However, you must not define any other type of overlap. CP checks overlap to ensure the integrity of link access modes. This is not a feature to exploit.
    If you do overlap other minidisks, you might experience the following consequences:
    • You cannot link to those minidisks and receive messages HCP104E, HCP105E, and HCP106E.
    • You can link only in read-only mode to those minidisks and receive messages HCP101E, HCP102E, and HCP103E.
  6. CP volumes are supported in either 3380 track compatibility mode or 3390 mode of operation on a volume basis except for the 3390 Model 9, which does not support 3380 track compatibility mode.
  7. Read Special home address and Write Special home address CCWs are only supported for dedicated and full-pack minidisks for guests with the OPTION statement value MAINTCCW or DEVMAINT.
  8. The use of the stable (SR, SW, and SM) and exclusive (ER and EW) link modes can be authorized in two different ways:
    • Globally, by using the OPTION statement values LNKSTABL and LNKEXCLU
    • Specifically, by using the mode suffix letter on the MDISK or LINK statements
  9. The DEVNO operand allows the user to define a full-pack minidisk by specifying the real device number of the minidisk. This operand must be used when you define full-pack minidisks where the guest controls the duplexing of the device.
  10. The DEVNO operand must be used when you define multiple minidisks with identical volume serial numbers.
  11. Refer to the appropriate storage control manuals for more dual copy information.
  12. For information on the use of the MDISK statement for the CMS shared file system, refer to z/VM: CMS File Pool Planning, Administration, and Operation .
  13. If an external security manager (ESM) is installed, you might not be authorized to use the MDISK statement for all minidisks and all access modes. The ESM might downgrade certain requests for write access to read access. For additional information, contact your security administrator.
  14. Virtual disks in storage and FBA temporary minidisks are created in 8-block pages. Therefore, the size of the virtual disk in storage or FBA temporary minidisk that is created might be rounded up to the nearest page.
  15. If you define a minidisk as virtual device number 192, the following special rules apply when you IPL CMS:
    • If 192 is an unformatted temporary minidisk or virtual disk in storage, CMS formats it and accessed it as file mode D.
    • If 192 is a CP-formatted temporary minidisk or virtual disk in storage, CMS reformats it for CMS use and accesses it as file mode D.
    • If 192 is a CMS-formatted temporary minidisk, virtual disk in storage, or permanent minidisk that is accessed as a file mode other than D, CMS reaccesses it as file mode D.
    • If 192 is an unformatted or CP-formatted permanent minidisk, CMS does not automatically format, reformat, access, or reaccess it.

    When CMS accesses a 192 minidisk as file mode D, any minidisk or SFS directory that is already accessed as D is released.

  16. If you change the definition of a permanent minidisk while users are linked to it, existing links are unchanged. However, any new links are made by using the new definition of the minidisk. Unpredictable results might occur.
  17. If you change the definition of a virtual disk in storage while users are linked to it, existing links are unchanged. Any new links are made to the existing virtual disk in storage. The existing virtual disk in storage is used until the last user detaches it or logs off, at which time the virtual disk in storage is destroyed. After that, any new links use the new definition of the virtual disk in storage.
  18. Some programs might not support the use of &SYSRES, and require the use of a synonym. The synonym is the value that is specified on the DIRECTXA command with the &SYSRES operand. If the &SYSRES option is omitted on the DIRECTXA command, a synonym of +VMRES is used. In other words, either &SYSRES or its synonym can be used to define a minidisk on the system residence volume.
  19. A minidisk, including a temporary disk, is not eligible for minidisk cache if it is defined with greater than 32767 cylinders. This restriction does not apply to FBA devices. The restriction applies only to ECKD devices.
  20. For more information about the V mode suffix restrictions when linking, see LINK.
  21. In an SSI cluster, if a virtual disk in storage is defined in a user entry, the minidisk can be created on any member of the cluster. The minidisk is created when the owner logs on or when the first user links to it. After creation, the minidisk can be shared only by other users on that member until the last user detaches it or logs off.
  22. If a temporary minidisk is defined in an identity entry, a separate temporary minidisk is created for each logon instance of the virtual machine.
  23. Minidisk cache is not supported for a minidisk that is defined on an extended address volume (EAV) DASD such as the 3390-0E. The restriction is because of the large number of cylinders that are supported by that device.
  24. The cyl operand of the MDISK statement and the cyls option of the TDISK operand allow values up to 1,182,006 cylinders.

Examples

  1. Define a minidisk that has the following features:
    • Has the virtual device number 191
    • Takes up five cylinders, from cylinder 100, of the 3390 DASD with volume serial MDDASD
    • Is accessible only in read-only mode
    • Cannot be linked to in any mode (no passwords are specified)
    Use the following MDISK statement in the virtual machine definition: 
      Mdisk 191 3390 100 5 mddasd rr
  2. Define a minidisk that has the following features:
    • Has the virtual device number 291
    • Takes up 10 cylinders, from cylinder 105, of the 3390 DASD with volume serial MDDASD
    • Is accessible only in read or write mode
    • Can be linked to by anyone in read mode (but no other mode)
    Use the following MDISK statement in the virtual machine definition: 
      Mdisk 291 3390 105 10 mddasd mr all
  3. Define a minidisk that has the following features:
    • Has the virtual device number 198
    • Takes up 6000 blocks, from block 12,000, of a supported FBA DASD with volume serial FBDASD
    • Is accessible only in multiple-write (MW) modes
    • Can be shared by using CP's virtual reserve/release
    • Has a read password of 12WE45
    Use the following MDISK statement in the virtual machine definition: 
      Mdisk 198 9336 12000 6000 fbdasd mwv 12we45
  4. Define a minidisk that has the following features:
    • Has the virtual device number 198
    • Takes up 6000 blocks, from block 12,000, of the 9336 DASD with volume serial FBDASD
    • Has the default access mode of Write when the virtual machine is logged on, but specifically authorizes the user to access it with a stable access mode by using the LINK command later.
    • Can be shared by using CP's virtual reserve/release
    • Has a read password of 12WE45
    Use the following MDISK statement in the virtual machine definition: 
      Mdisk 198 fb-512 12000 6000 fbdasd mvs 12we45
  5. To define five cylinders of temporary 3390 DASD space at virtual device number 391, use the following MDISK statement in the virtual machine definition: 
      Mdisk 391 3390 t-disk 5
  6. To define 4000 blocks of temporary FBA DASD space at virtual device 392, use the following MDISK statement in the virtual machine definition: 
      Mdisk 392 fb-512 t-disk 4000
  7. To define a 3380 DASD full-pack minidisk at virtual device number 199, use one of the following MDISK statements in the virtual machine definition: 
      Mdisk 199 3380 000 885 mddasd mr
  Mdisk 199 3380 000 end mddasd mr
  8. Define a pair of full-pack minidisks that are candidates for duplexing and have the following features:
    • Have virtual device numbers 198 and 199
    • Have real device numbers 200 and 201
    • Are accessible in read or write mode
    • Can be linked to by anyone in read mode
    Use the following MDISK statements in the virtual machine definition: 
      mdisk 198 3390 devno 200 mr all
  mdisk 199 3390 devno 201 mr all
  9. Define a minidisk that has the following features:
    • Has virtual device number 401
    • Consists of 8000 blocks
    • Is accessible in read or write mode
    • Can be shared by using CP's virtual reserve/release
    Use the following MDISK statement in the virtual machine definition: 
      mdisk 401 fb-512 v-disk 8000 mwv
  10. To define a minidisk that uses a synonym of VM-RES instead of &SYSRES, use the following MDISK statement: 
       MDISK 123 3390 0 END VM-RES RR
    And use the following command to place the directory online: 
    DIRECTXA USER DIRECT (&SYSRES VM-RES

Minidisk Restrictions

The following restrictions exist for minidisks:

  1. In the following cases, z/VM modifies the cylinder data in user storage at the completion of the channel program:
    • Read Home Address (with the skip bit off)
    • Read Record Zero (with the skip bit off)
    • Sense (with the skip bit off)
    • Read Track (with the skip bit off)
    • Read Device Characteristics.

    This is necessary because the addresses must be converted for minidisks. Therefore, the data buffer area cannot be dynamically modified during the I/O operation in these cases.

    Note: For the Read Record Zero case, the restriction does not apply to devices that do not provide alternate track recovery.
  2. On a minidisk, if a CCW string uses multitrack-search on I/O operations, subsequent operations to that disk must have preceding seeks or continue to use multitrack operations. Dedicated disks are not restricted.
  3. If the user's channel program for a count-key-data minidisk does not complete a seek operation, CP inserts a positioning seek operation into the user's channel program to prevent accidental accessing. Thus, certain channel programs might generate a condition code (CC) of 0 on an SIO instead of the expected CC of 1, which is reflected to a virtual machine. The final status is reflected to the virtual machine as an interruption. The final states for some channel programs that are initiated through an SIOF or SSCH might not indicate deferred CC 1.
  4. A DASD channel program might give results on dedicated DASD that differ from results on minidisks that have nonzero relocation factors if the following conditions are true:
    • The channel program includes multiple-track operations.
    • The channel program depends on a Search ID High or Search ID Equal or High to terminate the program.
    The record 0 count fields on these devices must contain the real cylinder number of the track on which they reside. Therefore, a Search ID High, for example, based on a low virtual cylinder number, might terminate prematurely if a real record 0 is encountered.

    Minidisks with nonzero relocation factors are not usable under OS and OS/VS systems. The restriction is because the locate catalog management function employs a Search ID Equal or High CCW to find the end of the VTOC.

  5. The IBCDASDI program cannot assign alternate tracks.
    Notes:
    1. Device-Support Facilities (ICKDSF) might assign alternate tracks
    2. Alternate track assignment is permitted for full-pack minidisks only.
  6. If the DASD channel programs include a Write Record Zero CCW or a Write Home Address CCW, the results depend on whether the device is dedicated or not dedicated.
    • For a dedicated DASD, a Write Record Zero or a Write Home Address CCW is allowed. However, the user must be aware that the track descriptor record might not be valid from one DASD to another.
    • For a DASD that is not dedicated, a Write Record Zero or a Write Home Address CCW is accepted only if the device is a full-pack minidisk. CP rejects the command if the device that issues a Write Record Zero or a Write Home Address CCW on a nondedicated DASD is not defined as a full-pack minidisk.
  7. During DASD I/O, the real Search ID uses the relocated search argument instead of the argument that was read dynamically if the following conditions are true:
    • The record field of a Search ID Argument is zero when a virtual SIO, SIOF, or SSCH is issued
    • The Search ID Argument is dynamically read by the channel program before the Search ID CCW is executed.
    This problem can be avoided if you do not set the record field of a Search ID Argument to binary zero in the following cases:
    • The search argument is read dynamically.
    • The search ID on record 0 is not intended.
  8. The following CCWs are restricted to virtual machines with MAINTCCW authority. You specify this authority by coding the MAINTCCW operand on the OPTION statement in the virtual machine definition.
    • Diagnostic Write Home Address
    • Diagnostic Read Home Address
    • Write Record Zero
    • Diagnostic Load
    • Diagnostic Sense/Reset Allegiance: CP treats the command as a reset allegiance CCW and accepts it if it is the first CCW in the channel program.
    • Diagnostic Write
    • Diagnostic Sense/Read
    • Diagnostic Control
  9. Diagnostic Read Home Address and Diagnostic Write Home Address commands are supported only for dedicated and full-pack 3380 and 3390 minidisks.

    All Diagnostic CCWs are restricted to users with the OPTION statement value MAINTCCW or DEVMAINT.

  10. Refer to OS/VS Device Support Facilities for procedures to format all supported DASDs for use in an OS/VS operating system that runs in a virtual machine.
  11. The 3390s that are used for CP volumes are supported in either 3380 track compatibility mode or 3390 mode of operation on a volume basis. The exception is the 3390 Model 9, which does not support 3380 track compatibility mode. The ability to change operating modes is restricted to guests with the OPTION statement value MAINTCCW or DEVMAINT. The use of ICKDSF is the recommended method to change modes.
  12. A user must not have an MDISK statement with the DEVNO operand and an MDISK statement with the volume serial number operand for the same volume.
  13. Access to cache control units is controlled by the settings of level of control in the DASDOPT directory statement. For more information, see DASDOPT Directory Statement.
  14. Minidisks that are defined on an FBA volume and are not page-aligned are not eligible for minidisk cache. Hence, those minidisks do not benefit from a performance improvement. Aligning minidisks on page boundaries is highly recommended. Minidisks and full-pack minidisk volumes that are not page-aligned might result in residual blocks that are not formatted and not used. Additional restrictions apply for SFS Filepool minidisks that are not page-aligned. For more information, see z/VM: CMS File Pool Planning, Administration, and Operation . If the starting block number is a multiple of eight and the number of blocks is a multiple of eight, then the minidisk is defined to be page-aligned.
    Note: Under the conditions outlined in this usage note, residual blocks on FBA devices that are ICKDSF formatted can still be defined and used as MDISK space.
  15. Minidisks that are defined on an FBA volume and are not page-aligned cannot be mapped to an address space by using minidisk mapping.