Document revision date: 15 July 2002

Use SHOW DEVICE in the following format to display information about shadow sets:

SHOW DEVICE [virtual-unit-name[:]]

The variable virtual-unit-name replaces device-name as the SHOW DEVICE command parameter for shadow sets. Use the virtual unit naming format DSAn:.

As with any SHOW DEVICE command, the colon is optional. Note also that you can specify a complete virtual unit name (or a portion of a virtual unit name) just as you can with device names. If you omit the virtual unit number, SHOW DEVICE lists all the shadow set virtual units that represent shadow set member disks of the type specified. If you truncate a device name (for example, if you specify D), SHOW DEVICE lists all the devices and all the virtual units that begin with the letters you entered (in this case, D).

When you specify the virtual unit number, SHOW DEVICE displays the names of the shadow set members it represents. If you use the /FULL qualifier, SHOW DEVICE displays full information about the shadow set and all the associated shadow set members.

Because individual shadow set members that are mounted for systemwide or clusterwide access are not allocated or mounted in the traditional sense, a SHOW DEVICE command with the /ALLOCATED or /MOUNTED qualifiers displays only virtual units.

4.9.2 Listing Shadow Set Members

Use the same format for the SHOW DEVICE command with shadow set members as you use with other physical devices. The command lists all shadow set members of the device name you specify.

Because shadow set members are not mounted in a traditional sense and they all have the same device characteristics, SHOW DEVICE displays most of the relevant data with the associated virtual unit. Listings of shadow set members include information about current membership status.

If a shadow set is undergoing a copy or a merge operation, the display resulting from the SHOW DEVICE command includes the percentage of the disk that has been copied or merged. The SHOW DEVICE information is available on all nodes that have the shadow set mounted.

The SHOW DEVICE display indicates the exact percentage of the disk that has been copied. The node that is managing the copy operation knows precisely how far the copy or merge operation has progressed, and periodically notifies the other nodes in the OpenVMS Cluster of the progress. Thus, the other nodes in the cluster know approximately the percentage copied. When you enter the SHOW DEVICE command from a node other than the one where the copy or merge operation is taking place, the number indicating the percentage copied in the SHOW DEVICE output lags (by a small percentage) the actual percentage copied.

Note that if a copy and a merge operation are occurring at the same time in the same shadow set, the number indicating the percentage merged remains static until the copy completes. Then the merge operation proceeds to completion.

4.9.3 SHOW DEVICE Examples for Shadow Set Information

The following examples of output from the SHOW DEVICE command illustrate the types of shadow set information you can obtain, such as shadow set membership and the status of each shadow set member during copy and merge operations. For examples of output for write bitmaps used with the minicopy operation, see Section 7.10.

Examples

$ SHOW DEVICE D
Device               Device        Error    Volume         Free  Trans Mnt
 Name                Status        Count     Label        Blocks Count Cnt
DSA0:                Mounted           0  SHADOWDISK        8694   151   1
DSA9999:             Mounted           0  APPARITION      292971     1   1
$4$DUA0:   (SYSTMX)  Online            0
$4$DUA8:   (HSJ001)  ShadowSetMember   0  (member of DSA0:)
$4$DUA10:  (SYSTMX)  ShadowSetMember   0  (member of DSA9999:)
$4$DUA11:  (SYSTMX)  ShadowSetMember   0  (member of DSA9999:)
$4$DUA12:  (SYSTMX)  ShadowSetMember   0  (member of DSA9999:)
$4$DUA89:  (HSJ002)  ShadowSetMember   0  (member of DSA0:)
      

By truncating the device name, you cause the SHOW DEVICE command to list all the devices and all the virtual units on the local node that begin with the letters you entered (in this case, D). This example shows that two virtual units, DSA0 and DSA9999, are active. Both shadow sets are in a steady state. The device status "ShadowSetMember" indicates that the shadow set is in a steady state---the shadow set members are consistent with each other.

$ SHOW DEVICE DSA8
Device               Device        Error    Volume         Free  Trans Mnt
 Name                Status        Count     Label        Blocks Count Cnt
DSA8:                Mounted           0  APPARITION      890937     1   1
$11$DUA8:   (SYSTMX)   ShadowSetMember   0  (member of DSA8:)
$11$DUA89:  (SYSTMY)   ShadowSetMember   0  (member of DSA8:)
      

This example shows the membership and status of the shadow set represented by the DSA8 virtual unit. The SHOW DEVICE display provides information not only about the virtual unit DSA8, but also about the physical devices $11$DUA8 and $11$DUA89 that are members of the shadow set. The device status "ShadowSetMember" indicates that the shadow set is in a steady state---the shadow set members are consistent with each other. The shadow set members are being served by OpenVMS Cluster nodes SYSTMX and SYSTMY.

$ SHOW DEVICE DSA
Device               Device        Error    Volume         Free  Trans Mnt
 Name                Status        Count     Label        Blocks Count Cnt
DSA7:                Mounted           0  PHANTOM          27060    35   7
DSA8:                Mounted           0  APPARITION      890937     4   6
 
      

You might specify DSA on the SHOW DEVICE command to request information about all the shadow sets on the local node. Entering a generic virtual unit name, such as DSA, as a parameter produces a display of all virtual units representing shadow sets mounted on the local system. This example shows that two shadow sets are mounted on the local node, represented by the virtual units DSA7 and DSA8.

$ SHOW DEVICE $11$DUA8:
Device               Device        Error    Volume         Free  Trans Mnt
 Name                Status        Count     Label        Blocks Count Cnt
DSA8:                Mounted           0  APPARITION      890937     1   1
$11$DUA8:   (HSJ001) ShadowSetMember   0  (member of DSA8:)
$11$DUA89:  (HSJ002) ShadowSetMember   0  (member of DSA8:)
      

Although the SHOW DEVICE command specifies the name of a single device, the resulting display includes information about the membership and status of the shadow set represented by the DSA8 virtual unit to which the $11$DUA8 device belongs. The device status "ShadowSetMember" indicates that the shadow set is in a steady state---the shadow set members are consistent with each other. The shadow set members are accessed through the node named HSJ001.

$ SHOW DEVICE $11$DUA8:
Device               Device        Error    Volume         Free  Trans Mnt
 Name                Status        Count     Label        Blocks Count Cnt
DSA8:                Mounted           0  APPARITION      890937     1   1
$11$DUA8:  (HSJ001)  ShadowSetMember   0  (member of DSA8:)
 
$11$DUA89: (HSJ002)  ShadowCopying     0  (copy trgt DSA8:  48% copied)
 
      

The output from this SHOW DEVICE command shows a shadow set that is in a transient state. The device status "ShadowCopying" indicates that the physical device $11$DUA89 is the target of a copy operation, and 48% of the disk has been copied. The device $11$DUA8 is the source member for the copy operation.

$ SHOW DEVICE DSA8
Device               Device        Error    Volume         Free  Trans Mnt
 Name                Status        Count     Label        Blocks Count Cnt
DSA8:                Mounted           0  APPARITION      890937     1  12
 
$11$DUA8:  (HSJ001)  ShadowCopying     0  (copy trgt DSA8: 5% copied)
$11$DUA89: (HSJ002)  ShadowMergeMbr    0  (merging DSA8:   0% merged)
 
      

This example shows how the SHOW DEVICE command displays a shadow set during a copy operation after a node in an OpenVMS Cluster system fails. In this example, the shadow set members are located on different nodes in the cluster, and one node on which the shadow set is mounted fails. At the time of the failure, the shadow set was in a transient state, with the $11$DUA8 device undergoing a copy operation. The SHOW DEVICE command shows the state of the shadow set during the copy operation, before the merge operation occurs.

At the same time the $11$DUA89 shadow set member is acting as the source member for the copy operation, $11$DUA89 also accepts and performs I/O requests from applications running on the OpenVMS Cluster system. Once the copy operation completes, a merge operation automatically starts. See Chapter 6 for more information about merge operations.

The next example shows how the SHOW DEVICE command display looks during the merge operation.

$ SHOW DEVICE DSA8
Device               Device        Error    Volume         Free  Trans Mnt
 Name                Status        Count     Label        Blocks Count Cnt
DSA8:                Mounted           0  APPARITION      890937     1   1
 
$11$DUA8:   (HSJ001) ShadowMergeMbr    0  (merging DSA8: 78% merged)
$11$DUA89:  (HSJ002) ShadowMergeMbr    0  (merging DSA8: 78% merged)
 
      

The SHOW DEVICE command produces a display similar to this example when a shadow set is in a transient state because of a merge operation. The merge operation is 78% complete.

$ SHOW DEV D
Device               Device        Error    Volume         Free  Trans Mnt
 Name                Status        Count     Label        Blocks Count Cnt
DSA456:      (FUSS)  Mounted           0  AUDITINGDISK    123189   225  17
$11$DIA1:  (LISBEN)  Online            0
$11$DJA16: (GALEXI)  Online            0
$11$DJA128:(GALEXI)  Mounted wrtlck    0  CORPORATEVOL    164367     1  18
$11$DJA134:(GALEXI)  Mounted           0  WORKVOLUME      250344     1  16
$11$DUA1:    (FUSS)  Mounted           0  MAR24DISKVOL    676890     1  18
$11$DUA2:    (FUSS)  ShadowSetMember   0  (member of DSA456:)
$11$DUA7:   (BLISS)  Online            0  (remote shadow member)
$11$DUA11: (LISBEN)  Mounted           0  RMSFILES        621183     1  18
$11$DUA13:  (BLISS)  Mounted           0  RESIDENTVOL     525375     1  18
 
      

This example shows how the SHOW DEVICE command displays remote shadow set members. In this display, the device $11$DUA7, whose description is "remote shadow member," is a member of a shadow set that is not mounted on this system.

$ SHOW DEVICE/FULL DSA80
Disk DSA80:, device type MSCP served SCSI disk, is online, mounted, file- 
oriented device, shareable, available to cluster, error logging is enabled.
 
Error count                    0    Operations completed               138
Owner process                 ""    Owner UIC                      [SHADOW]
Owner process ID        00000000    Dev Prot    S:RWED,O:RWED,G:RWED,W:RWED
Reference count                1    Default buffer size                512
Total blocks              891072    Sectors per track                   51
Total cylinders             1248    Tracks per cylinder                 14
Volume label         "SHADTEST1"    Relative volume number               0
Cluster size                   3    Transaction count                    1
Free blocks               890937    Maximum files allowed           111384
Extend quantity                5    Mount count                          4
Mount status              System    Cache name         "_DSA2010:XQPCACHE"
Extent cache size             64    Maximum blocks in extent cache   89093
File ID cache size            64    Blocks currently in extent cache     0
Quota cache size               0    Maximum buffers in FCP cache       216
Volume status:  subject to mount verification, file high-water marking,write-
  through caching enabled.
Volume is also mounted on BLASTA, CNASTA, SHASTA.
Disk $255$DUA56:, device type MSCP served SCSI disk, is online, member of 
shadow set DSA80:, error logging is enabled.
Error count                    0    Shadow member operation count      301
Host name               "SHASTA"    Host type, avail      VAX 6000-320,yes
Allocation class             255
  Volume status:  volume is a merge member of the shadow set.
Disk $255$DUA58:, device type MSCP served SCSI disk, is online, member of 
shadow set DSA80:, error logging is enabled.
Error count                    0    Shadow member operation count      107
Host name               "SHASTA"    Host type, avail      VAX 6000-320,yes
Allocation class             255
Volume status:  volume is a merge member of the shadow set.
      

This example shows how the SHOW DEVICE/FULL command displays detailed information about the shadow set and its members. Notice that both members, $255$DUA56 and $255$DUA58, are merge members. Section 4.9.4 shows what this shadow set looks like when it is examined using the System Dump Analyzer.

The System Dump Analyzer (SDA) is a utility provided with the OpenVMS operating system. Although the main function of SDA is for crash dump analysis, it is also a useful tool for examining a running system, including the shadow sets. You can also use SDA to determine whether or not a third-party SCSI device supports the shadowing data repair (disk bad block errors) capability.An example is included in Section 4.9.4.1.

The SDA command SHOW DEVICE displays information from the system data structures that describe the devices in the system configuration. To examine a shadow set, first enter ANALYZE/SYSTEM at the DCL prompt to invoke the System Dump Analyzer. Then at the SDA> prompt, enter the SHOW DEVICE command followed by the virtual unit name.

The following example shows how to obtain information about the shadow set represented by the virtual unit DSA80. Compare the SDA output in the following example with the DCL SHOW DEVICE output shown in the last example in Section 4.9.3.

$ ANALYZE/SYSTEM VAX/VMS System analyzer SDA> SHOW DEVICE DSA80 I/O data structures ------------------- DSA80 HSJ00 UCB address: 810B7F50 Device status: 00021810 online,valid,unload,lcl_valid Characteristics: 1C4D4008 dir,fod,shr,avl,mnt,elg,idv,odv,rnd 00082021 clu,mscp,loc,vrt Owner UIC [004000,000015] Operation count 138 ORB address 810B8080 PID 00000000 Error count 0 DDB address 813F49F0 Alloc. lock ID 009C2595 Reference count 1 DDT address 810BEBB8 Alloc. class 0 Online count 1 VCB address 810BE3F0 Class/Type 01/15 BOFF 0000 CRB address 8129EB10 Def. buf. size 512 Byte count 0200 PDT address 810121A0 DEVDEPEND 04E00E33 SVAPTE 81FDE55C CDDB address 813F4360 DEVDEPND2 00000000 DEVSTS 0004 SHAD address 8111D460 FLCK index 34 RWAITCNT 0000 I/O wait queue empty DLCK address 00000000 Shadow Device status: 0004 nocnvrt ----- Shadow Descriptor Block (SHAD) 8111D460 ----- Virtual Unit status: 0041 normal,merging Members 2 Act user IRPs 0 VU UCB 810B7F50 Devices 2 SCB LBN 0006CC63 Write log addr 00000000 Fcpy Targets 0 Generation Num 28D47C20 Master FL empty Mcpy Targets 2 00935BC7 Restart FL empty Last Read Index 1 Virtual Unit Id 00000000 Master Index 0 12610050 ----- SHAD Device summary for Virtual Unit DSA80 ----- Device $255$DUA56 Index 0 Device Status A6 merge,cip,src,valid UCB 810510D0 VCB 81400A00 Unit Id. 12A10038 000000FF Merge LBN 0004B94D Device $255$DUA58 Index 1 Device Status A6 merge,cip,src,valid UCB 81051260 VCB 81439800 Unit Id. 12A1003A 000000FF Merge LBN 0004B94D SDA> exit

The SDA utility's SHOW DEVICE command first displays device characteristics of the DSA80 virtual unit and the addresses of data structures. SDA then displays the DSA80 virtual unit status and the status of the individual shadow set members. Notice how the device status for each member reflects that the unit is in a merge state. For example, $255$DUA56 is shown with the following device status:

Device $255$DUA56 Index 0 Device Status A6 merge (1), cip (2), src (3), valid (4) UCB 810510D0 VCB 81400A00 Unit Id. 12A10038 000000FF Merge LBN 0004B94D

This information translates to the following:

1. merge---$255$DUA56 is marked for a merge operation.
2. cip---Copy in progress. In this example, a merge operation is in progress.
3. src---$255$DUA56 is considered a source member for the read operations.
4. valid---The SCB information on $255$DUA56 is considered valid.

Notice also how both devices $255$DUA56 and $255$DUA58 show that, at the time the SDA took this "snapshot" of the shadow set, the merge operation is merging at LBN 0004B94D.

The following example shows an SDA display of the same shadow set when $255$DUA56 is a merge member and $255$DUA58 is the recipient of a copy operation. A shadow set can be in this merge/copy state when a node that has the shadow set mounted crashes while a member in the shadow set is undergoing a copy operation. Volume shadowing automatically marks the member undergoing the copy operation so that it receives a merge operation after the copy operation completes. This ensures consistency across the shadow set.

The example first shows output for one shadow set member, using the DCL command SHOW DEVICE $255$DUA58; then the example shows the output for the entire shadow set, using the SDA command SHOW DEVICE DSA80. (SDA is invoked by the ANALYZE/SYSTEM command.)

$ SHOW DEVICE $255$DUA58 Device Device Error Volume Free Trans Mnt Name Status Count Label Blocks Count Cnt DSA80: Mounted 0 SHADTEST1 890937 1 3 $255$DUA56: (SHASTA) ShadowMergeMbr 0 (merging DSA80: 0% merged) $255$DUA58: (SHASTA) ShadowCopying 0 (copy trgt DSA80: 9% copied ) $ ANALYZE/SYSTEM VAX/VMS System analyzer SDA> SHOW DEVICE DSA80 I/O data structures ------------------- DSA80 RA81 UCB address: 810B7F50 Device status: 00021810 online,valid,unload,lcl_valid Characteristics: 1C4D4008 dir,fod,shr,avl,mnt,elg,idv,odv,rnd 00082021 clu,mscp,loc,vrt Owner UIC [004000,000015] Operation count 130 ORB address 810B8080 PID 00000000 Error count 0 DDB address 813F49F0 Alloc. lock ID 009C2595 Reference count 1 DDT address 810BEBB8 Alloc. class 0 Online count 1 VCB address 810BE3F0 Class/Type 01/15 BOFF 0000 CRB address 8129EB10 Def. buf. size 512 Byte count 0000 PDT address 810121A0 DEVDEPEND 04E00E33 SVAPTE 00000000 CDDB address 813F4360 DEVDEPND2 00000000 DEVSTS 0004 SHAD address 8111D460 FLCK index 34 RWAITCNT 0000 I/O wait queue empty DLCK address 00000000 Shadow Device status: 0004 nocnvrt ----- Shadow Descriptor Block (SHAD) 8111D460 ----- Virtual Unit status: 0061 normal,copying,merging Members 1 Act user IRPs 0 VU UCB 810B7F50 Devices 2 SCB LBN 0006CC63 Master FL empty Fcpy Targets 1 Generation Num 7B7BE060 Restart FL empty Mcpy Targets 0 00935BC4 Last Read Index 0 Virtual Unit Id 00000000 Master Index 0 12610050 ----- SHAD Device summary for Virtual Unit DSA80 ----- Device $255$DUA56 Index 0 Device Status A2 merge,src,valid UCB 810510D0 VCB 81400A00 Unit Id. 12A10038 000000FF Merge LBN FFFFFFFF Device $255$DUA58 Index 1 Device Status 87 fcpy,merge,cip,valid UCB 81051260 VCB 81439800 Unit Id. 12A1003A 000000FF Copy LBN 00033671

In this example, in the SHAD Device summary for Virtual Unit DSA80 display, the device status ( fcpy ) for $255$DUA58 shows that it is the target of a full copy operation. The source of the operation is $255$DUA56; notice that the Merge LBN line for $255$DUA56 shows a series of Fs ( FFFFFFFF ). This notation indicates that a merge operation must be done after the copy operation completes. The Copy LBN line for the target disk $255$DUA58 shows that the copy operation is currently copying at LBN 00033671.

4.9.4.1 Using SDA to Obtain Information About Third-Party SCSI Devices

When you mount a SCSI disk, the SCSI disk class driver, DKDRIVER, checks the device-specific parameters to see whether the disk supports READL/WRITEL commands.

If a SCSI disk does not support READL and WRITEL commands, DKDRIVER sets a NOFE (no forced error) bit to indicate that the disk cannot support the shadowing data repair (disk bad block errors) capability. You can use the SDA command SHOW DEVICE to check for the NOFE flag in the Characteristics field of the SDA display.

$ ANALYZE/SYSTEM SDA> SHOW DEVICE DKA300:(1) I/O data structures ------------------- COLOR$DKA300 Generic_DK UCB address: 80A665E0 Device status: 00000010 online Characteristics: 1C454008 dir,fod,shr,avl,elg,idv,odv,rnd 05010281 clu,srv,nnm,scsi,nofe(2) . . .

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