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HP OpenVMS Systems Documentation

HP OpenVMS DCL Dictionary

SHOW SHADOW (Alpha/I64 Only)

Displays the status of a specified shadow set on the system.
If no qualifiers are specified, displays a summary of the device.

Format

SHOW SHADOW [DSAn[:]]

Parameter

DSAn[:]
Specifies the virtual unit name of the shadow set for which information is to be displayed.
If no virtual unit is specified, information is displayed for all mounted shadow sets.

Qualifiers

/ACTIVE
Displays one of three possible states:

Merge or Copy is not required
Copy is in progress on node node-name, n% completed
Merge is in progress on node node-name, n% completed

/BY_PRIORITY

/BY_PRIORITY DSAn:
Displays a list of shadow sets on the system, sorted in the order in which a recovery operation (copy, full merge, or minimerge) is scheduled to occur. If a copy or merge is active, the display shows on which system it is occurring. This list is specific to the system on which the command is executed, so the list might vary across systems in a cluster. Higher numbers indicate a higher priority.
Tip: When the command specifies a virtual unit (DSAn:), the display shows the current priority and status of just this virtual unit. If any copy or merge operations are in progress, the system on which the operation is occurring is also displayed, along with the operation's progress.
/COPY
Displays one of three possible states:

Copy is not required
Copy is pending
Copy is in progress on node node-name, n% completed

/FULL
Displays complete information about the specified devices (or all devices if no device is specified). The only other qualifier that can be specified with /FULL is /OUTPUT.
/MERGE
Displays one of three possible states:

Merge is not required
Merge is pending
Merge is in progress on node node-name, n% completed

/NAME[=policy-name]
Used with /POLICY=HBMM to display the characteristics of a specific, named host-based minimerge (HBMM) policy or, if no policy name is specified, all named HBMM policies on the cluster.
/OUTPUT[=filespec]
Outputs any messages to the specified file.
/POLICY=HBMM
Displays the host-based minimerge (HBMM) policy associated with the specified devices.
HBMM is the only value supported for /POLICY, and it must be included.
If the command is issued with no device specification, information is output for all devices. There might be a noticeable delay between the output of device information or before returning to the DCL command prompt. This delay is normal.
/SITE=n
Displays every shadow set member device (and the virtual device of which it is a member) that has the site value specified by n.

Examples

$ SHOW SHADOW DSA112:
_DSA112:  Volume Label: DSA112
  Virtual Unit State:   Steady State
  No Enhanced Shadowing Features in use
  VU Timeout Value      1200    VU Site Value          0
  Copy/Merge Priority   5000    Mini Merge      Disabled
  Served Path Delay     30
  Device $1$DGA112              Master Member
    Read Cost             2     Site 0
    Member Timeout        180
  Device $1$DGA113
    Read Cost             2     Site 0
    Member Timeout        180

This display is for a shadow set that is in a steady state. That is, there are no active or pending merges or copy operations for this shadow set and HBMM has not been enabled.

$ SHOW SHADOW DSA112:
_DSA112:  Volume Label: DSA112
  Virtual Unit State: MiniMerge Active (5%), Copy Pending (32%) on NODE1
  Enhanced Shadowing Features in use:
      Host-Based Minimerge (HBMM)
  VU Timeout Value      1200    VU Site Value          0
  Copy/Merge Priority   5000    Mini Merge       Enabled
  Served Path Delay     30
  HBMM Policy
    HBMM Reset Threshold: 50000
    HBMM Master lists:
      Up to any 6 nodes in the cluster
    HBMM bitmaps are active on NODE1,NODE2
    Modified blocks since bitmap creation: 137033
  Device $1$DGA112              Master Member, Merging (5%)
    Read Cost             2     Site 0
    Member Timeout        180
  Device $1$DGA113              Copy Target (32%)
    Read Cost             2     Site 0
    Member Timeout        180

This display is for a shadow set that is enabled for HBMM. A shadow set member copy and a shadow set merge are required for this shadow set. The shadow member copy was 32% complete when a merge became necessary. Because the merge was a minimerge, it preempted the copy and the status of the copy now displays as pending.

$ SHOW SHADOW DSA12

_DSA12:   Volume Label: DGA12
  Virtual Unit State: Merge Active (23%), Copy Pending (3%) on NODE1
  Enhanced Shadowing Features in use:
      Host-Based Minimerge (HBMM)

  VU Timeout Value      300     VU Site Value          5
  Copy/Merge Priority   5000    Mini Merge       Enabled
  Served Path Delay     0
  HBMM Policy
    HBMM Reset Threshold: 50000
    HBMM Master lists:
      Up to any 2 of the nodes: NODE1,NODE2
    HBMM bitmaps are active on the following nodes: NODE2,NODE1
  Modified blocks since bitmap creation: 254
  Device $1$DGA12               Master Member, Merging (23%)
    Read Cost             2     Site 5
    Member Timeout        180

  Device $1$DGA22               Copy Target (3%)
    Read Cost             2     Site 0
    Member Timeout        180


  Device $1$DGA32               Merging (23%)
    Read Cost             2     Site 0
    Member Timeout        180

This example displays status information for shadow set DSA12. A minimerge operation takes precedence over a copy operation, so the copy has been stopped at 3 percent and the merge is now active and 23 percent completed.
Note that the VU site value and the site value for device $1$DGA12 are both 5. Therefore, read I/O to DSA12 on this system is directed to $1$DGA12.

$ SHOW SHADOW /BY_PRIORITY
Device    Mbr                                        Active
 Name     Cnt  Priority Virtual Unit State          on Node
_DSA30:    2     5000   Steady State
_DSA12:    3     4000   Steady State
_DSA234:         3000   Not Mounted on this node
Total of 2 Operational shadow sets; 0 in Mount Verification; 1 not mounted

The display resulting from this command shows that device DSA30 (with a priority of 5) will start a copy or merge operation on this system before DSA12 (with a priority of 4). It also shows that DSA30 is a two-member shadow set and that DSA12: is a three-member shadow set.
The last line of the display summarizes all the shadow sets and their states, including shadow sets that have exceeded their mount verification timeout limits. Operational shadow sets are shadow sets that are mounted with one or more members and that may or may not have copy or merge operations in progress. These shadow sets are available to applications for reads and writes.

$ SHOW SHADOW /BY_PRIORITY
Device  Mbr                                               Active
 Name   Cnt Priority Virtual Unit State                  on Node
_DSA30: 2+1   5000   Merge Pending (23%), Copy Active (5%) NODE1
_DSA12:  2    4000   Steady State
_DSA234:      3000   Not Mounted on this node
Total of 2 Operational shadow sets; 0 in Mount Verification; 1 not mounted

This display shows that a copy is being performed on system NODE1 and is 5 percent done. The member count (Mbr Cnt) of 2+1 indicates that there are two source members in the shadow set and another member is being added. The shadow set had completed 23 percent of a merge when the third member was added. When the copy operation is complete, the merge will resume from that point.

#6
$ SHOW SHADOW /BY_PRIORITY DSA11 Device Mbr Active Name Cnt Priority Virtual Unit State on Node _DSA11: 3 5000 Merge Active (29%) NODE3

This command displays the status of only DSA11, which is 29 percent through a merge operation on NODE3.

#7
$ SHOW SHADOW /MERGE Device Volume Name Status _DSA1010: FOOBAR Merge Pending (23%), Copy Active (77%) on NODE1

This command requests the status of a merge operation. The display provides the status of the merge, but also reveals that a copy operation is currently active.

#8
$ SHOW SHADOW DSA1010 /ACTIVE Device Volume Name Status _DSA1010: FOOBAR Merge Active (25%) on NODE1

The copy shown to be in progress in the previous example has completed; now the merge has resumed and is 25 percent done. NODE1 is doing the merge.

$ SHOW SHADOW DSA1010

_DSA1010: Volume Label: FOOBAR
  Virtual Unit State:   Merge Pending (0%)
  Enhanced Shadowing Features in use:
      Host-Based Minimerge (HBMM)

  VU Timeout Value      3600    VU Site Value          0
  Copy/Merge Priority   5000    Mini Merge      Disabled
  Served Path Delay     30
  Device $252$DUA610            Master Member Merging (0%)
    Read Cost             2     Site 0
    Member Timeout        10
  Device $252$DUA1010     Merging (0%)
    Read Cost             2     Site 0
    Member Timeout        10
  Device $252$DUA716      Merging (0%)
    Read Cost             2     Site 0
    Member Timeout        10

In this example, another event has caused the set to go into a merge state. However, this set is not currently being acted on --- perhaps because the system does not have any more SHADOW_MAX_COPY threads or because the relative priority of this shadow set is lower, causing other merges to be completed first. When a system is able to perform the merge, the word Active appears in the display and the Merging percent begins to increase.)

#10

$ SHOW SHADOW DSA12 /POLICY=HBMM
  HBMM Policy for device _DSA12:
    HBMM Reset Threshold: 50000
    HBMM Master lists:
      Up to any 2 of the nodes: NODE1,NODE2,NODE3
    HBMM bitmaps are active on the following nodes: NODE2,NODE1
  HBMM Reset Count      4      Last Reset  9-JAN-2004 13:40:11.45
  Modified blocks since last bitmap reset: 142367

This command displays host-based minimerge (HBMM) information for device DSA12.
In this example, an HBMM policy has been defined for DSA12. No more than two of the systems NODE1 and NODE2 can have master bitmaps for DSA12 at any time. The bitmap is reset when the bitmap has bits set to represent a total of 50000 blocks written to DSA12. When this command was entered, both NODE1 and NODE2 had master bitmaps.
Note that the "modified blocks" value exceeds that of the reset threshold. This can happen because the bitmap is not reset immediately upon crossing the reset threshold. The reset threshold is checked periodically, and the interval for checking the reset threshold is controlled by the system parameter SHADOW_HBMM_RTC; the default is 150 seconds.

#11

$ SHOW SHADOW/POLICY=HBMM/NAME=PEAKS_ISLAND
   HBMM Policy PEAKS_ISLAND
     HBMM Reset Threshold: 50000
     HBMM Master lists:
       Up to any 2 of the nodes: NODE1,NODE2,NODE3
       Any 1 of the nodes: NODE4,NODE5
       Up to any 2 of the nodes: NODE6,NODE7,NODE8

This command displays the HBMM named policy PEAKS_ISLAND.

#12

$ SHOW SHADOW /POLICY=HBMM
   HBMM Policy for device _DSA12:
     HBMM Reset Threshold: 50000
     HBMM Master lists:
       Up to any 2 of the nodes: NODE1,NODE2
     HBMM bitmaps are active on NODE1,NODE2
   Modified blocks since bitmap creation: 254
   HBMM Policy for device _DSA30:
     HBMM Reset Threshold: 50000
     HBMM Master lists:
       Up to any 2 of the nodes: FLURRY,FREEZE,HOTTUB
   HBMM Policy for device _DSA99:
     HBMM Reset Threshold: 50000
     HBMM Master lists:
       Up to any 2 of the nodes: NODE1,NODE2,NODE3
       Any 1 of the nodes: NODE4,NODE5
       Up to any 2 of the nodes: ICEBAR,SWEDEN,MILANO
   HBMM Policy for device _DSA999:
     HBMM Reset Threshold: 50000
     HBMM Master lists:
       Up to any 2 of the nodes: NODE1,NODE2,NODE3
       Any 1 of the nodes: NODE4,NODE5
       Up to any 2 of the nodes: ICEBAR,SWEDEN,MILANO

The command in this example displays a list of all shadow sets that have HBMM policies.

#13

$ SHOW SHADOW /POLICY=HBMM /NAME
  HBMM Policy PEAKS_ISLAND
    HBMM Reset Threshold: 50000
    HBMM Master lists:
      Up to any 2 of the nodes: NODE1,NODE2,NODE3
      Any 1 of the nodes: NODE4,NODE5
      Up to any 2 of the nodes: NODE6,NODE7,NODE8
  HBMM Policy POLICY_1
    HBMM Reset Threshold: 50000
    HBMM Master lists:
      Up to any 2 of the nodes: NODE1,NODE2,NODE3
      Any 1 of the nodes: NODE4,NODE5
  HBMM Policy ICE_HOTELS
    HBMM Reset Threshold: 50000
      Up to any 2 of the nodes: QUEBEC,SWEDEN,FINLND
      Any 1 of the nodes: ALASKA,GRNLND

The command in this example displays a list of all named HBMM policies on the cluster.

#14
$ SHOW SHADOW DSA12 /OUTPUT=DSA12_OUTPUT.LIS

The output of this SHOW SHADOW command is directed to the file named DSA12_OUTPUT.LIS.

#15

$ SHOW SHADOW DSA12 /FULL

_DSA12:   VolumeLabel: DGA12
  Virtual Unit State:  Steady State
  Enhanced Shadowing Features in use:
      Host-Based Minimerge (HBMM)

  Cluster Virtual Unit Status: 0001 - normal
  Local Virtual Unit Status: 00000110 - Local Read,Policy Active
  Total Devices         2       VU_UCB          81435180
  Source Members        2       SCB LBN         003FEB5F
  Act Copy Target       0       Generation      00A2BA31
  Act Merge Target      0        Number         441DA800
  Last Read Index       0       Master Mbr Index       0
  Copy Hotblocks        0       Copy Collisions        0
  SCP Merge Repair Cnt  0       APP Merge Repair Cnt   0
  VU Timeout Value      300     VU Site Value          0
  Copy/Merge Priority   5000    Mini Merge       Enabled
  Served Path Delay     0
  HBMM Policy
    HBMM Reset Threshold: 50000
    HBMM Master lists:
      Up to any 2 of the nodes: XYZ100,XYZ200
    HBMM bitmaps are active on the following nodes: XYZ200,XYZ100
  Modified blocks since bitmap creation: 254
  Device $1$DGA12               Master Member
    Index 0 Status  000000A0    src,valid
    Ext. Member Status    00
    Read Cost             2     Site 0
    Member Timeout        180   UCB  81643840
  Device $1$DGA22
    Index 1 Status  000000A0    src,valid
    Ext. Member Status    00
    Read Cost             2     Site 0
    Member Timeout        180   UCB  81642840

  Device $1$DGA32
    Index 1 Status 000000A0     src,valid
    Ext. Member Status    00
    Read Cost             2     Site  0
    Member Timeout        180   UCB  81641840

This example shows a full information display for device DSA12.

#16

$ SHOW SHADOW DSA0 /FULL
_DSA0:    Volume Label: TOPAZ_XA7V
  Virtual Unit State:   Steady State
  Cluster Virtual Unit Status: 0001 - normal
  Local Virtual Unit Status: 00000110 - enforce_local_read,
hbmm_eval_policy_enabled

  Enhanced Shadowing Features in use:
        Dissimilar Device Shadowing (DDS)
        Host-Based Minimerge (HBMM)

  Total Devices            2    VU_UCB          817AFD80
  Source Members           2    SCB LBN         001F5C50
  Act Copy Target          0    Generation      00A31141
  Act Merge Target         0     Number         C6925F29
  Last Read Index          0    Master Mbr Index       0
  Copy Hotblocks           0    Copy Collisions        0
  SCP Merge Repair Cnt     0    APP Merge Repair Cnt   0
  VU Timeout Value      3600    VU Site Value          0
  Copy/Merge Priority   5000    Mini Merge       Enabled
  Served Path Delay       30

  HBMM Policy
    HBMM Reset Threshold: 50000
    HBMM Master lists:
      Up to any 6 nodes in the cluster
    HBMM bitmaps are active on ABCD2,ABCD1
    Modified blocks since bitmap creation: 254

  Device $252$DKA0              Master Member
    Index 0 Status  000000A0    mbr_src,mbr_valid
    Ext. Member Status    00
    Read Cost              2    Site 0
    Member Timeout       120    UCB  8163D880

  Device $252$DKA100
    Index 1 Status  000000A0    mbr_src,mbr_valid
    Ext. Member Status    00
    Read Cost              2    Site 0
    Member Timeout       120    UCB  8163E880

This example shows sample output when both HBMM and Dissimilar Device Shadowing are in use.

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