HP Volume Shadowing for OpenVMS: OpenVMS Version 8.4 > Chapter 4 Creating and Managing Shadow Sets Using DCL Commands

Managing Copy and Merge Operations (Integrity servers and Alpha)

spacerspacerspacer
spacer
spacer
  		 
 

Copies and merges performed by the volume shadowing software are regulated automatically by the locking software and by the setting of SHADOW_MAX_COPIES. The SET SHADOW command, introduced in OpenVMS Alpha Version 7.3–2 and extended in OpenVMS Version 8.2, provides better control over the order of copies and merges and allows you to specify the systems on which the copy operations must take place.

All SET SHADOW qualifiers pertain to shadow sets (DSAn:), and some can also be applied to individual shadow set members (ddcu:), as described in Table 4-3. For most qualifiers that take a shadow set as a parameter, the /ALL qualifier can be used in place of the shadow set name to indicate that the requested action applies to all shadow sets on the system.

The qualifiers remain in effect until the device (shadow set or shadow set member) is dismounted. If the device is remounted (in the case of a shadow set member, returned to the shadow set from which it was dismounted), the qualifier must be specified again. The SET SHADOW command requires the SYSPRV privilege.

NOTE: The qualifiers /DELETE, /DISABLE, /ENABLE, /NAME, and /POLICY are used only to manage host-based minimerge (HBMM) operations and do not apply to other operations. If you specify any other (non-HBMM) qualifiers in a command that includes HBMM qualifiers, the command fails. For more information about HBMM, see Chapter 8.

The following example shows how to specify qualifiers for a shadow set:

$ SET SHADOW DSAn:/qualifier/qualifier

Table 4-3 SET SHADOW Command Qualifiers

Qualifier

Function

/ABORT_VIRTUAL_

UNIT {DSAn:|/ALL}

Aborts mount verification on the specified shadow set or on all shadow sets in mount verification on the system. Use this qualifier when you know that the unit cannot be recovered. When you use this qualifier, the shadow set must be in mount verification. The shadow set aborts mount verification immediately on the system from which the command is issued. If the shadow set is not in mount verification, this command returns the error %SYSTEM-E-UNSUPPORTED, unsupported operation or function.

After this command completes, the shadow set must still be dismounted. Use the following command to dismount the shadow set: 

$ DISMOUNT/ABORT/OVERRIDE=CHECKS  DSAn

/ALL

Causes the command to operate on all shadow sets that are mounted on the system from which the command is issued.

/ALL can be used instead of DSAn:in most commands that take a shadow set device specification as a parameter, except with the /DEMAND_MERGE, /DELETE, /EVALUATE=RESOURCES, and /POLICY qualifiers or with any qualifier that operates only on individual shadow set members (for example, /MEMBER_TIMEOUT and /FORCE_REMOVAL.

/CONFIRM/NOCONFIRM (default)

Specifies whether a query is made before each merge operation to confirm that the operation must be performed on the designated shadow set.This qualifier can be used only in conjunction with the /DEMAND_MERGE qualifier.The following responses are valid in response to the query:

  • Affirmative: YES, TRUE, or 1.

  • Negative: NO, FALSE, 0 (zero), or pressing the Return key.

  • End the process: QUIT or Ctrl/Z.

  • When you enter ALL, the command continues to process, but no further prompts are given.

You can enter word responses in uppercase or lowercase letters, and words can be abbreviated to one or more letters. If you enter an illegal response, DCL redisplays the prompt. For examples, see the SET SHADOW examples in the HP OpenVMS DCL Dictionary.

/COPY_SOURCE {ddcu:|DSAn:|/ALL}

Specifies which source member of a shadow set to use as the source for read data during full copy operations when a third member is added to a shadow set that contains two full members. This qualifier affects only those copy operations that do not use disk copy data (DCD) commands. The source specified by this qualifier persists until the shadow set is dismounted.Some storage controllers, such as the HSG80, have a read-ahead cache, which significantly improves a device’s read performance. Copy operations normally alternate reads between the two source members, which effectively nullifies the benefits of the read-ahead cache. This qualifier lets you force all reads from a single, specified source member for the duration of a copy operation.In addition to improving copy performance, /COPY_SOURCE can be used to prevent read operations from a specific shadow set member that is considered unreliable. By specifying only the reliable shadow set member, the copy operations can continue to completion. The unreliable shadow set member can be removed once the copy operation completes successfully. If a shadow set (DSAn) is specified, all reads for full copy operations are performed from the device that is the current "master" member, regardless of physical location of the disk.If a shadow set member (ddcu:) is specified, that member is used as the read source for all copy operations. This setting allows you to choose any source member. For example, you can choose a source member that is at the same site as the member being added, rather than using a master member that is not at the same site. If /ALL is specified, all reads for full copy operations on all currently mounted virtual units are performed from the master member.

/DELETE {DSAn:|/NAME}

Used only in conjunction with /POLICY=HBMM, /DELETE removes a host-based minimerge (HBMM) policy from a specified shadow set, or deletes an HBMM named policy from the entire cluster. For example, the following command removes the policy that is currently associated with shadow set DSA1:

$ SET SHADOW /DELETE DSA1 /POLICY=HBMM

In contrast, the following command removes COMPANY_POLICY from the cluster:

$ SET SHADOW /DELETE /NAME=COMPANY_POLICY /POLICY=HBMM

You cannot delete the NODEFAULT policy, nor can you specify /ALL with /DELETE.

/DEMAND_MERGE

Initiates a merge operation on the specified shadow set. This qualifier is useful if the shadow set was created with the INITIALIZE/SHADOW command without the use of the /ERASE qualifier. For more information about using /DEMAND_MERGE, see “Using /DEMAND_MERGE to Start a Merge Operation”.

You cannot specify /ALL with /DEMAND_MERGE.

An OPCOM message is displayed for each shadow set indicating that a demand merge has been invoked and recording the process ID (PID) of the process that executed the command. For example:

%%%%%%%%%%% OPCOM 9-MAR-2004 10:35:23.24 %%%%%%%%%%%

Message from user SYSTEM on NODE1

Demand Merge requested for _DSA721:, PID: 2760009A

/DISABLE=HBMM {DSAn:| /ALL}

Disables host-based minimerge (HBMM) on the specified shadow set or clusterwide on all shadow sets.

HBMM is the only supported value for /DISABLE, and it must be included.

/DISABLE=SPLIT_READ_LBNS

Disables the split behavior of LBNs and as a result the reads are alternated between the source shadow set members having the same read_cost and device queue length.

/ENABLE=HBMM

Enables host-based minimerge (HBMM) on the specified shadow set or across the entire cluster if an applicable HBMM policy exists.

HBMM is the only supported value for /DISABLE, and it must be included.

/ENABLE=SPLIT_READ_LBNS

Logically divides the shadow set members having the same read cost into equal groups of LBNs. When a virtual unit performs a read, it does so by reading from the corresponding LBN group. This results in the maximum usage of the controller read-ahead cache.

/EVALUATE=

RESOURCES

Forces the system to evaluate whether it must act on most shadow copy and merge operations currently being managed on the system. It cancels most operations and then, based on the value of system parameter SHADOW_MAX_COPY and the copy/merge priority of each shadow set, it evaluates the order in which the pending copies and merges should be restarted.

RESOURCES is the only supported value for /EVALUATE, and it must be included.

EVALUATE does not apply to MSCP-based minimerge operations. MSCP-based minimerge operations are not subject to cancellation and restart by /EVALUATE.

This command is intended to be used after changing the value of the dynamic system parameter SHADOW_MAX_COPY or after issuing a SET SHADOW /PRIORITY=n command for a shadow set. After a suitable delay, all available SHADOW_MAX_COPY slots on the system are allocated using the priority list.

/FORCE_REMOVAL ddcu

Expels the specified shadow set member from the shadow set. The specified device must be a member of a shadow set that is mounted on the system where the command is issued. You cannot specify /ALL with /FORCE_REMOVAL.

If connectivity to a device has been lost and the shadow set is in mount verification, this qualifier causes the member to be expelled from the shadow set immediately.

If the shadow set is not currently in mount verification, no immediate action is taken. If connectivity to a device has been lost but the shadow set is not in mount verification, this qualifier lets you flag the member to be expelled from the shadow set as soon the shadow set enters mount verification. If no action has been taken on the specified member and you wish to clear the flag, use /NOFORCE_REMOVAL.

If the shadow set is dismounted before the member is expelled, the FORCE_REMOVAL request expires.

/LOG

Instructs the volume shadowing software to display a brief message confirming that the SET SHADOW command completed. If /OUTPUT is also specified, this information is written to the output file.

/MEMBER_TIMEOUT =n ddcu:

Specifies the timeout value to be used for a shadow set member. The specified device must be a member of a shadow set that is mounted on the system where the command is issued.

The value supplied by this qualifier overrides the system parameter SHADOW_MBR_TMO for this specific device. Each member of a shadow set can be assigned a different MEMBER_TIMEOUT value.The valid range for n is 1 to 16777215 seconds.

The timeout value set by /MEMBER_TIMEOUT does not persist after the shadow set is dismounted.

/MVTIMEOUT {= n DSAn:|=n /ALL}

Specifies the mount verification timeout value to be used for all shadow sets on the cluster or for the shadow set, specified by its virtual unit name (DSAn:). The specified shadow set must be mounted on the system where the command is issued. The value supplied by this qualifier overrides the value specified by the system parameter MVTIMEOUT for this specific shadow set.

NOTE: You cannot change the value of MVTIMEOUT for a system disk. Any attempt to do so results in an error.

The valid range for n is 1 to 16777215 seconds.

The timeout value set by /MVTIMEOUT does not persist after the shadow set is dismounted.

/NAME=policy-name

Used with /POLICY=HBMM to define a named host-based minimerge (HBMM) policy or used with /DELETE to delete a policy. The policy is defined clusterwide. See detailed descriptions under /DELETE and /POLICY.

Policy names are case insensitive and must consist of 1 to 64 characters. Only letters, numbers, the dollar sign ($), and the underscore (_) are allowed.

If you create a default policy, you must assign it the name DEFAULT.

For details about creating and using policy names, see Chapter 8: “Host-Based Minimerge (HBMM) ”.

/OUTPUT= file-name

Outputs any messages to the specified file.

/POLICY=HBMM {=policy-name| =policy-specification}

Creates or deletes a policy for host-based minimerge (HBMM).

HBMM is the only supported value for the /POLICY qualifier, and it must be included. You can optionally specify a named policy, including DEFAULT, or you can specify NODEFAULT to indicate that the shadow set to which it is applied is not to use HBMM, including any DEFAULT policy. For information about specifying policies and using the DEFAULT and NODEFAULT names, see Chapter 8: “Host-Based Minimerge (HBMM) ”.

When /POLICY is specified with /DELETE, it removes either a specified HBMM named policy or the HBMM policy for a specific shadow set. You cannot delete the NODEFAULT policy.

When /POLICY is specified with /NAME, it defines a clusterwide named policy. When no qualifiers others than /NAME and /DELETE are specified, /POLICY defines a policy for a specific shadow set.

Deleting bitmaps with the DELETE/BITMAP command causes a bitmap to be deleted. However, the shadowing software recognizes this condition and starts a new bitmap immediately. To disable HBMM bitmaps, you must use the command SET SHADOW/DISABLE=HBMM.

When defining a policy, you use five keywords (MASTER_LIST, COUNT, RESET_ THRESHOLD, MULTIUSE, and DISMOUNT) to control the placement and management of HBMM bitmaps. An HBMM policy specification consists of a list of these keywords enclosed within parentheses. Only the MASTER_LIST keyword is required. If the COUNT and RESET_THRESHOLD keywords are omitted, default values are applied.

The MULTIUSE and DISMOUNT keywords specify the number of bitmaps to be converted to multiuse bitmaps during the automatic and manual removal of members respectively. If MULTIUSE is omitted, the automatic minicopy on volume processing is not enabled. As a result, none of the HBMM bitmaps are converted to multiuse bitmaps. If DISMOUNT is omitted, a maximum of six HBMM bitmaps can be used as multiuse bitmaps.

 

  • MASTER_LIST=list

    The MASTER_LIST keyword is used to identify a set of systems as candidates for a master bitmap. The list value can be a single system name; a parenthesized, comma-separated list of system names; or the wildcard character, as shown in the following examples:

    MASTER_LIST=Node1
    MASTER_LIST=(NODE1,NODE2,NODE3)
    MASTER_LIST=*

    When the system list consists of a single system name or the wildcard character, parentheses are optional.

    An HBMM policy must include at least one MASTER_LIST. Multiple master lists are optional. If a policy has multiple master lists, the entire policy must be enclosed with parentheses, and each constituent master list must be separated by a comma as shown in the following example:

    (MASTER_LIST=(NODE1,NODE2),MASTER_LIST=(NODE3,NODE4))

    There is no significance to the position of a system name in a master list.

  • COUNT=n

    The COUNT keyword specifies the number of systems in the master list that can have master bitmaps. Therefore, the COUNT keyword and its associated MASTER_LIST must be enclosed within a single parenthetical statement.

    The COUNT value specifies the number of systems on which you want master bitmaps. It does not necessarily mean that the first n systems in the list are chosen.

    When the COUNT keyword is omitted, the default value is six or the number of systems in the master list, whichever is smaller.

    You cannot specify more than one COUNT keyword per master list. Examples:

    (MASTER_LIST=(NODE1,NODE2,NODE3), COUNT=2
    (MASTER_LIST=(NODE1,NODE2,NODE3),COUNT=2),
    (COUNT=2, MASTER_LIST=(NODE4,NODE5,NODE6))
 

  • RESET_THRESHOLD=n

    The RESET_THRESHOLD keyword specifies the number of blocks that can be set before the bitmap can be cleared. Each set bit in a master bitmap corresponds to a set of blocks to be merged, so this value can affect the merge time.

    Bitmaps are eligible to be cleared when the RESET_THRESHOLD is exceeded. However, the reset does not occur immediately when the threshold is crossed. For more information about selecting a value for this attribute, see the OpenVMS Support for Host-based Minimerge (HBMM) document.

    The reset threshold is associated with a specific HBMM policy. Therefore, the RESET_THRESHOLD keyword can be defined only once in a policy specification. Because its scope is the entire policy, the RESET_THRESHOLD keyword cannot be specified inside a constituent master list when the policy uses multiple master lists.

    When the RESET_THRESHOLD keyword is omitted, the value of 1,000,000 is used by default.

    Example:

    (MASTER_LIST=*, COUNT=4, RESET_THRESHOLD=100000)

In a policy with multiple master lists, a given system name can appear in only one master list. A shadow set need not be mounted to have an HBMM policy defined for it. For more /POLICY examples, see the SET SHADOW Examples section in the HP OpenVMS DCL Dictionary .

 

  • MULTIUSE=n

    The MULTIUSE keyword enables automatic minicopy on volume processing. n specifies the number of existing HBMM master bitmaps to be converted to MULTIUSE bitmaps in the event that a shadow set member is removed from the shadow set by the shadowing driver.

    During loss of connectivity to a site or controller, shadowing may remove a member from the shadow set. When the member is added back to the shadow set, a full shadow copy occurs.

    By converting a few of the HBMM bitmaps to multiuse bitmaps, all the writes that are performed to the shadow set are recorded. Thus, when the member is added back to the shadow set, the multiuse bitmap can be used for a minicopy operation. This is much faster than a full copy operation.

    The value of n cannot exceed the implied or explicit value of COUNT. If MULTIUSE is not specified, bitmaps are not converted to multiuse and a full copy operation is required. Fatal drive errors that remove a shadow set member do not cause a multiuse conversion because the drive must be replaced, and therefore requires a full copy operation. For more information, see “Multiuse Property for Host-Based Minicopies”

  • DISMOUNT=n

    The DISMOUNT keyword allows all the 12 write bitmaps to be used by Shadowing as multiuse bitmaps, thereby reducing the single point of failure of single minicopy master bitmaps. n specifies the number of HBMM bitmaps to be converted to multiuse bitmaps every time a member is dismounted from a shadow set using the following command:

    DISMOUNT/POLICY=MINICOPY

/PRIORITY=n DSAn:

Overrides the current default priority setting. Priorities range from 0 (lowest) to 10000 (highest). The default priority is 5000. A shadow set with a priority of 0 is never considered for a merge or a copy on the system. When a recovery operation (that is, either a merge or a copy) is needed on multiple shadow sets, the shadow sets are recovered in priority order from highest to lowest. The priority setting is system specific; any change in priority made on a single system does not propagate to the entire cluster and does not persist across a system reboot. Once this qualifier has been applied to a shadow set that is mounted, the setting persists across any subsequent DISMOUNT and MOUNT commands.

For more information about using this qualifier, see “Prioritizing Merge and Copy Operations”.

/READ_COST =n {ddcu:|DSAn:}

Enables you to modify the default “cost” assigned to each shadow set member (ddcu:). By modifying the assignments, you can bias the reads in favor of one member of a two-member shadow set, or, in the case of three-member shadow sets, in favor of one or two members of the set over the remaining members. The device specified must be a member of a shadow set that is mounted on the node where the command is issued.

The valid range for the specified cost (n) is 1 to 65,535 units. You cannot specify /ALL with /READ_COST.

The shadowing driver assigns default READ_COST values to shadow set members when each member is initially mounted. The default value depends on the device type and its configuration relative to the system mounting it. The following list of device types is ordered by the default READ_COST assignments, from the lowest cost to the highest cost:

  • DECram device

  • Directly connected device in the same physical location

  • Directly connected device in a remote location

  • DECram served device

  • Default value for other served devices

The value supplied by the /READ_COST qualifier overrides the default assignment. The shadowing driver adds the value of the current queue depth of the shadow set member to the READ_COST value and then reads from the member with the lowest value.

Different systems in the cluster can assign different costs to each shadow set member.

When you specify a shadow set (DSAn) instead of a shadow set member, the read cost setting for all shadow set members reverts to the default read cost settings established automatically by the shadowing software. The specified shadow set must be mounted on the system where the command is issued. You an specify any value for the cost; the value is ignored, and the setting reverts to the default settings.

After you have applied this qualifier to a member, the setting remains in effect as long as the member is part of the shadow set. If the member is removed from the shadow set and later returned, this qualifier must be specified again.

If the /SITE command qualifier has been specified, the shadowing driver takes site values into account when it assigns default READ_COST values. In order for the shadowing software to determine whether a device is in the category of “directly connected device in a remote location,” the /SITE command qualifier must have been applied to both the shadow set and the shadow set member.

Reads requested for a shadow set from a system at site 1 are performed from a shadow set member that is also at site 1. Reads requested for the same shadow set from site 2 can read from the member located at site 2.

NOTE: DECram can shadow a DECram disk to a physical disk. However, be aware that in the current implementation of Volume Shadowing for OpenVMS, if the physical disk goes away, you are writing to a volatile disk.

/RESET_COUNTERS

Resets the shadowing-specific counters that are maintained for each shadow set. Counters that are reset to zero (0) are:

  • HBMM Reset Count

  • Copy Hotblocks

  • Copy Collisions

  • SCP Merge Repair Count

  • APP Merge Repair Count

You can display the current settings of the counters using the SHOW SHADOW command. The HBMM Reset Count refers to the number of times the RESET_THRESHOLD value is met. The RESET_THRESHOLD is the setting that determines how frequently a bitmap is cleared. Using the HBMM Reset counter, you can gauge the rate of threshold resets.

/RECOVERY_

OPTIONS=DELAY_

PER_SERVED_

MEMBER=n

Allows the system manager to adjust the rating assigned to a system based on a delay assessed for each MSCP served shadow set member on that system. The value specified by this qualifier overrides the value established by the SHADOW_PSM_RDLY system parameter. The default delay for each MSCP served member is 30 seconds and the valid range for the specified delay is 0 through 65,535 seconds. When a copy or merge operation is needed on a shadow set that is mounted on multiple systems, OpenVMS Volume Shadowing attempts to perform this work on a system that has a local connection to all of the shadow set members. Systems are rated with a penalty (delay time) assessed for each shadow set member that is MSCP served to the system. No delay is added for local members, so a system with all locally accessible shadow set members is likely to perform the work before a system where one or more members is served. IF /ALL is also specified, the specified delay is applied to all currently mounted shadow sets. See TBS for more information.

/SITE = n {ddcu:| DSAn:}

Indicates to the shadowing driver the site location of the specified shadow set (DSAn:) or shadow set member (ddcu:).

The SHADOW_SITE_ID system parameter defines the default site location of the shadow set. You can override the default location of the shadow set with this qualifier.

The valid range for the site location, represented by n, is 1 through 255.

If /ALL is specified, all shadow sets are assigned the new value. The shadow set’s member site values remain unchanged.

After you apply this qualifier, the setting remains in effect until you change it using a SET SHADOW/SITE command.

This qualifier can improve read performance because the member that is physically local to the system is the preferred disk from which to read, provided that you specify the /SITE qualifier for each shadow set member and for the shadow set. (In a Fibre Channel configuration, shadow set members at different sites are directly attached to the system. For the Volume Shadowing and OpenVMS Cluster software, there is no distinction between local and remote in multiple-site Fibre Channel configurations.)

/STALL=WRITES[=nnn]

Pauses the write operations for nnn seconds. The default time is SHADOW_MBR_TMO. If a value is not specified for nnn, the lock on write operations is released after SHADOW_MBR_TMO seconds. For example:

SET SHADOW DSA42 /STALL=WRITES

In this example, the writes are stalled to the shadow set for a period of SHADOW_MBR_TMO seconds.

SET SHADOW DSA42 /STALL=WRITES=60

In this example, the writes are stalled to the shadow set for a period of 60 seconds.

/NOSTALL=WRITES[=nnn]

Releases the lock on write operations after the specified period (nnn seconds). After the specified period is over, writes are allowed to the shadow set members. See the following example:

SET SHADOW DSA42 /STALL=WRITES=60

SET SHADOW DSA42 /NOSTALL=WRITES=30

In this example, initially the write operations are locked for a period of 60 seconds. On providing the /NOSTALL qualifier, the writes are allowed to the shadow set after a period of 30 seconds.

 

Using /DEMAND_MERGE to Start a Merge Operation

The /DEMAND_MERGE qualifier was created to force a merge operation on shadow sets that were created with the INITIALIZE/SHADOW command without specifying the /ERASE qualifier. The /DEMAND_MERGE qualifier ensures that all blocks not in use by active files are the same. The system manager can enter this command at a convenient time. If the /ERASE qualifier was not used when the shadow set was created with /INITIALIZE/SHADOW, and the SET SHADOW/DEMAND_MERGE command has not been executed, then the higher overhead of a full merge operation on this shadow set is encountered after a system failure.

System managers can also use the SET SHADOW/DEMAND_ MERGE command if the ANALYZE/DISK/SHADOW command found differences between the members of the shadow set (see “Using ANALYZE/DISK/SHADOW to Examine a Shadow Set”).

SHOW SHADOW Management Functions

The SHOW SHADOW command reports on the status of the specified shadow set and indicates whether a merge or copy operation is required, depending on the qualifier that you specify. If a merge or copy operation is required, this command reports whether it is pending or in progress. The qualifiers are described in this section. To use this command, specify the shadow set’s virtual unit name, followed by the qualifiers you want to use, as shown in the following example:

$ SHOW SHADOW DSAnnnn:/qualifier/qualifier/

/ACTIVE

This qualifier returns one of three possible states:

  • Merge or copy is not required

  • Copy is in progress on node nnnnx at LBN xxxx

  • Merge is in progress on node nnnnx

/COPY

This qualifier returns one of three possible states:

  • Copy is not required

  • Copy is pending

  • Copy is in progress on node nnnnx at LBN xxxx

/MERGE

This qualifier returns one of three possible states:

  • Merge is not required

  • Merge is pending

  • Merge is in progress on node nnnnx at LBN xxxx

/OUTPUT=file-name

This qualifier outputs any messages to the specified file.

Example 4-8 shows sample output from the SHOW SHADOW command:

Example 4-8 SHOW SHADOW Sample Output

$SHOW SHADOW DSA716: 

_DSA716: TST716
  Virtual Unit SCB Status: 0001 - normal
  Local Virtual Unit Status: 00000010 - Local Read

  Total Devices         2       VU_UCB          810419C0
  Source Members        2       SCB LBN         000009C8
  Act Copy Target       0       Generation      00A15F90
  Act Merge Target      0       Number          EDA9D786
  Last Read Index       0       VU Site Value          5
  Master Mbr Index      0       VU Timeout Value    3600
  Copy Hotblocks        0       Copy Collisions        0
  SCP Merge Repair Cnt  0       APP Merge Repair Cnt   0


  Device $252$DUA716            Master Member
  Index 0 Status  000000A0      src,valid
  Ext. Member Status    00
  Read Cost             42      Site 5
  Member Timeout        120     UCB  8116FF80

  Device $252$DUA1010
  Index 1 Status  000000A0      src,valid
  Ext. Member Status    00
  Read Cost             500     Site 3
  Member Timeout        120     UCB  811DD500


Managing Shadow Sets With SET SHADOW (Integrity servers and Alpha)
  		 


Prioritizing Merge and Copy Operations