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* *
* This is an update to an existing patch... *
* *
* Online links can be found at *
* http://ftp.support.compaq.com/patches/public/vms/axp/v7.2-1h1/dec-axpvms-vms721h1_rms-v0300--4.README
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TITLE: OpenVMS VMS721H1_RMS-V0300 Alpha V7.2-1H1 RMS ECO Summary

New Kit Date : 12-MAR-2001
Modification Date: Not Applicable
Modification Type: Updated Kit Supersedes VMS721H1_RMS-V0200
 
NOTE: An OpenVMS saveset or PCSI installation file is stored
       on the Internet in a self-expanding compressed file.
 
       For OpenVMS savesets, the name of the compressed saveset
       file will be kit_name.a-dcx_vaxexe for OpenVMS VAX or
       kit_name.a-dcx_axpexe for OpenVMS Alpha. Once the OpenVMS
       saveset is copied to your system, expand the compressed
       saveset by typing RUN kitname.dcx_vaxexe or kitname.dcx_alpexe.
 
       For PCSI files, once the PCSI file is copied to your system,
       rename the PCSI file to kitname-dcx_axpexe.pcsi, then it can
       be expanded by typing RUN kitname-dcx_axpexe.pcsi. The resultant
       file will be the PCSI installation file which can be used to install
       the ECO.
 

Copyright (c) Compaq Computer Corporation 2001. All rights reserved.

OP/SYS: OpenVMS Alpha

COMPONENT: RMS

SOURCE: Compaq Computer Corporation

ECO INFORMATION:

     ECO Kit Name: VMS721H1_RMS-V0300
                    DEC-AXPVMS-VMS721H1_RMS-V0300--4.PCSI
     ECO Kits Superseded by This ECO Kit: VMS721H1_RMS-V0200
     ECO Kit Approximate Size: 3120 Blocks
     Kit Applies To: OpenVMS Alpha V7.2-1H1
     System/Cluster Reboot Necessary: Yes
     Rolling Re-boot Supported: Yes
     Installation Rating: INSTALL_1
                           1 - To be installed on all systems running
                               the listed version(s) of OpenVMS.

     Kit Dependencies:

       The following remedial kit(s) must be installed BEFORE
       installation of this kit:

         VMS721H1_UPDATE-V0300
         VMS721H1_CLIUTL-V0100
                      
       In order to receive all the corrections listed in this
       kit, the following remedial kits should also be installed:

         None

ECO KIT SUMMARY:

An ECO kit exists for RMS on OpenVMS Alpha V7.2-1H1. This kit addresses
the following problems:

PROBLEMS ADDRESSED IN VMS721H1_RMS-V0300 KIT

  o Fix to prevent a fatal INVEXCEPTN lock manager bugcheck when
     global buffers are enabled.

     This problem involves a race condition with the following rare
     set of conditions occurring simultaneously:

         o The last accessor of a global section cleaning up any
            cached global bucket system locks on one node.

         o A lock request on another node resulting in delivery of a
            system fork lock blocking interrupt to the latter node
            that attempts to convert a lock after it has been dequeued
            by the last accessor.

            Images Affected: [SYS$LDR]RMS.EXE

  o Fix for invalid input parameter in call to SCH$QAST to prevent
     a potential fatal INVEXCEPTN system bugcheck when global
     buffers are enabled.

           Images Affected: [SYS$LDR]RMS.EXE

  o Fix for potential RMS lock hang when global buffers are
     enabled.

     This problem involves a rare condition if the last accessor of
     the global section is interrupted by an abort rundown, which
     may lead to the need for the cleanup of the global section not
     being properly detected. This could result in the survival of
     the global section and a global bucket system lock after the
     last accessor is deleted.

     Since this problem requires the accessor that is aborted to
     also be the last accessor, it is more apt to occur with a file
     that accessors come and go -- with a file that is opened and
     closed frequently and may have only one accessor at a
     particular time (e.g. RIGHTSLIST.DAT) -- versus a file with
     global buffers enabled that typically has several concurrent
     accessors at all times until there is an application (or
     system) shutdown.

          Images Affected: [SYS$LDR]RMS.EXE

  o Fix to prevent a nonfatal RMS bugcheck (ENQDEQFAIL) when an
     enqueue request fails with a CVTUNGRANT status.

     The ENQDEQFAIL bugcheck may be reported when an RMS lock
     manager request to rearm the blocking AST associated with a
     directory cache fails with a CVTUNGRANT status.

     The process may either:

     1. Terminate (SYSGEN parameter BUGCHECKFATAL not enabled)
         with an RMSBUG; or

     2. Crash the system (BUGCHECKFATAL enabled) with a RMSBUG.
         The footprint of the crash will reflect an R2 register
         value of %XFFFFFFF4 (ENQDEQFAIL) with an R0 register value
         of %X0000213c (SYSTEM-F-CVTUNGRANT).

         Images Affected: [SYS$LDR]RMS.EXE

  o Fix for SQO error on CONVERT/NOSORT with collated key.

     Producing an indexed file with a collated key using the
     qualifier /NOSORT with the CONVERT may fail with the following
     error:

             %CONV-F-READERR, error reading <filename>
             -RMS-F-SQO, operation not sequential (SQO set)

         Images Affected: [SYSEXE]CONVERT.EXE
                           [SYSLIB]CONVSHR.EXE

  o RMS support for new qualifier /SHARE added to SET FILE, which
     is dependent on the VMS721H1_CLIUTL-V0100 kit being installed.

     The /SHARE qualifier allows you to enable or disable global
     buffers or statistics on a file currently being accessed by
     other users. Only new accessors of the file will acquire the
     new settings. This qualifier requires SYSPRV (system
     privilege).

     The /SHARE qualifier is only valid with the following
     qualifiers:

           /[NO]GLOBAL_BUFFER=count/SHARE
           /[NO]STATISTICS/SHARE

     If other qualifiers are needed, they must be entered in a
     separate SET FILE command.

     /[NO]GLOBAL_BUFFER=count/SHARE

     The /SHARE qualifier can be used to enable or disable global
     buffers on a file currently being accessed. However, any new
     global buffer settings will only be applied to new accessors
     of the file. And if a file is already opened with global
     buffers, any new number of global buffers will not take effect
     until the file is closed by all accessors of the file.

     /[NO]STATISTICS/SHARE

     The /SHARE qualifier can be used to enable or disable
     statistics on a file currently being accessed. However, only
     statistics of new accessors of the file will be measured.

     EXAMPLE:

     $ SET FILE/SHARE/GLOBAL_BUFFER=5000/STATISTICS INVENTORY.IDX

     This example sets 5000 global buffers on the INVENTORY.IDX
     file and enables statistics. Without the /SHARE qualifier, if
     the file was open when the SET FILE command was issued, the
     following error would be returned: SYSTEM-W-ACCONFLICT (file
     access conflict). The /SHARE qualifier allows the global
     buffers and statistics to be enabled on an open file.
     However, these settings only apply to new accessors of the
     file.

     Images Affected: [SYS$LDR]RMS.EXE
                      [SYSEXE]SET.EXE
                      [SYSLIB]DCLTABLES.EXE with modified SET.CLD

     The latter two images require the installation of the
     VMS721H1_CLIUTL-V0100 kit.

PROBLEMS ADDRESSED IN VMS721H1_RMS-V0200 KIT

  o Autoextend problem with shared write sequential file if global
     buffers enabled.

     When an autoextend occurs with a shared write sequential file
     with global buffers enabled, if both readers and writers are
     concurrently processing data at the end-of-file, a window
     exists for the readers when either an infinite process loop
     may occur or an inappropriate RMS-E-EOF or RMS-F-IRC error may
     be returned. The likelihood of either problem occurring
     increases significantly if the deferred-write (DFW) option is
     enabled or the sequential file does not have a generous
     initial allocation or extend quantity.

          Images Affected: [SYS$LDR]RMS.EXE

     This fix is included in the next release after OpenVMS Alpha
     V7.2-1H1.

  o Fix for remote file transfer performance degradation if UPI
      enabled.

      As a side-effect of a DAP/FAL change made to the Alpha Version
      7.2 family, the SQO (sequential only) option was
      inappropriately disabled in a record stream when the UPI (user
      provided interlock) option was enabled if RMS detected any
      form of write sharing. This resulted in reducing the
      performance of a remote file transfer that had the UPI option
      enabled due to the overhead of sending the file
      record-by-record rather than using the more efficient block
      mode transfer supported by the SQO option.

          Images Affected: [SYS$LDR]RMS.EXE

     This fix is included in the next release after OpenVMS Alpha
     V7.2-1H1.

Problems Addressed In VMS721H1_RMS-V0100:

  o A LDQ (load quad) instruction generated by the Bliss-64 compiler
     (default quadword alignment) may result in an attempt being made
     to read or write 4 bytes beyond the end of an RMS internal buffer
     which ends exactly on a page boundary with an adjacent inaccessible
     page.

     The process may either:

       1. Terminate (SYSGEN parameter BUGCHECKFATAL not enabled)
           with an access violation (ACCVIO); or

       2. Crash the system (BUGCHECKFATAL enabled) with a SSRVEXCEPT
           ACCVIO.

     There are too many variables (for example, bucket size, number
     of buffers, number of keys, record location) to predict in
     advance that a file is vulnerable to this problem. However,
     we do know that the right combination of conditions must be
     rare since the problem has been dormant for several releases.
     It was introduced with the conversion of several Bliss-32 RMS
     modules to Bliss-64 as part of the support for 64-bit addresses
     added to Alpha V7.0.

  o An unusual timing condition may cause an application to get
     incorrect data returned due to an interaction between caching
     and read record access. Global buffers must be enabled on the
     file, and there must be several processes trying to
     concurrently access a data bucket that has to be brought into
     the global cache (i.e., is not already in the global cache).

     This was uncovered doing internal stress testing with an SMP
     (8 CPU) system with caching enhancements for a future release.
     It was reproduced with very heavy contention to a data bucket
     with sequential read access being done. We have not been able
     to reproduce the problem without the speed of the caching
     enhancements. It is unknown whether this problem could occur
     in V7.2-1H1, but it is best to apply this update as a precaution.

  o The hashing interlock mechanism, which was implemented in
     V7.2, has been redesigned to eliminate the timer-based
     strategy that was used during periods of high contention. A
     system could become overburdened by Timer Queue activity (IPL
     8) when the contention for an interlock reached a threshold.
     This Timer Queue activity precluded the interlock owner from
     releasing the interlock and resulted in excessive Timer Queue
     activity consuming the primary CPU.

       Images Affected:
         - [SYS$LDR]RMS.EXE
         - [SYS$LDR]DDIF$RMS_EXTENSION.EXE
         - [SYSLIB]SDARMS$SHARE.EXE

  o Fix to prevent a process hang waiting on an RMS lock when
     reverse (key-less-than) search criterion is used on a file

     with global buffers enabled.

     Access to an RMS indexed file may hang indefinitely waiting on
     a lock request when the following three conditions are met:

       - Global buffers are enabled.

       - Key-Less-Than match criterion is being utilized.

       - The key of reference is switched between two adjacent
          lookups (e.g., key of reference is switched from key 0 to
          key 1).

     This problem is fixed in the release of OpenVMS Alpha to
     follow V7.2-1H1.

  o This is a fix to prevent a SSRVEXCPT bugcheck during process
     rundown when an RMS AST is delivered to the process after the
     process address space has already been released. In order for
     this to occur, the process must have been utilizing global
     buffers. This issue represents a very small timing window and
     should be extremely rare.

  o Accessing a file by secondary key that has Recovery Unit (RU)
     journaling enabled in which a large number of deletes has
     occurred may incur an inordinate amount of direct IO activity.
     This is due to RMS having to process the RU deleted entries in
     the secondary key structure. This is not an issue when access
     to the file is by the primary key.

     This change is a performance enhancement in which RMS will now
     perform cleanup of the RU deleted Secondary Index Data Record
     entries when they are initially encountered through a read
     operation. This will reduce the IO required to process these
     entries for all future accesses. Access by the primary key of
     the file already performs this optimization.

  o CONVERT/SHARE previously read the input primary data records
     (record I/O) with the RAB$V_RRL (read regardless) option
     enabled. As a performance enhancement, RAB$V_RRL was replaced
     with the new RAB$V_NQL (no query locking) record option if
     /SHARE is used. This results in no record locking being done
     for all the reads of the primary data records from the input
     file.

  o The new Alpha global buffer read-mode lock support introduced
     in V7.2-1H1 is functionally compatible with both VAX and older
     Alpha releases. Operations in mixed clusters produce correct
     results. However, there is a locking fairness issue that may
     arise with mixed cluster operations (e.g., an Alpha V7.1-2 or
     V7.2-1 version or VAX versions).

     In a mixed cluster environment with very high contention for
     specific buckets, it is possible for accesses to write-shared
     files on nodes using read-mode bucket locking to dominate
     access to a bucket. Nodes without this support might be
     unable to access the bucket for a protracted period of time.

     While V7.2-1H1R does include the new global buffer read-mode
     lock support and so will not be affected by the latter issue,
     it is also possible to observe comparable behavior on all
     OpenVMS versions when dealing with accesses to write-shared
     files without global buffers enabled -- even on a standalone
     system. A similar fairness issue between lock conversions and
     new lock requests may be observed in which the new lock
     requests may remain ungranted for an extended period of time.

     This kit includes support in RMS for a new option to improve
     fairness under high contention conditions for write-shared
     files, but selecting this option may noticeably increase
     locking overhead. The option may be set at a process or
     system level. Since many applications will never encounter
     this issue, the default system behavior leaves this option
     disabled. A future lock management enhancement should make
     this fairness workaround unnecessary for later releases.

     The option is controlled using the /CONTENTION_POLICY qualifier
     to the DCL command SET RMS_DEFAULT. The following are valid
     PROCESS keywords (/SYSTEM not specified):

       NEVER Never use the higher overhead option
                      to improve fairness for any write-shared
                      files accessed by this process; minimal
                      overhead.

       SOMETIMES Use this option for fairer bucket
                      access (but higher overhead) to any
                      write-shared files with global buffers
                      enabled that are accessed by this
                      process.

       ALWAYS Use this option for fairer bucket
                      access (but higher overhead) to all
                      write-shared files accessed by this
                      process.
                            
       SYSTEM_DEFAULT (Default) Use system setting. Note
                       that this keyword is disallowed with
                       /SYSTEM.
                                 

     The following are valid SYSTEM keywords (/SYSTEM specified):

       NEVER (Default) Never use the higher
                      overhead option to improve fairness
                      for any write-shared files accessed
                      on the system; minimal overhead.

       SOMETIMES Use this option for fairer bucket
                      access (but higher overhead) to any
                      write-shared files with global
                      buffers enabled that are accessed
                      on the system.

       ALWAYS Use this option for fairer bucket
                     access (but higher overhead) to all
                     write-shared files accessed on the
                     system.

     In addition to the RMS image, modifications to the following
     images contained in the VMS721H1_UPDATE-V0300 kit (a prerequisite
     to installing this kit) are required in order for this
     functionality to take affect:

       - [SYSEXE]SET.EXE
       - [SYSMSG]CLIUTLMSG.EXE
       - replacement of revised SET.CLD in [SYSLIB]DCLTABLES.EXE

     Without these modified images, RMS will use NEVER as the
     default for the CONTENTION_POLICY option.

INSTALLATION NOTES:

This kit requires a system reboot. Compaq strongly recommends that
a reboot is performed immediately after kit installation to avoid
system instability

If you have other nodes in your OpenVMS cluster, they must also be
rebooted in order to make use of the new image(s). If it is not
possible or convenient to reboot the entire cluster at this time, a
rolling re-boot may be performed.

INSTALLATION INSTRUCTIONS:

Install this kit with the POLYCENTER Software installation utility
by logging into the SYSTEM account, and typing the following at the
DCL prompt:

PRODUCT INSTALL VMS721H1_RMS /SOURCE=[location of Kit]

The kit location may be a tape drive, CD, or a disk directory that
contains the kit.

Additional help on installing PCSI kits can be found by typing

    HELP PRODUCT INSTALL at the system prompt

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