Prevents disk and file fragmentation on OpenVMS® systems
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CleanDisk was developed and is supported by Touch Technologies, Inc.
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The following are trademarks of Touch Technologies, Inc., and may be used only to describe products of Touch Technologies, Inc.:
DYNAMIC TAPE ACCELERATOR INTOUCH REMOTE TAPE FACILITY DYNAMIC LOAD BALANCER PLUS CleanDisk REMOTE DEVICE FACILITY
The following are trademarks of Digital Equipment Corporation, and may be used only to describe products of Digital Equipment Corporation:
DBMS DCL DECNET RDB RMS VAX VMS
Revised 16-Jul-1995
CleanDisk prevents disk and file fragmentation on OpenVMS systems. CleanDisk does this by intercepting file creation and file extension requests. The intercepted requests are modified to reduce fragmentation. CleanDisk is normally enabled system-wide, but can be disabled (and later re-enabled) for individual processes via DCL commands.
CleanDisk runs on OpenVMS 5.5 and later.
CleanDisk is written in a combination of MACRO-32, C and BLISS-32. This makes CleanDisk fast and efficient, and able to do its work using a minimum of CPU time.
The purpose of this manual is to provide:
This manual is intended for use by the system manager or other technical personnel.
IF YOU HAVE NO SYSTEM MANAGER OR YOU HAVE QUESTIONS ABOUT INSTALLING CLEANDISK, PLEASE CALL TOUCH TECHNOLOGIES, INC. AT:
(800) 525-2527 toll free within the U.S. and Canada.
(619) 566-3603 elsewhere
CleanDisk is a software product that prevents disk and file fragmentation. Preventing disk and file fragmentation speeds up file access by reducing window turns and split I/O transfers. CleanDisk works exceptionally well on files such as:
The OpenVMS file system was designed many years ago. Since that time, CPU speeds have increased by over 10,000%! However, during that same time, I/O speeds have only increased a modest 200%. This has caused most systems that were initially CPU bound to now become I/O bound.
Whenever OpenVMS deletes a file, the various fragments of that file are placed into the ACP extent cache. The purpose of the extent cache is to speed up file allocations. Later, when a file is extended (or initially allocated), OpenVMS first scans the extent cache to fulfill the extension request. Since the extent cache contains random pieces of previously deleted files---the newly extended file becomes very fragmented!
In the event that the ACP extent cache doesn't contain enough disk fragments to fulfill the extension request, the ACP bitmap cache is scanned. This cache also contains random pieces of disk space.
If the ACP bitmap cache also does not contain enough disk space to fulfill the extension request, the entire BITMAP.SYS is scanned. This scan starts wherever the previous scan left off. The effect of the BITMAP.SYS file scan is again---a very fragmented file.
CleanDisk intercepts file open, creation and extension requests. The parameters given in each request are examined. If OpenVMS system default values are given, and CleanDisk determines that the default values would cause the file to be fragmented, CleanDisk modifies the values. The values are modified by requesting contiguous best try file allocation, and by requesting an optimized file extension size. On a typical OpenVMS system, CleanDisk will intercept and optimize thousands of file create and extend requests per day!
Note
To measure the effects of CleanDisk, see Chapter 4,
CleanDisk consists of two major components, the CLNdriver and the CDCONTROL procedure. The CLNdriver intercepts file system (XQP) requests and modifies the requests in order to prevent fragmentation. The CDCONTROL procedure enables or disables CleanDisk on a per-process basis. The CDSERVER process watches for newly-created processes and enables CleanDisk for them.
The CDSTARTUP.COM procedure starts up CleanDisk. This procedure installs the CLNdriver and also starts up the CleanDisk process. The CLNdriver intercepts file system requests, modifies the requests to prevent fragmentation, and passes the requests on to the OpenVMS XQP handler.
Each time CleanDisk intercepts an XQP request, the request is examined. If needed, the request is modified to:
By default, CleanDisk is enabled for all processes. In some cases you may wish to enable or disable CleanDisk activity on a per-process basis.
The TTI_CD:CDCONTROL procedure enables or disables CleanDisk on a per-process basis.
For example, to disable CleanDisk for your process, the following command
would be used:
$ @TTI_CD:CDCONTROL DISABLE
CleanDisk can be installed on systems running OpenVMS 5.5 and greater.
Note
Before installing CleanDisk, make sure that you have read this manual COMPLETELY.
CleanDisk can be installed on any computer running under OpenVMS version 5.5 or greater. The following items are included with this installation package:
To install CleanDisk on your computer, you need to work from a DEC VT100 or compatible terminal. Follow the steps listed below and type the commands shown. The OpenVMS system is space conscious, so be sure to type the commands EXACTLY as shown.
In order to run CleanDisk, you must have its product authorization key registered and loaded. For example:
Product: CLEANDISK
PRODUCER: TTI
Username: SYSTEM
Password: (your system password)
$ CREATE/DIRECTORY SYS$SYSDEVICE:[TTI_CD]
Note
CleanDisk can be loaded into any directory on any disk ...e.g., $1$WORK:[CD]
$ SET DEFAULT SYS$SYSDEVICE:[TTI_CD]
$ DIRECTORY
No files found.
$ ALLOCATE MSA0:
$ MOUNT MSA0:/FOREIGN
Volume is write locked
CD mounted on _MSA0:
Note
MSA0 may have to be replaced with the appropriate magtape identifier for your system.
$ BACKUP/LOG MSA0:*.* *.*/NEW_VERSION
$ DISMOUNT MSA0:
$ DEALLOCATE MSA0:
The transfer takes about 2 minutes.
As CleanDisk is transferred to disk, you will see a list of the files being transferred.
$ @SYS$SYSDEVICE:[TTI_CD]CDSTARTUP
For OpenVMS 5.x, the system startup command file is SYS$MANAGER:SYSTARTUP_V5.COM. For OpenVMS 6.x, the system startup command file is SYS$MANAGER:SYSTARTUP_VMS.COM.
CleanDisk has now been installed on your system.
If you have licensed CleanDisk for more than one node, repeat this installation procedure for each licensed node.
If you have licensed CleanDisk for an entire cluster, you can install CleanDisk once on a cluster-accessable disk. However, you will still need to execute the CDSTARTUP procedure on each node.
Privileges
The CDCONTROL procedure uses the CDCONTROL image. In order to execute this image, you must have the following privileges: NETMBX, TMPMBX
CleanDisk can be ENABLED or DISABLED on a per-process basis. In addition, there is a SHOW command.
$ @TTI_CD:CDCONTROL ENABLE
$ @TTI_CD:CDCONTROL DISABLE
$ @TTI_CD:CDCONTROL SHOW
A successful ENABLE or DISABLE will display a message on the terminal indicating the success of the requested operation.
If you need to see if CleanDisk has been enabled for the current process, use the SHOW command:
Example 3-1 Using the SHOW Command
$ @TTI_CD:CDCONTROL SHOW CD - CleanDisk (2.0) - CDcontrol Procedure Copyright (c) 1995 Touch Technologies, Inc. CD is ENABLED for your process. ...Modified file allocation requests: 13
To display the effects of CleanDisk system-wide, use the SHOW/ALL option.
Example 3-2 Using the SHOW/ALL Command
$ @TTI_CD:CDCONTROL SHOW/ALL
CD - CleanDisk (2.0) - CDcontrol Procedure
Copyright (c) 1995 Touch Technologies, Inc.
Modified
Pid Process Name User Name CD status Requests
26400081 SWAPPER not enabled
26400086 CONFIGURE SYSTEM enabled 0
26400087 IPCACP SYSTEM enabled 0
26400089 ERRFMT SYSTEM enabled 102
2640008A CACHE_SERVER SYSTEM enabled 0
2640008B CLUSTER_SERVER SYSTEM enabled 0
26400098 --RTclient-- SYSTEM enabled 0
2640009B XXX_09B_2 SMITH enabled 213
Modified file requests since CD was started: 486 (92%)
The last line of the display shows the total number of file create and extend requests that CleanDisk has optimized since it was started on this node. In order to measure the impact of CleanDisk on your system, you can check the percentage of all requests that CleanDisk modified.
In the above example, 92% of the file create and extend requests were found to be nonoptimal! CleanDisk modified these nonoptimal requests, for a total of 486 modifications.
Without CleanDisk, these requests would have resulted in fragmented files, higher I/O overhead and poorer response times.
Note
The CleanDisk Benchmark procedure requires 3000 blocks of disk space on the disk pointed to by SYS$SCRATCH. When the benchmark has completed, the disk space can be reclaimed.
Included with your CleanDisk kit, is a Benchmark procedure. By using the supplied procedure, you can measure the effectiveness of CleanDisk on your system. Also, the CDCONTROL SHOW/ALL command can be used to show the effects of CleanDisk system-wide (see Section 3.2.1,
The supplied Benchmark procedure performs the following tasks:
Benchmark symbols are used to perform specific steps in the benchmarking procedure.
| Symbol | Description | Argument |
|---|---|---|
| CRFILE | Creates an empty temporary file | none |
| EXFILE | Extends the temporary file by a number of blocks | Number of blocks to extend by |
| FRAGS | Displays file fragments | filename---defaults to the last temporary file created or extended |
When you use the Benchmark procedure, you will:
You can start the benchmark process by running the set up routine. The Benchmark set up routine is executed by entering the following command:
$ @TTI_CD:CD_BENCHSET
After executing the Benchmark set up routine, you can create a file and extend it several times. Then, you can see how many fragments the file contains by running the FRAGS report. Each retrieval pointer in the FRAGS report represents one fragment.
These are the symbols you will enter to create and extend a file several times and run the FRAGS report:
The following example shows the results of a benchmark run.
Example 4-1 Creating and Extending without CleanDisk Enabled
$ @tti_cd:cd_benchset
**********************************************
** CD Benchmark environment being set up...
Benchmark cleanup done
CleanDisk DISABLED
Fragmenting SYS$SCRATCH: by creating/deleting files
creating the temporary files...
deleting half of the temporary files...
$ crfile == "@tti_cd:cd_do crfile "
$ exfile == "@tti_cd:cd_do exfile "
$ frags == "@tti_cd:cd_do frags "
** CD benchmark environment set up completed.
**********************************************
$
$ crfile
sys$scratch:tti_cd999.tmp created
$ exfile 100
Extending sys$scratch:tti_cd999.tmp by 100 blocks
sys$scratch:tti_cd999.tmp extended
$
$ exfile 100
Extending sys$scratch:tti_cd999.tmp by 100 blocks
sys$scratch:tti_cd999.tmp extended
$
$ exfile 100
Extending sys$scratch:tti_cd999.tmp by 100 blocks
sys$scratch:tti_cd999.tmp extended
$
$ exfile 100
Extending sys$scratch:tti_cd999.tmp by 100 blocks
sys$scratch:tti_cd999.tmp extended
$
$ exfile 100
Extending sys$scratch:tti_cd999.tmp by 100 blocks
sys$scratch:tti_cd999.tmp extended
$
$ frags
File name: TTI_CD999.TMP;1
Retrieval pointers
Count: 3 LBN: 411
Count: 6 LBN: 18294
Count: 3 LBN: 48459
Count: 3 LBN: 83100
Count: 3 LBN: 89787
.
.
.
Count: 3 LBN: 938211
Count: 6 LBN: 945297
Count: 6 LBN: 972132
Count: 90 LBN: 1027965
Count: 51 LBN: 1028226
$
You can now enable CleanDisk using the command:
$ @TTI_CD:CDCONTROL ENABLE
Then, create another file, extend it several times and run the FRAGS report to see how many fragments the file contains. You can use the following symbols:
The following example shows the results of a benchmark run with CleanDisk enabled.
Example 4-2 Creating and Extending with CleanDisk Enabled
$ @tti_cd:CDCONTROL enable
CD - CleanDisk (Version 2.0) - Control Procedure
Copyright (c) 1995 Touch Technologies, Inc.
CleanDisk ENABLED
$ crfile
sys$scratch:tti_cd998.tmp created
$ exfile 100
Extending sys$scratch:tti_cd998.tmp by 100 blocks
sys$scratch:tti_cd998.tmp extended
$
$ exfile 100
Extending sys$scratch:tti_cd998.tmp by 100 blocks
sys$scratch:tti_cd998.tmp extended
$
$ exfile 100
Extending sys$scratch:tti_cd998.tmp by 100 blocks
sys$scratch:tti_cd998.tmp extended
$
$ exfile 100
Extending sys$scratch:tti_cd998.tmp by 100 blocks
sys$scratch:tti_cd998.tmp extended
$
$ exfile 100
Extending sys$scratch:tti_cd998.tmp by 100 blocks
sys$scratch:tti_cd998.tmp extended
$
$ frags
File name: TTI_CD998.TMP;1
Retrieval pointers
Count: 90 LBN: 1033836
Count: 102 LBN: 1033929
Count: 309 LBN: 1034061
$
You will notice that with CleanDisk enabled, the created and extended file contains far fewer fragments than the file created without using CleanDisk. Fewer fragments means fewer I/Os and fewer window-turns. In most cases, CleanDisk prevents 90 percent or more of file fragmentation. The reduced fragmentation, in turn, reduces file I/Os.
Note
If you do not see the results shown in this benchmark example, please contact our Technical Support staff for assistance. (The phone number is located in the preface of this manual.)
When you have finished benchmarking CleanDisk, the temporary files created by the benchmark can be deleted by entering the command:
$ @TTI_CD:CD_DO CLEANUP