Dynamic Tape Acceleratortm
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Appendix G
OpenVMS BACKUP Authorization Parameters

G.1 OpenVMS 5.2 BACKUP

The OpenVMS BACKUP utility was completely rewritten by Digital for OpenVMS 5.2. OpenVMS BACKUP 5.2 (and greater) offers increased performance. However, in order to realize performance gains, it is recommended that you provide a special username (e.g., BACKUP) when performing backup operations.

The following AUTHORIZATION parameters are recommended for the BACKUP username:

Table G-1 Minimum Recommended AUTHORIZATION Parameter Values
Parameter Minimum Value
BYTLM 128000
PGFLQUO 100000
WSQUOTA 16384
WSEXTENT 16384
DIOLM 4096
ASTLM 4096
ENQLM 1000
FILLM 127

Appendix H
Using Dynamic Tape Accelerator with Remote Device Facilitytm

Note
For detailed information on Remote Device Facility, see the Remote Device Facility reference manual.

Note

tm Remote Device Facility is a trademark of Touch Technologies, Inc.

H.1 ACCELERATING Remote Tape Devices

Note
Running RDF, DTA, and OpenVMS BACKUP at the same time requires a very fast CLIENT CPU. We recommend at least three VUPS.

Use of the DTA DATA COMPRESSION option requires at least 25 VUPs when using RDF, DTA, and OpenVMS BACKUP at the same time on a CLIENT node.

DTA data compression is not supported on Alpha systems at this time.

DTA can be used on an RDF CLIENT node to improve tape write performance and to monitor throughput rates to remote tape devices.

This is accomplished by:

  1. RDALLOCATING the remote tape device with RDF 


       $ @tti_rdev:rdallocate zeus::mub0: 
   RDF - VAX Remote Device Facility (Version 4.1) - RDallocate Procedure 
   Copyright (c) 1993, 1997 Touch Technologies, Inc. 
   Device ZEUS::ZEUS$MSA0 ALLOCATED, use TAPE01 to reference it

  2. ACCELERATING the tape device with DTA using the logical name that was assigned in the RDALLOCATE command. 


       $ @tti_dta:control accel tape01 1200

The ACCEL command takes the form: 


   $ @tti_dta:control accel device capacity

where device is the name of the RDALLOCATED tape device and capacity is the capacity of a single tape volume in megabytes.

The following command would be used to ACCELERATE a 4mm tape drive with a capacity of 1.2GB. 


   $ @tti_dta:control accel tape01 1200 
   Dynamic Tape Accelerator (V4.0) - Acceleration Procedure 
   Copyright (c) 1993, 1997 Touch Technologies, Inc. 
   TAPE01 accelerated

Note
Because the performance of most remote tape operations is limited by the network bandwidth, we suggest ACCELERATING the RDALLOCATED tape drive on only the CLIENT node.

H.2 DEACCELERATING an RDALLOCATED DEVICE

To deaccelerate a tape device, issue the following command: 


    $ @tti_dta:control deaccel device

Although the @TTI_DTA:CONTROL DEACCEL command can be used at any time, DTA delays the actual deacceleration until all pending I/O operations to the tape device have completed.

Note
An RDALLOCATED tape device should always be DEACCELERATED prior to RDDEALLOCATING the device. 


    $ @tti_rdev:rdallocate zeus::mub0: 
    $ @tti_dta:control accel tape01 1200 
        . 
        . various tape operations 
        . 
    $ @tti_dta:control deaccel tape01 
    $ @tti_rdev:rddeallocate tape01

H.3 PREACCELERATING an RDALLOCATED Device

If you would like to MONITOR an RDALLOCATED tape device but do not want to ACCELERATE it, you can use the PREACCEL command procedure. 


    $ @tti_dta:preaccel tape01 1200

H.4 The DTA Tape MONITOR

The DTA MONITOR procedure allows you to monitor the data transfer rate across the network to the physical tape device in KB/sec. The data transfer rate is determined from tape I/O acknowledgments sent by the RDSERVER node.

The flow of data from application to tape and resulting tape I/O acknowledgment is: 


                                    DATA 
             <-------<-----------<-----------<-----------<------- 
                             TAPE I/O ACKNOWLEDGMENT 
             -------->----------->----------->----------->-------> 
 
          +-----+     +--+                    +--+     +--+     +--+ 
          |     |     |  |                    |  |     |  |     |  | 
          |     |-----|  |---------//---------|  |-----|  |-----|  | 
          |     |     |  |                    |  |     |  |     |  | 
          +-----+     +--+                    +--+     +--+     +--+ 
 
           Tape        RDF       NETWORK       RDF      DTA      Application 
           Drive 
 
           RDSERVER NODE                         RDCLIENT NODE

To monitor a tape device, it must first be either ACCELERATED or PREACCELERATED. 


    $ @tti_rdev:rdallocate 
    $ @tti_dta:control accel tape01 1250 
    $ @tti_dta:monitor tape01

The DTA MONITOR can be viewed interactively or written to a file. To write the MONITOR to a file: 


    $ @tti_dta:monitor device file_spec

where device is the reference name of the RDALLOCATED tape device to monitor and file_spec is an OPTIONAL parameter indicating the logfile name. By default, the monitor displays on your terminal.

?30pc

Example H-1 DTA MONITOR Sample Display 


DTA MONITOR (4.0) of TAPE01:  on 12-JAN-1997 19:13:05.14  Sample 3 
User OPER, image BACKUP  SYS$SYSDEVICE:[TEST]MYFILE.LIS;12 
 
 
                               20      40      60      80     100 
                        + - - - + - - - + - - - + - - - + - - - + 
Percent of capacity    2|X 
Cachesize/100KB        8|XXXX 
 
                     500| 
                     450| 
                     400| 
Throughput History   350| 
    in KB/sec        300| 
                     250| 
                     200|   X X 
Average KB/sec: 180  150| X X X 
                     100| X X X 
                      50| X X X 
                       + - - - - - - - - - - - - - - - - - - - - 
 
I/O queue len :      96         Elapsed  :  12:53    Volume/Saveset: BACK02 
I/O requests  :     145         Func time:   0:02    Current Funct : WRITE 
Virtual KB/sec:     190         Est EOT  :   8:13    DTA state     : CACHING 
PHY/ACT KB/sec:     180/180     Errors   :      0    Device state  : OPEN 
PHY/ACT MB    :     14/15       HW cache :   NO      Compression   : ON

Appendix I
Answers to Commonly Asked Questions

The DTA startup procedure, dta_startup.com, fails with a no such device error. Why?

This error message can be caused by a bug in OpenVMS where SYSGEN does not properly set up a new device if there is a logical name on the system that is similar to the device name being set up in SYSGEN.

In the case of DTA, if there is a logical name that is similar to DT, DTA, or DTA0 that had been defined prior to the SYSGEN CONNECT statement in dta_startup.com, the start up procedure will fail with a no such device error.

DTA can be successfully started by temporarily deassigning the similar logical name or dta_startup.com can be placed ahead ahead of the procedure that defines the similar logical name in SYS$MANAGER:SYSTARTUP_V5.COM.

How can I find out what version of DTA is running?

To find out the DTA copyright date and current version of DTA, enter the following command at the $ prompt: 


        $ @tti_dta:dta_copyright 
 
        Dynamic Tape Accelerator (V4.0 ) -  Procedure 
        Copyright (c) 1989-1997 Touch Technologies, Inc.

Appendix J
User Notes

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