HP 3000 Manuals

STORE and TurboSTORE/iX Products Manual

Preparing Tape and DDS Devices 

Prepare your backup devices by mounting the first media in the stack near
each device onto that device.  Follow the instructions in Chapter 3,
"Preparing Storage Devices," for mounting backup media.

After mounting the media, check the console for a message telling you
that the volume has been mounted.  For example:

     14:47/31/VOL (Unlabeled) mounted on LDEV#8

Note the backup drive's logical device (LDEV) number.  (The LDEV number
is 8 in the example above.)  You may need it to answer a backup request
later.

Single Tape Devices 

When you store to a single backup device, STORE only writes files to one
device at a time.  When the backup media is full, it automatically
rewinds then prompts you to load new backup media.  When the second unit
of backup media is loaded, STORE continues writing files until all of the
qualified files are stored or another unit of backup media is needed.  If
you are storing many files, or files that are particularly large, you may
need individually load several units of backup media onto the single
device.

Figure 3-7  illustrates a single-device backup.


          Figure 3-7.  Single-Device Backup 

The FILE command assigns a filename to a backup device according to its
logical device number or its device class.  For example, the FILE command
below assigns the filename T to the device with LDEV 8:

     :FILE T;DEV=8 

To store files to only one device, backreference that device in your
STORE command.  For example:

     :FILE T;DEV=TAPE 

     :STORE @.OPERATOR.SYS;*T 

Using one or more FILE commands is recommended, especially when your
system is configured to automatically allocate devices (autoreply) or
when you are using multiple backup devices.


NOTE  If auto reply is not enabled on the backup device designated, a
      reply from the console is necessary to allocate that device for a
      STORE process.  See Chapter 8, "Handling Media Requests," for more
      information.

      If you are using labeled tapes for your backup, you may or may not
      have to respond to console requests, depending on how your system
      is configured.  Refer to the "Storing to Labeled Tapes" section in
      Chapter 5 for more information on using labeled tapes.


The FILE command below assigns the filename BACKUP to the device with the
device class name TAPE.

     :FILE BACKUP;DEV=TAPE 

Using the backup device's logical device number is a more exact way to
assign a filename to a particular device.  There is only one device
defined as LDEV 8 on your system.  However, several devices may be
assigned the device class TAPE. When you use device classes to name
backup devices, STORE asks you to assign a logical device number to each
filename with a backup request.

FILE Commands for Automatically Allocated Devices.   

In order to have devices automatically allocated to the backup, you must
assign a different filename for each backup device allocated; use an LDEV
number or a unique device class for each FILE command you use, one for
each device.

Refer to Chapter 8, "Handling Media Requests," for a description of
automatically allocated devices.

Multiple Tape Devices 

All STORE and TurboSTORE products allow the use of multiple devices for
backup.  Multiple devices are identified as a pool of available devices.
When you store to multiple devices, the devices must have similar
characteristics; different device types are not allowed.  The device
characteristics that must be identical are:

   *   Devices must be all local or all remote.

   *   All devices must have the same density.

   *   All devices must have the same record size.

   *   All backups must be either labeled or unlabeled; there cannot be a
       mix.

   *   Different types of backup devices cannot be used together in one
       backup.  A backup must be performed with only one type of backup
       device at a time.  Note that different models of DDS drives (i.e.,
       SCSI or HPIB) can be mixed.  Different models of magnetic tape
       drives (7980, 7980XC, etc.)  can also be used together.

Multiple devices can be used as:

   *   Sequential devices.

   *   Parallel devices.

   *   Parallel device pools.

Using Tape Devices Sequentially.   

With sequential backup devices, when the first backup on the first backup
device is filled, it immediately begins writing files to a second backup
on the second backup device and the first backup rewinds.  When the first
backup is rewound, you can unload it and prepare the drive with a new
backup.  You do not lose time while the first backup is rewinding nor
while you are loading a new backup.

When the backup on the last sequential device is filled, the process
returns to the first device.  It continues cycling through all the
devices in the device pool until all of the specified files are stored.

The maximum number of serial magnetic tape or DDS devices allowed is 8.
However, you generally do not need to use more than two devices in
serial.  You get better backup performance if you use multiple devices in
parallel.  However, using two devices in serial can be useful for some
unattended backup functions.  For example, if your backup usually fits on
one media, then using two devices in serial allows your backup to finish
unattended, even if your data grows and one night overflows one piece of
media.

Serial devices can also help a backup to continue unattended in the event
of a media write error.  If STORE encounters an error writing to a backup
media, it marks the current media bad and unloads it.  It then rewrites
the backup data to the next mounted serial device, and the backup
continues uninterrupted.  This gives you enough time to mount another
media on the other drive, if needed.

Figure 3-8  illustrates a sequential device backup.


          Figure 3-8.  Sequential Backup 

Use the FILE command to give each device a filename that reminds you of
its position.  Then use the STORESET parameter in a STORE command to
reference the multiple devices.  For example, to store files to three
sequential devices, use the following set of commands: 

     :FILE SEQ1;DEV=7 
     :FILE SEQ2;DEV=8 
     :FILE SEQ3;DEV=9 
     :STORE @.@.@;;STORESET=(*SEQ1,*SEQ2,*SEQ3) 

The above STORE command copies all system and user files to three
sequential devices.  The parentheses surrounding backreferenced filenames
group the devices into a device pool. 


NOTE  You do not backreference the filename of a backup device
      immediately after the name(s) of the file(s) you are storing when
      you use the STORESET parameter.  Instead, you must use a
      placeholder for the missing parameter normally supplied when using
      a single backup device.  The placeholder is provided by the use of
      ";;" in the STORE command.


If you gave the backup devices a single filename such as:

     :FILE T;DEV=TAPE 

enter the following STORE command to copy files to a set of three
sequential backup devices:

     :STORE @.@.@;;STORESET=(*T,*T,*T) 


NOTE  Only unlabeled media can be used for a sequential device backup.  A
      maximum of 8 devices can be specified in each serial device pool.


Using Tape Devices in Parallel.   

With parallel devices, you have the capability of reducing backup time by
storing different files on different devices at the same time.  When you
store files to a set of parallel devices, the files are grouped before
the store begins and then copied to multiple devices simultaneously.  For
example, when you have three parallel devices, your files are partitioned
into three subsets.  Files in the first subset are copied to the first
backup drive, the files in the second subset are copied to the second
backup drive, and so on.

When a piece of media is filled, you are prompted to mount the next piece
of media on that device.

Depending upon the characteristics of your files and your backup devices,
storing files to parallel devices usually saves more time than using
sequential devices.

Figure 3-9  illustrates a parallel device backup.


          Figure 3-9.  Parallel Backup 

Currently, all STORE and TurboSTORE products support a maximum of 16
parallel backup devices.  The actual speed of performance depends on the
system, disk configuration and the backup devices used.

When using a multiple-processor machine, you can see increased backup
performance when doing parallel backups.  Each parallel device or device
pool is controlled by a separate process.  Since each process can be run
simultaneously on different processors, this will improve your backup
performance.

A general rule for doing multi-processor parallel backups is to use one
less parallel set than you have processors.  For example, on a 4-way
system, perform a 3-device parallel backup.  This is recommended because
STORE uses two additional processes to control the overall backup.


NOTE  Depending on your system configuration and bandwidth, you should
      still see increased backup performance using parallel devices, even
      if you use more parallel devices than you have processors.


To store files to a set of four parallel devices, the following set of
commands can be used:

     :FILE PARA;DEV=7 
     :FILE PARB;DEV=8 
     :FILE PARC;DEV=9 
     :FILE PARD;DEV=11 
     :STORE @.OPERATOR.SYS;;& 
     :STORESET=(*PARA),(*PARB),(*PARC),(*PARD) 

If you gave the backup devices a single filename such as:

     :FILE T;DEV=TAPE 

enter the following STORE command to copy files to a set of four parallel
backup devices:

     :STORE @.@.@;;STORESET=(*T),(*T),(*T),(*T) 

Describe parallel devices in the STORESET parameter by enclosing each
backreferenced device filename within parentheses.  Use commas to
separate devices.

Using Parallel Device Pools.   

Parallel device pools are multiple sets of sequential devices used in
parallel.  Using parallel device pools is often the most efficient way to
store a large set of files when you have several backup devices.
Parallel device pools give you the advantages of both parallel and
sequential devices.  You copy file subsets to different devices
simultaneously, and can have another sequential device ready when the
media is filled in any device pool.

Figure 3-10  illustrates a parallel device pool backup.


          Figure 3-10.  Parallel Device Pools 

Up to eight serial backup devices are currently supported within a
parallel device pool.  Maximum performance is obtained by using three or
four parallel sets, each consisting of two sequential devices.

To store files to parallel device pools, use parentheses to group the
devices into pools.  Separate the devices in the pool from one another
with commas.  Commas also separate each device pool.  For example, the
following commands copy files to two parallel device pools.  Each device
pool contains two sequential devices.  In the following example, STORE
uses a total of four devices divided into two device pools.

     :FILE PPA1;DEV=7 
     :FILE PPA2;DEV=8 
     :FILE PPB1;DEV=9 
     :FILE PPB2;DEV=11 
     :STORE @.OPERATOR.SYS;;STORESET=(*PPA1,*PPA2),(*PPB1,*PPB2) 

If you gave the backup devices a single filename such as:

     :FILE T;DEV=TAPE 

enter the following STORE command to copy files to a set of parallel
device pools:

     :STORE @.@.@;;STORESET=(*T,*T),(*T,*T) 

Using $NULL as a STORE Device 

The devices specified for a backup can also refer to $NULL. This
essentially does the backup to the "bit bucket"--no data is stored to any
backup media.  This type of backup can be done by specifying a file
equation prior to performing the backup.  .  Instead of specifying a tape
device, specify $NULL. For example:

     FILE N=$NULL

Doing so causes STORE to use $NULL as its output device.  The command
line is parsed, the input fileset scanned, all files are read from disk,
and all output is displayed as normal.  The only real difference is that
the data is not actually being written to an output device.

This feature can be useful when trying to determine which files will be
stored by STORE, as a trial run.  It can also be used, with EXTREME
caution, with the ;PURGE option, to remove all specified files.

When using this feature, keep in mind that your files are NOT being
stored to any device, so the data has not been saved anywhere.

Using Remote Devices for Backups 

STORE and TurboSTORE now support remote backup devices for storing and
restoring files.  This feature, which was previously only available using
CMSTORE, allows you to specify a backup device, or devices, on a remote
system for your backups.  A connection to the remote system must exist
before the STORE is invoked.  Once the remote connection is established,
a file equation should be created to point to the remote device.  For
example, to store to a tape drive on the remote system BROWNY, issue the
following FILE command:

     FILE REMOTE;DEV=BROWNY#TAPE

This file equation can then be used as the device file argument to STORE,
RESTORE, or VSTORE, or can be used with the STORESET or RESTORESET
options.  For example, using the file equation defined above, the
following STORE command will back up files to a remote tape drive on
BROWNY:

     STORE @.@.@;*REMOTE;SHOW

Although the initial console device request will appear on the console of
the remote system, all further STORE console messages will be sent to the
local system's console.  These messages will also be sent to the backup's
$STDLIST.


NOTE  Remote backup is currently only supported for unlabeled backups.
      Labeled backups cannot be accessed remotely by either STORE or
      CMSTORE.

      Also, magneto-optical devices cannot be used remotely.  Any backups
      to MO devices must be done to a local device.

MPE/iX 5.5 Documentation