Simultaneous operation of two tape drives -- possible?
Percival P. Cassidy
up, and I want all my backups to run at night when the computers would
not otherwise be in use, I got the bright idea of buying a second
Sony/Compaq/Dell DDS4 autoloader ($50 on eBay) and having both operating
concurrently on the same machine running BackAgain/2K Server ver. 4.1,
backing up different volumes or different machines across the Gigabit
network.
The first instance of BA2K runs OK, but the second instance generates
nothing but errors. Is this likely to be limitation of the software, or
is it a limitation of the SCSI bus, or...?
The two drives have different SCSI IDs and operate just fine one at a
time, but I don't see a way of using two drives at the same time other
than by, if possible, running two instance of the program.
If push comes to shove, of course, I could hook each drive up to a
different computer, but I was hoping to avoid that.
Any suggestions?
Perce
Joe Negron
I had a similar issue some time back. You must start a separate
instance of the program.
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Joe Negron from Bensonhurst, Brooklyn, NY, USA
Percival P. Cassidy
> On 2009-04-11, Percival P. Cassidy<nob...@notmyISP.invalid> wrote:
>> Since I am accumulating an ever-increasing amount of stuff to be backed
>> up, and I want all my backups to run at night when the computers would
>> not otherwise be in use, I got the bright idea of buying a second
>> Sony/Compaq/Dell DDS4 autoloader ($50 on eBay) and having both operating
>> concurrently on the same machine running BackAgain/2K Server ver. 4.1,
>> backing up different volumes or different machines across the Gigabit
>> network.
>>
>> The first instance of BA2K runs OK, but the second instance generates
>> nothing but errors. Is this likely to be limitation of the software, or
>> is it a limitation of the SCSI bus, or...?
>>
>> The two drives have different SCSI IDs and operate just fine one at a
>> time, but I don't see a way of using two drives at the same time other
>> than by, if possible, running two instance of the program.
>>
>> If push comes to shove, of course, I could hook each drive up to a
>> different computer, but I was hoping to avoid that.
>>
>> Any suggestions?
> I had a similar issue some time back. You must start a separate
> instance of the program.
And both instances did what they were supposed to do?
I did start a separate instance of the program, but the second one did
nothing but generate errors.
More detail: I actually run my backups from a batch file (including
REXX) that sets up name and date information for the Description of the
backup, then executes the cltape.exe program with appropriate
parameters. I was running two versions of the batch file, each with
different parameters to backup different drives to different tape drives.
Maybe I should try two instances of baii.exe and see if they will run
concurrently without misbehaving.
Perce
Bob Eager
<nob...@notmyISP.invalid> wrote:
Given the quality of that software (which I admit I use!) I would be
very wary of running multiple instances...
Joe Negron
> On 04/13/09 01:19 am Joe Negron wrote:
>
>>On 2009-04-11, Percival P. Cassidy<nob...@notmyISP.invalid> wrote:
>>>Since I am accumulating an ever-increasing amount of stuff to be backed
>>>up, and I want all my backups to run at night when the computers would
>>>not otherwise be in use, I got the bright idea of buying a second
>>>Sony/Compaq/Dell DDS4 autoloader ($50 on eBay) and having both operating
>>>concurrently on the same machine running BackAgain/2K Server ver. 4.1,
>>>backing up different volumes or different machines across the Gigabit
>>>network.
>>>
>>>The first instance of BA2K runs OK, but the second instance generates
>>>nothing but errors. Is this likely to be limitation of the software, or
>>>is it a limitation of the SCSI bus, or...?
>>>
>>>The two drives have different SCSI IDs and operate just fine one at a
>>>time, but I don't see a way of using two drives at the same time other
>>>than by, if possible, running two instance of the program.
>>>
>>>If push comes to shove, of course, I could hook each drive up to a
>>>different computer, but I was hoping to avoid that.
>>>
>>>Any suggestions?
>
>>I had a similar issue some time back. You must start a separate
>>instance of the program.
>
>And both instances did what they were supposed to do?
Yes. I was using BA2 4.0
>I did start a separate instance of the program, but the second one did
>nothing but generate errors.
>
>More detail: I actually run my backups from a batch file (including
>REXX) that sets up name and date information for the Description of the
>backup, then executes the cltape.exe program with appropriate
>parameters. I was running two versions of the batch file, each with
>different parameters to backup different drives to different tape drives.
>Maybe I should try two instances of baii.exe and see if they will run
>concurrently without misbehaving.
I didn't realize you were using the CLI version. I used the PM version.
The reply I got when I e-mailed CDS's tech support was that you had to
set the "Object Open Bevior" option to "Create New Window" in order to
ensure that the program used a different memory space or something. I'm
unsure of how you'd do that with the CLI version.
--
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Don't overestimate the decency of the human race.
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War is good for business - invest your son.
ECHO is OFF
James J. Weinkam
command prompt window and invoke the program again in that window and you have
two separate execution instances of the program running simultaneously, and
independently as far as the operating system is concerned.
If you invoke the program by double clicking on a program object, you can
configure the object to achieve the same effect by right clicking on it and
opening the properties notebook, going to the window tab and selecting "Create
new window" under "Object open behavior."
However this only solves part of your problem. For two concurrent instances of
the same program to run correctly, the program itself has to have been
designed to allow this behavior. For example, many programs use a permanent
database of some sort or create temporary files. If the program does not use
proper synchronization when consulting and updating its data base, or if it
uses hard coded names for its temporary files, an attempt to run multiple
invocations simultaneously will almost certainly come to grief even though the
operating system does everything right.
If such is the case, it still might be possible to salvage the situation. For
example, if the program a) keeps its database in the same directory as the
executable, or b) opens its temporary files in the current directory, or c)
looks for its database or places its temporaries in a path specified in an
environment variable, then you can: a) set up separate copies of the program
and its files in two (or more) directories, b) use different current
directories for the separate invocations (you will have to create two distinct
program objects with different "Working directories"), or c) set the
environment variable before invoking the program from the command line use a
command file to invoke the program that first sets the appropriate environment
variable and change the program object to invoke the command file rather than
the executable. Of course you will also have to ensure that the portions of
your system that the separate instances operate on are disjoint and you will
have to live with the fact that the program's data base id divided into
separate parts.
I have no idea how much if any of this applies to Back Again. You will have to
experiment a bit to discover the exact issues germane to that application.
Percival P. Cassidy
> Since I am accumulating an ever-increasing amount of stuff to be backed
> up, and I want all my backups to run at night when the computers would
> not otherwise be in use, I got the bright idea of buying a second
> Sony/Compaq/Dell DDS4 autoloader ($50 on eBay) and having both operating
> concurrently on the same machine running BackAgain/2K Server ver. 4.1,
> backing up different volumes or different machines across the Gigabit
> network.
>
> The first instance of BA2K runs OK, but the second instance generates
> nothing but errors. Is this likely to be limitation of the software, or
> is it a limitation of the SCSI bus, or...?
I discovered that the autoloader I just acquired is defective: it
misidentifies the kind of tape that is loaded -- e.g., a cleaning tape
as DDS1, and DDS3 and DDS4 tapes as illegal -- and was simply returning
the tape to the slot but not ejecting the magazine; I wasn't taking note
of the messages on the LCD.
Perce
Percival P. Cassidy
I now have yet another of these autoloaders -- sold "As is" for 10 bucks
and with an error message displaying on the LCD. It had a magazine in it
(I've paid a lot more than $10 for just a magazine) and a jammed tape --
probably was powered down while partway through a load or unload
operation. 20 minutes later I had another working autoloader.
BA2K does seem to be able to perform two backups simultaneously but
sometimes gets confused about which drive is which. E.g., I told it to
do a backup to the second drive and it loaded a tape from the magazine
in that drive, then started backing up to a tape that was already loaded
in the first drive.
Also, I notice that when I drag and drop a tape back to the magazine
using the device control notebook, sometimes the drive's LCD screen
displays "Move Medium ...," and it returns the tape to the magazine and
does nothing else; other times it will display "Unload Tape ..." and
load the next tape as well. Anybody seen this and have an explanation?
Perce
Percival P. Cassidy
>>>> Since I am accumulating an ever-increasing amount of stuff to be backed
>>>> up, and I want all my backups to run at night when the computers would
>>>> not otherwise be in use, I got the bright idea of buying a second
>>>> Sony/Compaq/Dell DDS4 autoloader ($50 on eBay) and having both operating
>>>> concurrently on the same machine running BackAgain/2K Server ver. 4.1,
>>>> backing up different volumes or different machines across the Gigabit
>>>> network.
>>>>
>>>> The first instance of BA2K runs OK, but the second instance generates
>>>> nothing but errors. Is this likely to be limitation of the software, or
>>>> is it a limitation of the SCSI bus, or...?
<snip>
>> I did start a separate instance of the program, but the second one did
>> nothing but generate errors.
As I mentioned in another message, the second drive was defective and I
have replaced it.
>> More detail: I actually run my backups from a batch file (including
>> REXX) that sets up name and date information for the Description of the
>> backup, then executes the cltape.exe program with appropriate
>> parameters. I was running two versions of the batch file, each with
>> different parameters to backup different drives to different tape drives.
>
>> Maybe I should try two instances of baii.exe and see if they will run
>> concurrently without misbehaving.
>
> I didn't realize you were using the CLI version. I used the PM version.
> The reply I got when I e-mailed CDS's tech support was that you had to
> set the "Object Open Bevior" option to "Create New Window" in order to
> ensure that the program used a different memory space or something. I'm
> unsure of how you'd do that with the CLI version.
Now that I have two tape drives that work OK, I have found that if I
have "detach clback ..." in the batch file (I mistyped previously when I
wrote 'cltape.exe') with command lines directing backups to different
drives, the two instances of the program seem to work just fine.
Perce