Hi,

Am just interested in the backup techniques that people use for DBISAM
tables.  Do you generally have to ensure no one is accessing DBISAM files
when backing them up?   If I wanted to backup tables prior to an important
process, would it work to open the files for exclusive use and back them up?
Would this be the best way?

Thankyou

Alex

Al


If you're up to date with DBISAM (ie V4) use its inbuilt backup otherwise my approach is to pick a key file (eg users) and open that exclusively so it essentially stops anyone else accessing the system.

If you don't get exclusive access then you might back up the .dat at one point, the .blb at another and the .idx at a third - no problem until you restore the data

Roy Lambert

Hi Roy,

Thanks for your response.  At the momen it is 3.30 DBISAM.  So just to
confirm, if I exclusively open a table, then I can safely copy that table?
Also, if I want to do a system-based backup, MUST make sure everyone is out
of the application?

Thanks

Alex

"Roy Lambert" <roy.lambert@skynet.co.uk> wrote in message
news:30F6A610-7DD3-4113-A081-AC9CC9F714EA@news.elevatesoft.com...
> Al
>
>
> If you're up to date with DBISAM (ie V4) use its inbuilt backup otherwise
> my approach is to pick a key file (eg users) and open that exclusively so
> it essentially stops anyone else accessing the system.
>
> If you don't get exclusive access then you might back up the .dat at one
> point, the .blb at another and the .idx at a third - no problem until you
> restore the data
>
> Roy Lambert
>

Al

>Thanks for your response. At the momen it is 3.30 DBISAM. So just to
>confirm, if I exclusively open a table, then I can safely copy that table?
>Also, if I want to do a system-based backup, MUST make sure everyone is out
>of the application?

That's exactly right.

Roy Lambert

"Al VAs" <deleteprefix_alex@favour.com.au> wrote in message
news:7CC09ECD-D05C-4F6E-A579-5A6E7F100B5A@news.elevatesoft.com...
> Hi Roy,
>
> Thanks for your response.  At the momen it is 3.30 DBISAM.  So just to
> confirm, if I exclusively open a table, then I can safely copy that table?

If it is a table that is kept open by the application, you can safely backup
the whole database. The fact that you were able to open it exclusively means
you are the only user. In fact, you could set up a dummy one record table
just for that purpose. Of course, you have to have a way to let a user know
that the table is not available, if someone tries to start the application
while you are doing the backup.

> Also, if I want to do a system-based backup, MUST make sure everyone is
> out of the application?
>

For sure. You are backing up files, not a logical database. You can't allow
any updates while you are doing the backup.

Robert

Hi Robert,

Thanks.  Just on that last point, how do those backup programs work, where
they are able to backup whilst files are active.  How does an airline
bookings database for example get backed up, where they have to remain
pretty much running 24/7?  Just out of interest.

Alex

"Robert" <ngsemail2005withoutthis@yahoo.com.ar> wrote in message
news:ADC69599-4EF5-42AC-A796-58B98D5F6243@news.elevatesoft.com...
>
> "Al VAs" <deleteprefix_alex@favour.com.au> wrote in message
> news:7CC09ECD-D05C-4F6E-A579-5A6E7F100B5A@news.elevatesoft.com...
>> Hi Roy,
>>
>> Thanks for your response.  At the momen it is 3.30 DBISAM.  So just to
>> confirm, if I exclusively open a table, then I can safely copy that
>> table?
>
> If it is a table that is kept open by the application, you can safely
> backup the whole database. The fact that you were able to open it
> exclusively means you are the only user. In fact, you could set up a dummy
> one record table just for that purpose. Of course, you have to have a way
> to let a user know that the table is not available, if someone tries to
> start the application while you are doing the backup.
>
>> Also, if I want to do a system-based backup, MUST make sure everyone is
>> out of the application?
>>
>
> For sure. You are backing up files, not a logical database. You can't
> allow any updates while you are doing the backup.
>
> Robert
>
>
>

Al,

> Thanks.  Just on that last point, how do those backup programs work, where
> they are able to backup whilst files are active.  How does an airline
> bookings database for example get backed up, where they have to remain
> pretty much running 24/7?  Just out of interest.

They run the backup inside a transaction. The degree to which this
impairs concurrency depends on whether the DB engine supports record
versioning or not.

Eryk

They may be using DBISAM v4.x .It allows you to backup while using the
database.


"Al VAs" <deleteprefix_alex@favour.com.au> wrote in message
news:F6257D4F-0203-4FAF-9544-51E5CC44D68A@news.elevatesoft.com...
> Hi Robert,
>
> Thanks.  Just on that last point, how do those backup programs work, where
> they are able to backup whilst files are active.  How does an airline
> bookings database for example get backed up, where they have to remain
> pretty much running 24/7?  Just out of interest.
>
> Alex
>
> "Robert" <ngsemail2005withoutthis@yahoo.com.ar> wrote in message
> news:ADC69599-4EF5-42AC-A796-58B98D5F6243@news.elevatesoft.com...
>>
>> "Al VAs" <deleteprefix_alex@favour.com.au> wrote in message
>> news:7CC09ECD-D05C-4F6E-A579-5A6E7F100B5A@news.elevatesoft.com...
>>> Hi Roy,
>>>
>>> Thanks for your response.  At the momen it is 3.30 DBISAM.  So just to
>>> confirm, if I exclusively open a table, then I can safely copy that
>>> table?
>>
>> If it is a table that is kept open by the application, you can safely
>> backup the whole database. The fact that you were able to open it
>> exclusively means you are the only user. In fact, you could set up a
>> dummy one record table just for that purpose. Of course, you have to have
>> a way to let a user know that the table is not available, if someone
>> tries to start the application while you are doing the backup.
>>
>>> Also, if I want to do a system-based backup, MUST make sure everyone is
>>> out of the application?
>>>
>>
>> For sure. You are backing up files, not a logical database. You can't
>> allow any updates while you are doing the backup.
>>
>> Robert
>>
>>
>>
>
>

Wow, and that works fine?  So if you performed a DBISAM 4 backup, the first
files backed up in the process are backed up at the the same instant as th
last, as this is the only way you can ensure integrity in data.

Regards

Alex

"Omik_1" <kimowaugh@yahoo.com> wrote in message
news:ADA2CD14-77DF-4583-AC33-F00670CBA7E7@news.elevatesoft.com...
> They may be using DBISAM v4.x .It allows you to backup while using the
> database.
>
>
> "Al VAs" <deleteprefix_alex@favour.com.au> wrote in message
> news:F6257D4F-0203-4FAF-9544-51E5CC44D68A@news.elevatesoft.com...
>> Hi Robert,
>>
>> Thanks.  Just on that last point, how do those backup programs work,
>> where they are able to backup whilst files are active.  How does an
>> airline bookings database for example get backed up, where they have to
>> remain pretty much running 24/7?  Just out of interest.
>>
>> Alex
>>
>> "Robert" <ngsemail2005withoutthis@yahoo.com.ar> wrote in message
>> news:ADC69599-4EF5-42AC-A796-58B98D5F6243@news.elevatesoft.com...
>>>
>>> "Al VAs" <deleteprefix_alex@favour.com.au> wrote in message
>>> news:7CC09ECD-D05C-4F6E-A579-5A6E7F100B5A@news.elevatesoft.com...
>>>> Hi Roy,
>>>>
>>>> Thanks for your response.  At the momen it is 3.30 DBISAM.  So just to
>>>> confirm, if I exclusively open a table, then I can safely copy that
>>>> table?
>>>
>>> If it is a table that is kept open by the application, you can safely
>>> backup the whole database. The fact that you were able to open it
>>> exclusively means you are the only user. In fact, you could set up a
>>> dummy one record table just for that purpose. Of course, you have to
>>> have a way to let a user know that the table is not available, if
>>> someone tries to start the application while you are doing the backup.
>>>
>>>> Also, if I want to do a system-based backup, MUST make sure everyone is
>>>> out of the application?
>>>>
>>>
>>> For sure. You are backing up files, not a logical database. You can't
>>> allow any updates while you are doing the backup.
>>>
>>> Robert
>>>
>>>
>>>
>>
>>
>
>

Hi,

> Wow, and that works fine?
Yes.


>So if you performed a DBISAM 4 backup, the first files backed up in the
>process are backed up at the the same instant as th last, as this is the
>only way you can ensure integrity in data.

No.
The backup runs inside a transaction, so other users can read the database
but can't change it until the backup is completed. It is a fast process, so
if you backup to HD, it will block writes only for short time.


--
Fernando Dias
EasyGate, Lda