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Thread Database replication and DB corruption
Mon, Jan 30 2006 3:00 PMPermanent Link

"Halim Boumedjirek"
Do you think that folder replication tools can cause a database corruption
if the DB is under massive insert/update requests?
We are using BrightStor from Computer associates. I would like to know if
you guys are familiar with it and if you recommend having this kind of DB
replication without using DB calls. Basicaly, we have a live DB replication
from server1 to server2 through the LAN. The database is over 2 GB and can
get over 20 transactions / second.
We are using Windows 2003 Server.
thank you,
-Halim

Tue, Jan 31 2006 7:41 AMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Halim,

<< Do you think that folder replication tools can cause a database
corruption if the DB is under massive insert/update requests?We are using
BrightStor from Computer associates. I would like to know if you guys are
familiar with it and if you recommend having this kind of DB replication
without using DB calls. Basicaly, we have a live DB replication from server1
to server2 through the LAN. The database is over 2 GB and can get over 20
transactions / second. >>

My recommendation would be to disable it and see if things improve.  It
shouldn't cause corruption, but it most certainly could cause
performance/locking issues if the activity is heavy enough.  It may/should
be smart enough to only replicate the changed portions of a file, but if it
isn't then you'll have a really big issue with performance.

--
Tim Young
Elevate Software
www.elevatesoft.com

Tue, Jan 31 2006 8:05 AMPermanent Link

"Halim Boumedjirek"
We are going to test our system with and without the replication process and
see compare the results.
Thank you,
-Halim
"Tim Young [Elevate Software]" <timyoung@elevatesoft.com> wrote in message
news:AE32887B-390F-4C23-B9F3-63DE023AD48E@news.elevatesoft.com...
> Halim,
>
> << Do you think that folder replication tools can cause a database
> corruption if the DB is under massive insert/update requests?We are using
> BrightStor from Computer associates. I would like to know if you guys are
> familiar with it and if you recommend having this kind of DB replication
> without using DB calls. Basicaly, we have a live DB replication from
> server1 to server2 through the LAN. The database is over 2 GB and can get
> over 20 transactions / second. >>
>
> My recommendation would be to disable it and see if things improve.  It
> shouldn't cause corruption, but it most certainly could cause
> performance/locking issues if the activity is heavy enough.  It may/should
> be smart enough to only replicate the changed portions of a file, but if
> it isn't then you'll have a really big issue with performance.
>
> --
> Tim Young
> Elevate Software
> www.elevatesoft.com
>
>

Tue, Jan 31 2006 7:07 PMPermanent Link

Eryk Bottomley
Tim

> My recommendation would be to disable it and see if things improve.  It
> shouldn't cause corruption,

It shouldn't corrupt the DB it is reading but the DB it is writing
should certainly be corrupt (on a regular basis) - either that or the
product won't function at all. Assuming it is actually (appearing to)
work then it must be doing dirty reads of the table files asynchronously
with DBISAM writes - ergo the IDXs and BLBs are bound to get out of
whack sooner or later?

Eryk
Wed, Feb 1 2006 8:08 AMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

Avatar

Email timyoung@elevatesoft.com

Eryk,

<< Assuming it is actually (appearing to) work then it must be doing dirty
reads of the table files asynchronously with DBISAM writes - ergo the IDXs
and BLBs are bound to get out of whack sooner or later? >>

It depends.  If it is using the I/O sub-system hooks in Windows, then it
might be intercepting the API calls and redirecting them to the hot backups
in real time.  On the other hand, if it isn't, then all of the above
applies. Smiley

--
Tim Young
Elevate Software
www.elevatesoft.com

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