Here’s what happened to me 6 years ago on a system I had configured to use linear logging. It could have been a defect for all I know since I never pursued it. I was running the linear log clean-up script and a rcdmqimg script as cron jobs on AIX. The object that had become corrupted was a queue that was not touched over a very long interval. When it was finally accessed and MQ informed me that it was corrupted I attempted a recovery. The recovery image was also corrupted. I had to delete and redefine the object. That experience certainly “tainted” my once “pure” opinion of linear logging. I now tend to think it is a lot of additional effort for something that may or may not work depending on how the planets are aligned and whether or not someone waved some magic feathers in the direction of the shared disk facility. Perhaps a bit of over dramatization, but, it underscores the fact that you should have a “worst case” process in place in case you need it.

Maybe someone in Hursley would care to comment on the scenario I just described.

-----Original Message-----
From: MQSeries List [mailto:MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org] On Behalf Of Potkay, Peter M (ISD, IT)
Sent: Sunday, March 02, 2008 11:15 AM
To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
Subject: Re: Linear logging / media recovery

http://www.ibm.com/developerworks/websphere/library/techarticles/0712_dunn/0712_dunn.html

"If you need to be able to forward recover queue data following a failure or recover from media failure of the device containing the log you must use linear logging if you are dependent on WebSphere MQ to provide this level of protection for you. An alternative strategy is to use disk mirroring to mirror the log device. This is often a facility provided by a SAN. In this case you could use circular logging."

Peter Potkay

From: MQSeries List [mailto:MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org] On Behalf Of Darren Douch
Sent: Sunday, March 02, 2008 11:29 AM
To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
Subject: Re: Linear logging / media recovery

Aye, but was there anything on that damaged object that needed
recovering, or was it an empty queue that could simply have been deleted
/ redefined? In a 'MQ is not a database' world, surely that would be
the case?

Note I am not arguing one way or the other here... just after honest
opinions either way.

Thanks Bobbee.

Darren.


Robert Broderick wrote:
> Damn, I am so glad you just asked this. Timing is everything.
>
> Just was involved in a migration for a customer. Had to come to
> Champaign, Il for the weekend. Aside from all the other stuff they
> upgraded DB2, MQWF, MQ and WMB. In the middle of it the SA running the
> scripts calls over and sez he has gotten an error code. After some
> looking it was a case of damaged object. My next question was what
> logging were they running. He replied Linear, I replied good boy!!!
> Off we were after one or two commands.
>
> This is the third time in my career that I have relied on the fact
> that there were Linear logs in production.
>
> I wonder which side of the fence I sit on with regards to this subject.
>
>
>
>
> ------------------------------------------------------------------------
> Date: Sun, 2 Mar 2008 08:28:14 +0000
> From: douchd-deqWdTs+PzCuvtTkCOosKA@public.gmane.org
> Subject: Linear logging / media recovery
> To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
>
> Presumably lots of people out there use linear logging because
> it's the
> recommended way to operate in 'serious' environments... but how
> widespread is the practice of actually performing media recovery?
> Obviously we are all just using MQ for items in transit - DB2 is
> being
> used for our database requirements ;) so is media recovery really
> needed
> in the real world, or just in theory?
>
> Cheers
> Darren
>
>
> ------------------------------------------------------------------------
> Messenger on the move. Text MSN to 63463 now!
>
> ------------------------------------------------------------------------
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> - Manage
> Your List Settings
> -
> Unsubscribe
>
> Instructions for managing your mailing list subscription are
> provided in the Listserv General Users Guide available at
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>
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> -
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*************************************************************************
This communication, including attachments, is
for the exclusive use of addressee and may contain proprietary,
confidential and/or privileged information. If you are not the intended
recipient, any use, copying, disclosure, dissemination or distribution is
strictly prohibited. If you are not the intended recipient, please notify
the sender immediately by return e-mail, delete this communication and
destroy all copies.
*************************************************************************

Here’s what happened to me 6 years ago on a system I had configured to use linear logging. It could have been a defect for all I know since I never pursued it. I was running the linear log clean-up script and a rcdmqimg script as cron jobs on AIX. The object that had become corrupted was a queue that was not touched over a very long interval. When it was finally accessed and MQ informed me that it was corrupted I attempted a recovery. The recovery image was also corrupted. I had to delete and redefine the object. That experience certainly “tainted” my once “pure” opinion of linear logging. I now tend to think it is a lot of additional effort for something that may or may not work depending on how the planets are aligned and whether or not someone waved some magic feathers in the direction of the shared disk facility. Perhaps a bit of over dramatization, but, it underscores the fact that you should have a “worst case” process in place in case you need it.

Maybe someone in Hursley would care to comment on the scenario I just described.

-----Original Message-----
From: MQSeries List [mailto:MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org] On Behalf Of Potkay, Peter M (ISD, IT)
Sent: Sunday, March 02, 2008 11:15 AM
To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
Subject: Re: Linear logging / media recovery

http://www.ibm.com/developerworks/websphere/library/techarticles/0712_dunn/0712_dunn.html

"If you need to be able to forward recover queue data following a failure or recover from media failure of the device containing the log you must use linear logging if you are dependent on WebSphere MQ to provide this level of protection for you. An alternative strategy is to use disk mirroring to mirror the log device. This is often a facility provided by a SAN. In this case you could use circular logging."

Peter Potkay

From: MQSeries List [mailto:MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org] On Behalf Of Darren Douch
Sent: Sunday, March 02, 2008 11:29 AM
To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
Subject: Re: Linear logging / media recovery

Aye, but was there anything on that damaged object that needed
recovering, or was it an empty queue that could simply have been deleted
/ redefined? In a 'MQ is not a database' world, surely that would be
the case?

Note I am not arguing one way or the other here... just after honest
opinions either way.

Thanks Bobbee.

Darren.


Robert Broderick wrote:
> Damn, I am so glad you just asked this. Timing is everything.
>
> Just was involved in a migration for a customer. Had to come to
> Champaign, Il for the weekend. Aside from all the other stuff they
> upgraded DB2, MQWF, MQ and WMB. In the middle of it the SA running the
> scripts calls over and sez he has gotten an error code. After some
> looking it was a case of damaged object. My next question was what
> logging were they running. He replied Linear, I replied good boy!!!
> Off we were after one or two commands.
>
> This is the third time in my career that I have relied on the fact
> that there were Linear logs in production.
>
> I wonder which side of the fence I sit on with regards to this subject.
>
>
>
>
> ------------------------------------------------------------------------
> Date: Sun, 2 Mar 2008 08:28:14 +0000
> From: douchd-deqWdTs+PzCuvtTkCOosKA@public.gmane.org
> Subject: Linear logging / media recovery
> To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
>
> Presumably lots of people out there use linear logging because
> it's the
> recommended way to operate in 'serious' environments... but how
> widespread is the practice of actually performing media recovery?
> Obviously we are all just using MQ for items in transit - DB2 is
> being
> used for our database requirements ;) so is media recovery really
> needed
> in the real world, or just in theory?
>
> Cheers
> Darren
>
>
> ------------------------------------------------------------------------
> Messenger on the move. Text MSN to 63463 now!
>
> ------------------------------------------------------------------------
> List Archive
> - Manage
> Your List Settings
> -
> Unsubscribe
>
> Instructions for managing your mailing list subscription are
> provided in the Listserv General Users Guide available at
> http://www.lsoft.com
>
>
> ------------------------------------------------------------------------
> Connect and share in new ways with Windows Live. Get it now!
>
> ------------------------------------------------------------------------
> List Archive
> - Manage Your List Settings
> -
> Unsubscribe
>
>
>
> Instructions for managing your mailing list subscription are provided
> in the Listserv General Users Guide available at http://www.lsoft.com
>
>

She said what? About who? Shameful celebrity quotes on Search Star!

List Archive - Manage Your List Settings - Unsubscribe

Instructions for managing your mailing list subscription are provided in the Listserv General Users Guide available at http://www.lsoft.com

*************************************************************************
This communication, including attachments, is
for the exclusive use of addressee and may contain proprietary,
confidential and/or privileged information. If you are not the intended
recipient, any use, copying, disclosure, dissemination or distribution is
strictly prohibited. If you are not the intended recipient, please notify
the sender immediately by return e-mail, delete this communication and
destroy all copies.
*************************************************************************

Here’s what happened to me 6 years ago on a system I had configured to use linear logging. It could have been a defect for all I know since I never pursued it. I was running the linear log clean-up script and a rcdmqimg script as cron jobs on AIX. The object that had become corrupted was a queue that was not touched over a very long interval. When it was finally accessed and MQ informed me that it was corrupted I attempted a recovery. The recovery image was also corrupted. I had to delete and redefine the object. That experience certainly “tainted” my once “pure” opinion of linear logging. I now tend to think it is a lot of additional effort for something that may or may not work depending on how the planets are aligned and whether or not someone waved some magic feathers in the direction of the shared disk facility. Perhaps a bit of over dramatization, but, it underscores the fact that you should have a “worst case” process in place in case you need it.

Maybe someone in Hursley would care to comment on the scenario I just described.

-----Original Message-----
From: MQSeries List [mailto:MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org] On Behalf Of Potkay, Peter M (ISD, IT)
Sent: Sunday, March 02, 2008 11:15 AM
To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
Subject: Re: Linear logging / media recovery

http://www.ibm.com/developerworks/websphere/library/techarticles/0712_dunn/0712_dunn.html

"If you need to be able to forward recover queue data following a failure or recover from media failure of the device containing the log you must use linear logging if you are dependent on WebSphere MQ to provide this level of protection for you. An alternative strategy is to use disk mirroring to mirror the log device. This is often a facility provided by a SAN. In this case you could use circular logging."

Peter Potkay

From: MQSeries List [mailto:MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org] On Behalf Of Darren Douch
Sent: Sunday, March 02, 2008 11:29 AM
To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
Subject: Re: Linear logging / media recovery

Aye, but was there anything on that damaged object that needed
recovering, or was it an empty queue that could simply have been deleted
/ redefined? In a 'MQ is not a database' world, surely that would be
the case?

Note I am not arguing one way or the other here... just after honest
opinions either way.

Thanks Bobbee.

Darren.


Robert Broderick wrote:
> Damn, I am so glad you just asked this. Timing is everything.
>
> Just was involved in a migration for a customer. Had to come to
> Champaign, Il for the weekend. Aside from all the other stuff they
> upgraded DB2, MQWF, MQ and WMB. In the middle of it the SA running the
> scripts calls over and sez he has gotten an error code. After some
> looking it was a case of damaged object. My next question was what
> logging were they running. He replied Linear, I replied good boy!!!
> Off we were after one or two commands.
>
> This is the third time in my career that I have relied on the fact
> that there were Linear logs in production.
>
> I wonder which side of the fence I sit on with regards to this subject.
>
>
>
>
> ------------------------------------------------------------------------
> Date: Sun, 2 Mar 2008 08:28:14 +0000
> From: douchd-deqWdTs+PzCuvtTkCOosKA@public.gmane.org
> Subject: Linear logging / media recovery
> To: MQSERIES-0lvw86wZMd9k/bWDasg6f+2wyY2g16FtwPuJ0ROkVbw@public.gmane.org
>
> Presumably lots of people out there use linear logging because
> it's the
> recommended way to operate in 'serious' environments... but how
> widespread is the practice of actually performing media recovery?
> Obviously we are all just using MQ for items in transit - DB2 is
> being
> used for our database requirements ;) so is media recovery really
> needed
> in the real world, or just in theory?
>
> Cheers
> Darren
>
>
> ------------------------------------------------------------------------
> Messenger on the move. Text MSN to 63463 now!
>
> ------------------------------------------------------------------------
> List Archive
> - Manage
> Your List Settings
> -
> Unsubscribe
>
> Instructions for managing your mailing list subscription are
> provided in the Listserv General Users Guide available at
> http://www.lsoft.com
>
>
> ------------------------------------------------------------------------
> Connect and share in new ways with Windows Live. Get it now!
>
> ------------------------------------------------------------------------
> List Archive
> - Manage Your List Settings
> -
> Unsubscribe
>
>
>
> Instructions for managing your mailing list subscription are provided
> in the Listserv General Users Guide available at http://www.lsoft.com
>
>

She said what? About who? Shameful celebrity quotes on Search Star!

List Archive - Manage Your List Settings - Unsubscribe

Instructions for managing your mailing list subscription are provided in the Listserv General Users Guide available at http://www.lsoft.com

*************************************************************************
This communication, including attachments, is
for the exclusive use of addressee and may contain proprietary,
confidential and/or privileged information. If you are not the intended
recipient, any use, copying, disclosure, dissemination or distribution is
strictly prohibited. If you are not the intended recipient, please notify
the sender immediately by return e-mail, delete this communication and
destroy all copies.
*************************************************************************