Informix

Hello everyone.

We are running 14.10 in SDS mode. Roughly 2 weeks ago a heavy update was performed on the primary which resulted in a lot of 

9/29/2021 13:32:10 Dynamically allocated new virtual shared memory segment (size 134400KB)

on the secondary (48 segments were allocated). The problem is that these segments are all still in use (blkfree=1) so onmode -F won't work. No allocation took place on the primary during this update.
Is this normal?
The primary does allocate new segments from time to time but they can always be freed after the session causing the allocation has finished.
I've had this issue before and then I had to reboot the secondary to get rid of these segments.

Thanks in advance,
-Snorri




------------------------------
Snorri Bergmann
------------------------------

#Informix

onstat -g afr

What is the fragment in each additional shared memory segment?

Which thread does that come from?

Is that ffrom a user session?

Regards,

David.

------------------------------
David Williams
------------------------------

Original Message:
Sent: Fri October 15, 2021 07:21 AM
From: Snorri Bergmann
Subject: Virtual segments on SDS server

Hello everyone.

We are running 14.10 in SDS mode. Roughly 2 weeks ago a heavy update was performed on the primary which resulted in a lot of 

9/29/2021 13:32:10 Dynamically allocated new virtual shared memory segment (size 134400KB)

on the secondary (48 segments were allocated). The problem is that these segments are all still in use (blkfree=1) so onmode -F won't work. No allocation took place on the primary during this update.
Is this normal?
The primary does allocate new segments from time to time but they can always be freed after the session causing the allocation has finished.
I've had this issue before and then I had to reboot the secondary to get rid of these segments.

Thanks in advance,
-Snorri




------------------------------
Snorri Bergmann
------------------------------

#Informix

Thanks David.

I'm not sure how I can determine the thread the segment(s) belong to. But they don't belong to any running session, that's for sure.

Best regards,
-Snorri

------------------------------
Snorri Bergmann
------------------------------

Original Message:
Sent: Sun October 17, 2021 06:10 PM
From: David Williams
Subject: Virtual segments on SDS server

onstat -g afr

What is the fragment in each additional shared memory segment?

Which thread does that come from?

Is that ffrom a user session?

Regards,

David.

------------------------------
David Williams

Original Message:
Sent: Fri October 15, 2021 07:21 AM
From: Snorri Bergmann
Subject: Virtual segments on SDS server

Hello everyone.

We are running 14.10 in SDS mode. Roughly 2 weeks ago a heavy update was performed on the primary which resulted in a lot of 

9/29/2021 13:32:10 Dynamically allocated new virtual shared memory segment (size 134400KB)

on the secondary (48 segments were allocated). The problem is that these segments are all still in use (blkfree=1) so onmode -F won't work. No allocation took place on the primary during this update.
Is this normal?
The primary does allocate new segments from time to time but they can always be freed after the session causing the allocation has finished.
I've had this issue before and then I had to reboot the secondary to get rid of these segments.

Thanks in advance,
-Snorri




------------------------------
Snorri Bergmann
------------------------------

#Informix

On a stand-alone database server, I often encounter the phenomenon that there are many V segments (blkfree = 1), so onmode - F will not work.
Once, segment V was allocated quickly when an application of the developer was started. The final positioning was that there was a problem with the writing of the application.
But more often it is impossible to locate who caused it.

------------------------------
ZhiWei Cui
GBASE
ShiJiaZhuang
------------------------------

Original Message:
Sent: Mon October 18, 2021 11:58 AM
From: Snorri Bergmann
Subject: Virtual segments on SDS server

Thanks David.

I'm not sure how I can determine the thread the segment(s) belong to. But they don't belong to any running session, that's for sure.

Best regards,
-Snorri

------------------------------
Snorri Bergmann

Original Message:
Sent: Sun October 17, 2021 06:10 PM
From: David Williams
Subject: Virtual segments on SDS server

onstat -g afr

What is the fragment in each additional shared memory segment?

Which thread does that come from?

Is that ffrom a user session?

Regards,

David.

------------------------------
David Williams

Original Message:
Sent: Fri October 15, 2021 07:21 AM
From: Snorri Bergmann
Subject: Virtual segments on SDS server

Hello everyone.

We are running 14.10 in SDS mode. Roughly 2 weeks ago a heavy update was performed on the primary which resulted in a lot of 

9/29/2021 13:32:10 Dynamically allocated new virtual shared memory segment (size 134400KB)

on the secondary (48 segments were allocated). The problem is that these segments are all still in use (blkfree=1) so onmode -F won't work. No allocation took place on the primary during this update.
Is this normal?
The primary does allocate new segments from time to time but they can always be freed after the session causing the allocation has finished.
I've had this issue before and then I had to reboot the secondary to get rid of these segments.

Thanks in advance,
-Snorri




------------------------------
Snorri Bergmann
------------------------------

#Informix

Just a thought...If the lock table was dynamically expanded during the big update, they may allocate space in additional virtual memory segments, and thereby prevent you from releasing the segments with onmode -F

If this happened, you will see messages in the Informix log, and onstat -k | tail will show if there were any lock table overflows.




------------------------------
Mike Walker
xDB Systems, Inc
www.xdbsystems.com
------------------------------

Original Message:
Sent: Fri October 15, 2021 07:21 AM
From: Snorri Bergmann
Subject: Virtual segments on SDS server

Hello everyone.

We are running 14.10 in SDS mode. Roughly 2 weeks ago a heavy update was performed on the primary which resulted in a lot of 

9/29/2021 13:32:10 Dynamically allocated new virtual shared memory segment (size 134400KB)

on the secondary (48 segments were allocated). The problem is that these segments are all still in use (blkfree=1) so onmode -F won't work. No allocation took place on the primary during this update.
Is this normal?
The primary does allocate new segments from time to time but they can always be freed after the session causing the allocation has finished.
I've had this issue before and then I had to reboot the secondary to get rid of these segments.

Thanks in advance,
-Snorri




------------------------------
Snorri Bergmann
------------------------------

#Informix