PI71866: DUPLICATE HA RECORDS CAUSE STANDBY ULB HANG

Fixes are available

APAR status

Closed as program error.

Error description

Standby ULB hang due to incorrect locking when duplicate HA
records are received by the standby LB.

Local fix

Problem summary

****************************************************************
* USERS AFFECTED:  IBM WebSphere Application Server Edge Load  *
*                  Balancer for ipv4 and ipv6 users            *
****************************************************************
* PROBLEM DESCRIPTION: Various problems exist when using the   *
*                      high availability function.             *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
When using the high availability function, various problems
occur.
-- The backup load balancer tried to check the validity of
replication records with the current state information it had
about the connection and this would cause problems because the
backup is not guaranteed to receive every update. The
connection table could get corrupted due to this and could
lead to a crash or messages logged about invalid states or
list errors messages.
-- The backup LB would use excessive memory and CPU because it
does not maintain the connection records in order of their
last access and the garbage collection code depended upon this
ordering.
On AIX, hangs could occur as well as traps.

Problem conclusion

Code was corrected to remove state checking on the backup LB;
the primary LB replication updates are trusted and validation
is not required. The garbage collection algorithm was modified
to check the entire table but to run less often than the
primary to eliminate the excessive memory and cpu usage.

On AIX, garbage collection was moved to run under a lower
priority thread to prevent problems with system interrupts
from incoming data. This change affected AIX only because AIX
has code which runs in the OS kernel; other operating systems
supported by ULB do not function in this manner.

Fix levels:
    8.0.0.13
    8.5.5.12
    9.0.0.3

Temporary fix

Comments

APAR Information

APAR number
PI71866
Reported component name
WS EDGE LB IPV4
Reported component ID
5724H8812
Reported release
850
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2016-11-07
Closed date
2016-12-06
Last modified date
2016-12-06

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name
WS EDGE LB IPV4
Fixed component ID
5724H8812

Applicable component levels

R800 PSY
UP
R850 PSY
UP
R900 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.5","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
04 May 2022

Tips

PI71866: DUPLICATE HA RECORDS CAUSE STANDBY ULB HANG

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

R800 PSY

R850 PSY

R900 PSY

Document Information

Share your feedback

Need support?