Document fins/I0530-1
FIN #: I0530-1
SYNOPSIS: The Enterprise 10000 may be susceptible to system hangs if ISM is not
enabled.
DATE: Oct/27/99
KEYWORDS: The Enterprise 10000 may be susceptible to system hangs if ISM is not
enabled.
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- Sun Proprietary/Confidential: Internal Use Only -
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FIELD INFORMATION NOTICE
(For Authorized Distribution by SunService)
SYNOPSIS: The Enterprise 10000 may be susceptible to system hangs
if ISM is not enabled.
TOP FIN/FCO REPORT: Yes
PRODUCT_REFERENCE: ISM memory management code bug
PRODUCT CATEGORY: Server / SW Admin;
PRODUCTS AFFECTED:
Mkt_ID Platform Model Description Serial Number
------ -------- ----- ----------- -------------
Systems Affected
----------------
E10000 E10000 ALL Ultra Enterprise E10000 Server -
X-Options Affected
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- - - - -
PART NUMBERS AFFECTED:
Part Number Description Model
----------- ----------- -----
- - -
BugId: 4244523, 4228856
ESC: 519284, 519149, 520540, 521017, 521212, 521850
PatchId: 
105181, 105181 and greater
PROBLEM DESCRIPTION:
E10K systems running Solaris 2.6 can degrade to the point of appearing
hung. This can be caused by Intimate Shared Memory (ISM) being disabled.
Problem summary shown below:
1. A data corruption problem was discovered on E10K systems (only)
running the 105181 patch or less. The problem was tracked to
a bug (BugIDs 4244523 and 4228856) in the ISM memory management
code. The only realistic workaround was to disable ISM.
2. Customers, not wanting to risk data corruption, disabled ISM.
3. The 105181 patch was released, which fixes the ISM problem.
4. Customers install 105181 (or higher), but may have forgotten
re-enable ISM.
5. With ISM disabled, a system will eventually grind itself into what
appears to be in a hung state. This is due to an excessive use of
kernel memory in the sfmmu8_cache caused by ISM not being enabled.
The sfmmu8_cache size can be checked using crash, with the subcommand
of kmastat.
IMPLEMENTATION:
---
| | MANDATORY (Fully Pro-Active)
---
---
| X | CONTROLLED PRO-ACTIVE (per Sun Geo Plan)
---
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| | REACTIVE (As Required)
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CORRECTIVE ACTION:
E10K customers running databases which are capable of using ISM (almost
all databases are capable of this) should ensure that ISM is enabled if
they are running patch 105181 or higher.
How to enable Intimate Shared Memory (ISM):
-------------------------------------------
By default, ISM is available for use when the system boots. But whether
ISM is actually getting used or not is dependent on the application making
the proper request to have its shared memory attached in ISM mode. Changes
need to be made at both the OS and application levels.
On the OS side, this default behavior can be changed with two parameters
in the /etc/system file:
set shmsys:ism_off=1 Force ISM off no matter what
set shmsys:ism_off=0 Default behavior above
set shmsys:share_page_table=1 Force ISM attaches no matter what
set shmsys:share_page_table=0 Default behavior above
By setting ism_off to one, you can forcibly disable ISM attaches no matter
what the application wants to do. By setting share_page_table to one,
you can force all attaches to be in ISM mode no matter what the application
specifies. share_page_table takes precedence over ism_off, so if both
are one, ISM is forced. Both of the above parameters are considered
"internal
use only" and were added for testing purposes; they should never appear in
a
customer's /etc/system file.
On the application side, for example in Oracle, there is a parameter in the
init.ora file (called use_ism) that tells Oracle to always attach shared
memory in ISM mode. Check with the vendor of other RDBMS's to see how they
do it.
Summary: How to Enable ISM:
---------------------------
1. Remove any references to ism_off or share_page_table from the /etc/system
file.
2. Configure the applications to select ISM using the application
configuration files, e.g. init.ora.
COMMENTS:
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Implementation Footnote:
i) In case of MANDATORY FINs, Enterprise Services will attempt to
contact all affected customers to recommend implementation of
the FIN.
ii) For CONTROLLED PROACTIVE FINs, Enterprise Services mission critical
support teams will recommend implementation of the FIN (to their
respective accounts), at the convenience of the customer.
iii) For REACTIVE FINs, Enterprise Services will implement the FIN as the
need arises.
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