Before migrating to AIX 6.1 you might want to check that ncargs is set to a value greater than or equal to 256 e.g.
# chdev -l sys0 -a ncargs=256
$ lsattr -El sys0 -a ncargs
ncargs 256 ARG/ENV list size in 4K byte blocks True
Let me elaborate.
fullcore -
Was set to true before migration. Set to false after migration.
iostat -
Was set to true before migration. Set to false after migration.
maxuproc -
Was set to 2048 before migration. Set to 128 after migration.
---------------------
After building more debug methods and performing
further debug, which
involves multiple restore attempts, we figured out
the root cause.
- During second phase of boot, when cfgsys_chrp
run, it tries to set all
customized values for sys0 device. However, in this process, if and
when an error occurs, all customized values for
sys0 will be reset to
allow the system to boot. (Instead of hang/crash).
- In the case of the customer's scenario, when
cfgsys_chrp() tries to set ncargs
to value of 30, it fails with an error. Reason being, for
AIX 6.1, minimum value for ncargs is 256. If it is
less than 256, the kernel
returns an error and then cfgsys_chrp
"resets" all customized attribute
values for sys0 to their defaults.
---------------------
IN SETVAR()
Error changing v_ncargs,rc=-1
Error during SYS_SETPARMS, errno=22
Invalid value in SYS_SETPARMS
---------------------
# odmget -q "attribute=ncargs" PdAt
PdAt:
uniquetype =
"sys/node/chrp"
attribute = "ncargs"
deflt =
"256"
values =
"256-1024,1"
width =
""
type =
"R"
generic =
"DU"
rep =
"nr"
nls_index = 71
---------------------
ncargs
Purpose: Specifies the maximum allowable size of
the ARG/ENV list (in 4
KB blocks) when running exec() subroutines.
Values: Default: 256; Range: 256 to 1024
Display: lsattr -E -l sys0 -a ncargs
Change: chdev -l sys0 -a ncargs= NewValue Change
takes effect
immediately and is preserved over boot.
Diagnosis: Users cannot execute any additional
processes because the
argument list passed to the exec() system call is
too long. A low
default value might cause some programs to fail
with the arg list too
long error message, in which case you might try
increasing the ncargs
value with the chdev command above and then
rerunning the program.
Tuning: This is a mechanism to prevent the exec()
subroutines from
failing if the argument list is too long. Please
note that tuning to a
higher ncargs value puts additional constraints on
system memory
resources.
---------------------
As per discussion with Architect, this is not an
issue with cfgsys_chrp.
However, when the limit for ncargs was changed, it
should have changed
appropriately to handle migration cases. I need to follow up with the
team that handles this for a solution.
As per work around, before migration, make sure ncargs
is
greater than or equal to 256.
Action Plan :
- More updates to follow about the solution after
discussion with team
that handles ncargs.
---------------------
If anyone is interested, I’ll update my blog again, as soon as a fix is available. In the
meantime check the ncargs
value before you start a migration to AIX 6.1, just in case.
Comments (7)
Hi Chris, <div> </div> Good morning. We just experienced the same issue today, wherein the maxuproc has changed from 16384 to 2048 after the aix6.1 upgrade. <div> </div> Has IBM able to find out the root cause? Thanks in advance. <div> </div> Regards, <div> </div> FB
Take a look at the following APARs: <div> </div> AIX 6.1: <br /> IZ87406: MIGRATION DOES NOT PRESERVE MOST OF THE SYS0 ATTRIBUTES <br /> https://www-304.ibm.com/support/docview.wss?uid=isg1IZ74150 <div> </div> AIX 7.1: <br /> IZ87406: MIGRATION DOES NOT PRESERVE MOST OF THE SYS0 ATTRIBUTES <br /> https://www-304.ibm.com/support/docview.wss?uid=isg1IZ87406 <div> </div> Seems that the problem persists even now?
Just for reference... we just experienced the same problem migrating from 5.3 TL12-SP4 to AIX 6.1 TL6 SP6, so the problem still persists. MAXUPROC reset to default. <br />
Hi Marcelo, thanks for sharing. It's good to know the problem still exists, but it's also disappointing that the problem has not been resolved. <div> </div> Did you log a call with IBM? Did they give you a PMR number for the problem? Did they mention any specific APARs for the issue? <div> </div> Cheers. <div> </div> Chris
Hi Chris, <div> </div> We are also having issue with AIX migration to 6.1 from 5.3. We have issue that kbiod process using high CPU. <div> </div> # lsattr -El sys0 <br /> SW_dist_intr false Enable SW distribution of interrupts True <br /> autorestart true Automatically REBOOT OS after a crash True <br /> boottype disk N/A False <br /> capacity_inc 1.00 Processor capacity increment False <br /> capped true Partition is capped False <br /> chown_restrict true Chown Restriction Mode True <br /> conslogin enable System Console Login False <br /> cpuguard enable CPU Guard True <br /> dedicated true Partition is dedicated False <br /> enhanced_RBAC true Enhanced RBAC Mode True <br /> ent_capacity 2.00 Entitled processor capacity False <br /> frequency 484000000 System Bus Frequency False <br /> fullcore false Enable full CORE dump True <br /> fwversion IBM,RG060917_d79e18_r Firmware version and revision levels False <br /> ghostdev 0 Recreate devices in ODM on system change True <br /> id_to_partition 0X036E83741EC6DB01 Partition ID False <br /> id_to_system 0X036E83741EC6DB01 System ID False <br /> iostat true Continuously maintain DISK I/O history True <br /> keylock normal State of system keylock at boot time False <br /> log_pg_dealloc true Log predictive memory page deallocation events True <br /> max_capacity 2.00 Maximum potential processor capacity False <br /> max_logname 9 Maximum login name length at boot time True <br /> maxbuf 20 Maximum number of pages in block I/O BUFFER CACHE True <br /> maxmbuf 0 Maximum Kbytes of real memory allowed for MBUFS True <br /> maxpout 8193 HIGH water mark for pending write I/Os per file True <br /> maxuproc 16384 Maximum number of PROCESSES allowed per user True <br /> min_capacity 1.00 Minimum potential processor capacity False <br /> minpout 4096 LOW water mark for pending write I/Os per file True <br /> modelname IBM,7028-6C4 Machine name False <br /> ncargs 256 ARG/ENV list size in 4K byte blocks True <br /> nfs4_acl_compat secure NFS4 ACL Compatibility Mode True <br /> os_uuid 0fb5f73e-07fd-4d5d-88d5-72f47ab23840 N/A True <br /> pre430core false Use pre-430 style CORE dump True <br /> pre520tune disable Pre-520 tuning compatibility mode True <br /> realmem 6291456 Amount of usable physical memory in Kbytes False <br /> rtasversion 1 Open Firmware RTAS version False <br /> sed_config select Stack Execution Disable (SED) Mode True <br /> systemid IBM,0165178BF Hardware system identifier False <br /> variable_weight 0 Variable processor capacity weight False <br />
pls find this output from topas. <div> </div> Name PID CPU% PgSp Owner <br /> kbiod 5308606 96.5 1.1 root
Hi SAPBASIS, <div> </div> Please review the following IBM technote: <div> </div> Kbiod using high CPU: <br /> http://www-01.ibm.com/support/docview.wss?uid=isg3T1012846 <div> </div> I'm not sure it is related to your problem but it is worth a look.